Not that long ago, Barry Marshall was an obscure physician studying the etiology of ulcers at a hospital in Perth, Australia — several thousand literal and figurative miles from the center of the medical universe. His work was unconventional, not to say heretical, and in 1986, he was invited to discuss it at a gastroenterology conference in the United States. His wife came along and, while doing some sightseeing, overheard a conversation among some other gastroenterologists' wives who happened to be sitting in front of her on a bus. "They were talking about this terrible person that they imported from Australia to speak," Marshall told me. "You know: 'How could they put such rubbish in the conference?' "

In 2005, that "terrible person" won the Nobel Prize in medicine . Marshall, along with his colleague and fellow Nobel winner Robin Warren, proved that up to 90 percent of peptic ulcers are caused by a bacterium called Helicobacter pylori — not by stress, as medical wisdom had long held. In most of the interviews in this series, I've talked to people about being wrong: about what they've learned from their own mistakes, and about how their work — whether as an astronaut or speculator or lawyer or marriage counselor — affects how they think about error. But in this interview, Marshall and I talk about being right. In particular, we discuss how it feels when everyone thinks you're wrong, what it takes to get the scientific establishment to change its mind, and what it's like to finally be proven right. All that, plus a guest appearance by Adrienne Marshall, Barry's wife, who describes how she felt when Barry decided to test his ulcer theory by drinking a batch of bacteria.

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Can you describe the received medical wisdom about ulcers before your research?

Peptic ulcers became more common in the 20th century, at the same time that these theories of Freud and other psychoanalysts became popular. And somehow those meshed, and this tradition emerged that ulcers were caused by stress or turmoil in one's life. I don't know where the data came from, but there was this idea that stress caused high acid levels; maybe there was a small amount of evidence for that, although I haven't been able to find it when I've looked. Anyway, all those things added up to convince people that ulcers were caused by stress. There was no proper data of any kind. It was smoke and mirrors as much as anything else, but terribly convincing for everybody.

Are you saying that there was no basically no empirical evidence to support the stress-and-acid hypothesis?

You can always find stress in someone's life if you want to. You ask a few questions and eventually it's, "Yes, I admit, I was worried about something recently." So they tried to find evidence for stress causing ulcers, and whenever they had an experiment which worked, it would just be blown out of all proportion, and everyone would get so much publicity out of it that you would think, "Ah, at last, it's proven." But the data was very bad. And in fact there was plenty of evidence showing that stress didn't make much difference.

What kind of medical advice was dispensed to all these patients with ostensible stress-induced ulcers? "Relax"?

Basically, yes. The medical advice was take antacids and modify your life style. The first drug that came out in the '70s was Tagamet, an acid blocker. By the time Robin Warren and I came along with this idea about bacteria, that was selling $3 billion of medication per year; it was the world's number one drug. And then that type of medication was the number one drug for about 10 years after that, with global sales of $8 billion or something. But it didn't work very well. It was quite sad, really; people were so disappointed, because as soon as they stopped taking their drugs, the ulcers came back.  

What was it about you that made you more immune to all this received wisdom about ulcers?

I guess all my life I've made my own decisions. My mother was a nurse, and in her era, most diseases weren't understood; people put mustard plasters on knees and rubbed camphor on your chest if you had a cough and did funny things to you if you had tuberculosis — all these things that really made very little difference once proper treatments were brought in. She used to be annoyed with me because I would challenge everything she said and not believe anything unless someone could show me the facts. For some reason, that's just the way I was.

Is that what got you interested in ulcers — the apparent lack of facts?

Something like that. The thing that initially excited me was: "Ah-ha! A falsehood!" Robin and I had been looking into these bacteria, and we found that they can survive in stomach acid. You probably don't think that's particularly weird, because you know that there are bacteria that live in Old Faithful and hot springs and so forth. But it really wasn't well-known in the early '80s that there were bacteria that could survive in all these harsh environments. So it started out as: Let's just prove that these bacteria live in the stomach and try to find out how they do that.

That led to ulcers via the side door, if you like, because we were trying to find out who had the bacteria — and lo and behold, we noticed that everybody with ulcers had them. So we said, "Hang on a minute, scientists have been trying to find the cause of ulcers for 50 years. Have they checked out the possibility that it could be an infection?" The answer was, "No, because it's impossible for bacteria to live in the stomach. We wouldn't even consider that."

At what point did you start to suspect that your own theory was right?

We pretty well knew that we had discovered the cause of ulcers within two years of starting the work. One reason was that I was starting to treat a few people with antibiotics, and nine out of 11 seemed to be cured. At the time, the cure rate for ulcers with any other treatment would have been one out of 11. So even though that work was anecdotal and not blinded and not publishable, it was very convincing.

I assume another reason you were so certain is that — rather famously — you swallowed a bunch of Helicobacter bacteria to prove that it caused stomach problems. Not to be blunt, but: What were you thinking? Was that just a way of bypassing the human studies review board process? Were you so convinced that you were right and just impatient to prove it?

It was a decision point. I had to find out if the bacteria could really affect a healthy person and cause gastritis. I'd been working very hard in the previous 12 months on piglets, but I have to tell you that piglets aren't piglets for very long. They just about grow before your eyes, so after six months I had nearly full-sized pigs in our offices and I was wrestling with them and it was chaos. And you can't infect pigs very easily, it turns out, so that failed rather miserably. And the skeptics were so determinedly skeptical that I felt like: I'm never going to prove to these guys that the bacteria are harmful. By then everybody knew that 40 percent of the population had the bacteria and did not have ulcers, so that was making life difficult for me. So I took some bacteria off a patient and cooked it up.

If nothing had happened, it really would have been a spanner in the works for the whole theory. I thought, "If it doesn't work, I'll quiet down about the whole thing; maybe I'll just run away and do some other career for a while because I'm wrong." But then of course it worked.

What did your colleagues think?

I didn't quite explain to my boss what I was doing. He was passing the endoscope on me and I was lying there gagging away, he says, "Barry, I'm not sure why you asked me to do this test on you, and I don't want you to tell me." It was don't ask, don't tell. I wrote the experiment up in the third person, because it was very disreputable to be doing a self-experiment of one and then writing it up, and the editor of the medical journal of Australia stuck his neck out and published it. Afterward a couple of people figured out that it was really a self-experiment on me, but I didn't own up to it straight away.

You didn't realize it was going to be a great PR stunt?

No, I didn't. I was always very embarrassed talking about it. Then the word leaked out, and it's kind of a funny story, actually. After our Lancet paper was published in 1984, Robin and I went out to dinner with our wives, and we were having a few drinks and I let slip that I'd done the experiment. So then he goes home and in the middle of the night, he gets a phone call from a journalist in the United States who'd gotten the time difference wrong. The journalists said, "I'm from Star ," and Robin thought it was like Time magazine or something, and he gave this very in-depth interview about these bacteria that might cause ulcers. At the end the journalist said, "How can you be so sure these bacteria are really harmful?" and Robin says, "Well, Dr. Marshall drank them, and he got so sick he half killed himself!" That was the alcohol talking.

So they write this article in Star that's like "Australian Researcher Experiments on Guinea Pig Lab Assistant!"

I have to ask: How did your wife feel about this little stunt?

[Hollering into the distance] Adrienne, come up here! [To me] I'm not allowed to tell other people what she thinks.

That seems like a good policy.

Adrian [laughing]: I was a bit worried about him. He was very sick, and he didn't talk to me about it ahead of time or I would have probably suggested strongly that he not go ahead with it. But I was more surprised by the reaction of his colleagues when it came out that it was actually a self-experiment. He already had a reputation for being a bit rash and a bit of a hothead, and I fully expected his colleagues to write him off as a complete lunatic. But it was the exact opposite. They all thought it was a wonderful thing to do, which surprised us both, I think. He got a lot of credibility for it, which I wouldn't have expected.

By the time of that self-experiment, Barry, you were reasonably sure that you were right, and you'd been saying so in public for quite some time. Can you describe the general response you received when you first began to publicize your work?

When you start off with a new idea like this, all your scientific pals set out to prove you wrong. That's the scientific process. In my case, people were especially interested in showing that I was wrong, because at the time I was not at the pinnacle of gastroenterology, or even in the mainstream. I didn't know all of its secret teachings, if you like. I would just charge in with this stuff about bacteria, and nobody wanted to be told that they had spent their life doing research on something that somebody in western Australia figured out in 12 months. You can imagine that would be a bit difficult to stomach.

That makes it sound like the driving force was ego and insider/outsider status as much as it was the scientific process.

Well, and money. I think there was a strategy in the pharmaceutical industry to keep the new bacteria theory of ulcers under wraps. At the time we made the discovery, a new antacid was coming out every year or two that was stronger or better in some way, and as each drug was rolled out, the pharmaceutical companies funded scientists to do clinical studies on people with ulcers.  

If these had been truly scientific people who were genuinely interested in discovery, as soon as they heard about the new bacteria [theory], they would've said to the investigator, "We're testing 300 patients with ulcers; can you just take an extra biopsy and check for bacteria? We want to know what's going on here." But they didn't do that, because the only purpose of these trials was to get a new indication and extended registration for the FDA. If you look at it from a business point of view, it could only do your market harm and lower your share price to find out that you could actually cure people with antibiotics. And that was their point of view.

Let me play devil's advocate for a moment. It's easy to characterize your story as the triumph of an evidence-driven outsider over a bunch of insiders and their vested interests, but isn't what happened actually a pretty good example of how science is supposed to work? As you said a moment ago, the scientific process involves trying to prove other people wrong, and in that sense, the fact that you were subjected to a lot of intense questioning and skepticism and so forth seems appropriate.

Right, sure, that's part of it. In retrospect, I was partly to blame, because I would get data that was rather preliminary and try to publish it because it was exciting and novel and original, even though we didn't yet have any kind of double-blind studies.

But also, we felt it was important to act. Maybe it would have been different if we'd been talking about [a cure for] a skin rash or something; maybe you can afford to wait five years until that's proved. But people died from ulcers all over the place and were having their stomachs or half their stomachs removed; there were permanent, mutilating operations and deaths going on around us. And yet to test our idea, you just needed to take some antibiotics. So we weren't very ashamed about trying to get our message out, even though it was rather preliminary.

Thomas Kuhn distinguishes between what he calls normal and extraordinary science, the latter being the type that brings about a complete change — the famed "paradigm shift" — in a field. Which one do you think describes your work? One can arrive at new ideas and theories and solutions without ushering in a whole new paradigm, after all.

It was definitely a paradigm shift, because it got this stress thing debunked. And the implications of that are much bigger: What else is supposedly caused by stress that we can debunk? A lot of these things that are supposedly caused by stress, you try to track down the reason for that link, and there isn't one, except the fact that we don't have any better cause. Everything that's supposedly caused by stress, I tell people there's a Nobel Prize there if you find out the real cause.

So that's one thing that happened. The second thing is that by 1980, everyone was feeling pretty confident that infectious diseases were going to be wiped out and there wasn't going to be any more problem with them. H1N1 is enough to wake us up to the fact that we don't know everything about infectious disease, but it really happened with Helicobacter first. People had been seriously studying ulcers for 50 years, billions of dollars were spent, and then — what do you know, it's a bacteria. So you have to ask, what other infectious diseases are we missing? I reckon a lot of these mysterious chronic diseases are related to some infectious agent that's been a trigger. It might have happened when you were a child and now it [the infectious agent] is long gone, but it sets you up for a problem later in life. We'll see if I'm right.

Speaking of which, did you find it frustrating that so many people felt you were wrong?

It didn't really faze me too much that everybody thought I was wrong, but it annoyed me that I was having trouble getting research grants and so forth. And at times I'd get internally angry, especially when I was junior and people in senior roles and positions of power could block my plans and go ahead and order for someone to have surgery or continue on with some treatment which was useless.

But it must have been annoying for them, too, because you couldn't tell me anything. I just knew so much. After a couple of years, Robin Warren and I knew more about every aspect of ulcers than practically everyone in the world, because we read nothing else for two years.

When and how did you start to convince people?

Part of it had to do with David Graham, who was chief of medicine at Baylor, in Texas, and a thought leader in gastroenterology. Graham started off as a real skeptic but quickly turned around. To his credit, Graham never said that I was wrong. He said, "I don't know, and I'm going to find out." And a couple of years later, he said, "I've checked it out and it looks pretty good, it looks like it could be true."

And then in 1993 or '94, the NIH had a consensus conference, and Tachi Yamada summed it up. Yamada is currently the head of [the Global Health Program of] the Gates Foundation; he's a very, very smart guy, and he said, "Looks like it's proven: Bacteria cause ulcers, and everybody needs to start treating ulcers with antibiotics."

It was just like night and day after that. The whole thing just went ballistic.

How did it feel to finally be acknowledged as right in such a public and universal way?

It was very satisfying to prove [my critics] wrong. People used to say to me afterward, "Barry, do you feel vindicated?" And I'd say, "I felt vindicated 10 years ago, because I knew what the result was going to be." There's a saying, "Science is not a democracy." It doesn't matter how many millions of people there are on the other side. There's one right, and it's perfectly possible for all the rest to be wrong. And ultimately all those guys were proved wrong, and they either retired or they came over the side of Helicobacter .

I love that it took retirement. It's like that quip by the physicist Max Planck, who said that science proceeds by funerals.

It wasn't quite death, but close. David Graham said, "The great thing about Marshall's theory is that if he's wrong, it's going to be so easy to disprove." The point he was making was that if it's a good hypothesis, you can test it. And ours was very testable; you just had to give people antibiotics and see if they got better. And they did. So everybody who was trying to prove us wrong, if they were good scientists, they just changed sides.

If they weren't good scientists, they kind of clammed up and kept doing what they were doing. If they were running a stress-based business — and there were certainly people, particularly in New York, who did psychoanalysis for ulcer patients and ran stress institutes and things like that — a lot of these guys, it had been their whole life. I do feel sorry for them, but I'm glad it wasn't me, that's all I can say. I'd probably be having a lot of trouble with my ego if I'd found out that all my life's work was for naught.

These days, do you find that everyone believes your theory?

Well, not patients, necessarily. Even now I see people who've got ulcers, and they think they're caused by stress. And I say, "Where have you been for the last 20 years? Have you been under a rock?" It just amazes me that there are still doctors out there that don't know this.

Who's to blame for that? Are health care providers and public health workers failing to spread the word, or is the idea just so entrenched in the culture that it's difficult to eradicate?

It's like a religion or something. It's like there's a certain part of your life when you learn things, and then you just stop. I'll say to patients, "Don't you know that ulcers are caused by bacteria? You need some antibiotics." And they'll say to me, "No, no, no. My doctor told me that in my case, it's definitely stress."

Let me turn the tables for a moment. What have you yourself been most wrong about?

It was very difficult to convince me that Helicobacter doesn't always make people unwell. Because I was interested in ulcers, I was seeing people who were very sick from it, but my colleagues would say, "You know, Barry, 40 percent of the Australian population have Helicobacter , and most of those people don't really have any symptoms." And I'd say, "Well, you didn't really ask them the right questions, you've got to ask them this and that." I spent several years trying to separate out people with Helicobacter from people who don't have it on the basis of things like, do they feel nauseated, are they burping, do they have bad breath or headaches — all those kind of vague systems.

I've had to pull back on this. Now I say, "Probably 75 percent of people with Helicobacter have nothing wrong with them." They go through life with minimal syndromes. It's like having dandruff in your stomach. If you had that, you wouldn't ever know about it. Your stomach would look a bit weird if you looked inside, but you wouldn't feel anything at all.

That being said, I'm still trying to hold my ground on this. There's a history of ulcers in my mom's family, and although she swears she has no stomach symptoms at all, I said, "I better just treat you the same way as everybody else." So I gave her antibiotics. Three weeks later she said to me, "You know, since I took those antibiotics, I've just been feeling great. I have more energy, I feel more positive." I've heard that from a lot of people over the years. So I think there may be a subtle syndrome where you're not at your top performance if you have Helicobacter in your stomach. If you've had something mild all your life, then you don't really know what normal is until you take the problem away.

Who else would you want to hear interviewed about being wrong?

What about George Bush? I tend to be pretty right-wing, and I have to say most people that I associate with at the university are a bunch of lefties, including my wife. But it's going to be interesting over the next 20 or 30 years to see how history judges George Bush, and how the Middle East will turn out. It probably takes generations for those things to change. But you provide a bit of stability, a bit of education for women, Internet, cell phones, travel — it's very difficult to keep a country all locked up after that.

This blog features Q&As in which notable people discuss their relationship to being wrong. You can read past interviews with Innocence Project Co-Founder Peter Neufeld , marriage counselor Harville Hendrix , Google research director  Peter Norvig , Wikipedia co-founder  Larry Sanger , NASA astronaut-turned-medical-error-guru  James Bagian , hedge-fund manager  Victor Niederhoffer , mountaineer  Ed Viesturs ,  This American Life  host  Ira Glass , celebrity chef  Anthony Bourdain ,  Sports Illustrated  senior writer  Joe Posnanski , education scholar and activist  Diane Ravitch , and criminal defense lawyer and pundit  Alan Dershowitz .

In the spring of 1981, a 12-year-old boy was beaten and forced to watch as his 11-year-old female cousin was raped by a stranger in a park in Cleveland, Ohio. Several weeks later, a man named Raymond Towler was stopped by a ranger for running a stop sign in the same park and brought into the police station for questioning. * After hesitating for 10 and 15 minutes, respectively, both the boy and the girl eventually chose Towler's picture from a photo array. On the basis of that identification, and despite testimony by multiple witnesses that Towler had been home at the time of the crime, he was convicted and sentenced to life in prison. This May, after 28 years behind bars, Towler was exonerated when DNA evidence showed that he was not the girl's rapist. He was 24 on the day he was convicted and 52 on the day he walked out of prison.

With his exoneration, Towler became the 258th person to be freed by the Innocence Project . Founded in 1992 by Peter Neufeld and Barry Scheck, the Innocence Project uses DNA evidence to overturn wrongful convictions while also advocating for reforms to the criminal justice system to help prevent future mistakes. In the interview below, I speak with Neufeld about the origins of wrongful convictions, how police and prosecutors face up to their mistakes (or don't), and why he doesn't speculate about the outcome of his cases anymore.

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How do most wrongful convictions come about?

The primary cause is mistaken identification. Actually, I wouldn't call it mistaken identification; I'd call it misidentification, because you often find that there was some sort of misconduct by the police. In a lot of cases, the victim initially wasn't so sure. And then the police say, "Oh, no, you got the right guy. In fact, we think he's done two others that we just couldn't get him for." Or: "Yup, that's who we thought it was all along, great call."

It's disturbing that misidentifications still play such a large role in wrongful convictions, given that we've known about the fallibility of eyewitness testimony for over a century.

In terms of empirical studies, that's right. And 30 or 40 years ago, the Supreme Court acknowledged that eyewitness identification is problematic and can lead to wrongful convictions. The trouble is, it instructed lower courts to determine the validity of eyewitness testimony based on a lot of factors that are irrelevant, like the certainty of the witness. But the certainty you express [in court] a year and half later has nothing to do with how certain you felt two days after the event when you picked the photograph out of the array or picked the guy out of the lineup. You become more certain over time; that's just the way the mind works. With the passage of time, your story becomes your reality. You get wedded to your own version.

And the police participate in this. They show the victim the same picture again and again to prepare her for the trial. So at a certain point you're no longer remembering the event; you're just remembering this picture that you keep seeing.

Other than misidentifications, what other factors play a role in wrongful convictions?

The second most common cause is the misuse of forensic science other than DNA. In most of our cases, DNA [identification] didn't exist at the time of the conviction, so prosecutors relied on other types of forensic science. It could be serology, which was the old A/B/O blood typing. It could be bite marks. It could be fingerprints. It could be other forensic disciplines: tire marks, shoe print comparisons, fiber comparisons. None of these is bulletproof — some of them aren't even credible — so we see a lot of wrongful convictions stemming from those.

And there are several other very common causes as well. You have police and prosecutor misconduct. You have incompetent defense attorneys. You have jailhouse snitches, who as you can imagine are not the most reliable sources. And you have false confessions. Twenty-five percent of wrongful convictions involve false confessions. Most people can't imagine why anyone would ever confess to a crime they didn't commit, unless they were beaten into it. But these people weren't beaten. They wouldn't even meet the legal definition of coercion. It's just that the [interrogation] methods that are effective for getting confessions from guilty persons are so powerful that they net innocent people as well — particularly innocent people who are juveniles or have some kind of intellectual impairment or mental health problem.

I'm curious about police and prosecutor misconduct. I assume that most people in these jobs aren't actually trying to convict innocent people. So how does such misconduct come about?

I think what happens is that prosecutors and police think they've got the right guy, and consequently they think it's OK to cut corners or control the game a little bit to make sure he's convicted. The thinking goes, "God forbid a guilty guy go free because of smart lawyering by the defense" or what have you. They're so convinced that they are right that they feel exempt from behaving right. They don't realize that it's wrong to be unethical. And not just because it could convict an innocent person. It's simply wrong to be unethical.

How do prosecutors typically respond to the work of the Innocence Project, given that you're essentially challenging the validity and quality of their work?

You can divide prosecutors into two classes: those who believe in DNA wholeheartedly and want to cooperate with us, and those who oppose us. There's still a whole category of prosecutors and detectives who say, "No, I'm sure [the guy I convicted] is guilty. I can't tell you how, I can't give you a logical explanation, but he's guilty."

What's scary is that these people are part of a system that's predicated on logic and reasoning to see that justice is done. Yet they will ignore all logic and reason to protect their egos and their psyches. And it requires a complete disconnect, too, because these guys rely on DNA to convict bad guys all the time. But when the DNA works against them, they say something must have gone wrong.

Can you give me an example?

We took a deposition last week of a guy who was the lead detective in the prosecution of a young man named Jeffrey Deskovic . Jeff Deskovic was a 16-year-old white kid in Peekskill, N.Y., with no criminal record, when a 15-year-old girl was raped and murdered on her way home from school. This was in 1990. Jeffrey went to the police and said, "I knew her, I liked her, is there's anything I can do to help you solve this crime?" Well, the detective he spoke to had been told by somebody in the police academy that people who commit crimes often come forward offering to help. So this guy locked his sights on Jeffrey and after multiple encounters, the kid confesses. They then did DNA testing on the semen recovered from the girl, and Jeffrey was excluded. But [the prosecutors] never disclosed that; they simply dropped the rape charge and argued at trial that she must have had consensual sex with somebody else and Jeffrey was the murderer. Twenty-five years later, we took that DNA profile and ran it through the convinced felons database, and the profile of the semen matched a serial rape-murderer who was serving life in prison for attacking and killing another teenage girl in another town in Westchester a year and a half after the victim in Jeff's case was killed.

Given that factual backdrop, you'd think that people would say, "You're right, we made a terrible, terrible error, we investigated the case incorrectly, and it led to this tragic result." But no. Even with the DNA evidence, even though the serial murder-rapist gave a full, detailed confession and provided all kinds of details that no one knew, but the real perpetrator could know, this detective just last week said, "I'm sorry, that's ridiculous, Jeffrey Deskovic is guilty. The only false confession in this whole matter is the false confession given by the serial rape-murderer."

Would you say that detective was an outlier, or is that kind of denial routine?

I'd say, just based on my own experience, that about half the time police and prosecutors bury their heads in the sand and insist that they were right no matter what the evidence says. Look at the New York City police in the Central Park jogger case. It's right on point. They're in terminal denial. They still haven't got any insight. A woman is viciously attacked by somebody, raped, and left for dead. Five kids are picked up in the park that night, they're all interrogated, the interrogations are not recorded but the ultimate confessions are. Later the kids say the confessions were coerced and that they're innocent, but they get convicted.

Years later, DNA testing shows that some other guy who had three rape convictions and didn't know any of these kids committed this rape. Everyone in the DA's office who did the investigation has now concluded that this guy acted alone, and they vacated the convictions [of the youth]. The police department hired their own experts to write a bogus report saying, "The DAs were wrong, our confessions were valid, these guys must have been involved." They just can't get beyond that. It's remarkable.

This isn't the first time I've heard stories like this, but I never stop being disturbed by that degree of denial, given the seriousness of the stakes.

It is disturbing. But the truth is, when I run up against this, I don't worry for our clients. Our clients are going to get out. They've got the testing. A prosecutor can say the earth is flat until the cows come home, and eventually we're going to prevail.

What's troubling are all the people who we haven't done testing for, or for whom there's no biological evidence. If a prosecutor or a detective is totally unable to admit they're wrong in one case, what that tells you is that they will be making dozens and dozens more erroneous decisions, because they're not allowing new information to affect their views. If you can't admit you're wrong, you should just stay home and knit sweaters. You shouldn't be involved with any occupation where your decision-making can have an impact on other people's health, life, or liberty.

Stated that way, it sounds like the problem boils down to specific individuals. Do you think that's the issue — so called "bad apples" — or do you think there's something about the legal system or the psychology of what happens when you get involved with a wrongful conviction that actually makes a lot of people resort to denial?

I don't think it's specific to the legal system. I think generally speaking it's difficult for people to admit they're wrong, and the higher the stakes, the more difficult it becomes. So what you really want to do is educate people that it's OK to be wrong. It doesn't mean you're a fool. It's not going to be the end of your life.

I'll give you an example. I'm on the board of a medical center and a medical school, and I've watched the culture of medicine change somewhat over the last 20 years. It used to be much more difficult for doctors to admit error; they would hold on to their original beliefs and were completely inflexible. Today many more people understand that if you do an investigation into a medical error, the individuals involved are not going to be taken out and hung. They're not going to be fired. They're not even necessarily going to be sued. Instead, you'll use what you learn from those errors to improve the system. And through that I've noticed a much greater willingness on the part of health care providers to admit error and move on.

Is there any analogous shift happening in the law?

No. In the criminal justice system, the culture hasn't changed. We don't have inquiries when wrongful convictions occur; they just happen and that's the end of it. We should have a system in place where you do audits when you get a wrongful conviction — where you look at a person's body of work to see if this was a one-off situation or there was evidence of a systemic defect, either with an individual, with a police department, or with a way of doing things. If you could show people that what you were going to do with this data was simply improve the system, I think the culture would change and people would be more willing to admit they were wrong.

What about legislative shifts? As the fallibility of these various investigative tools becomes more obvious, is the legal system starting to implement reforms?

The only way you get national change is through a Supreme Court decision or an act of Congress. But we are moving incrementally to get reforms implemented in a city here, a state there. But it's certainly not the vast majority. It's not even a sizeable minority. It's a few. There's a great deal of resistance because people don't want oversight. Nobody likes oversight, even though we all need it.

In those localities that have implemented reforms, what happened to prompt that change?

It usually takes a kind of perfect storm. You'll have some very compelling narratives of wrongful conviction. You'll have very progressive leadership in the legislature. You'll have a forward-thinking police chief or prosecutor who gets it and wants to be ahead of the curve. But there's only a couple of state legislatures that have introduced these kinds of reforms. Ohio and Vermont gave us reform packages in the last 12 months. New Jersey did it several years ago. That's about it for states. For individual counties or cities, there's a few dozen in the country.

I think many Americans have this perception that our legal system is basically sound and trustworthy, and that wrongful convictions are anomalous. How right or wrong is that perception? To what extent do the 258 wrongful convictions to date reflect the scope of the problem?

The 258 figure is unquestionably just the tip of the iceberg. In many of our cases, the biological evidence has been lost or destroyed in the intervening years, so clearly our exoneration numbers would be much, much, much higher if we could bring more cases to lab. Over the years, our exclusion rate [in which the DNA result excludes the convict as a possible perpetrator of the crime] has been about 50 percent. That's not to suggest that the false conviction rate is 50 percent, because obviously we have a self-selecting data set of people who write to us and claim to be innocent.

Similarly, for 20 years, the FBI has been keeping data on cases that get sent to them by local law enforcement agencies for testing. These are cases where a prime suspect has already been identified based on other kinds of evidence — a confession, an ID, circumstantial evidence, whatever. Over the years, they've had a 25 percent exclusion rate; one-quarter of all initial prime suspects are excluded based on DNA. Now, that, too, doesn't mean the wrongful conviction rate is 25 percent, because some percentage of those cases would have been either dismissed or acquitted even if there hadn't been DNA testing (although the acquittal rate is very low in this country). But what these numbers tell you is that, my God, there are a lot of people in prison from before DNA evidence who are innocent.

Are those numbers dwindling now that DNA testing is routine?

Well, it's certainly better to have DNA testing than not, but it's a misperception to imagine that it's going to solve the problem. People think, "Oh, now we have DNA evidence, so this issue will gradually disappear." The truth is it doesn't disappear, because you can only use DNA testing in a small minority of violent crimes. If there's a drive-by shooting, there is no blood left behind. If there's a robbery, there is no semen left behind. In many crimes, police departments have to rely on less reliable means of investigation to decide who to prosecute.

That's why we have these recommendations for reforms, because we know that DNA alone is not going to solve the problem. Unless we change some of these other root causes of wrongful conviction and make the process more reliable, we will continue to wrongfully convict people at alarming rates.

Do you think working on these issues for so long as changed your own attitude toward rightness and wrongness?

Well, that and marriage. [Laughs] They've both made me much, much more willing to say, "I'm wrong."

I'll tell you something. One of the things we used to do at the Innocence Project is we would try, just informally, to predict which cases would end up being exonerations and which ones would end up confirming guilt when the DNA came back from the lab. And I was wrong more than I was right. What that tells me is that I was raised in the system before DNA evidence, where I relied on all these other types of investigative tools to determine guilt or innocence. That's one of the important things about DNA for me: It taught me how unreliable my own intuition is. Now when people say, "What do you think is going to happen?" I say, "Whatever happens happens, I have no idea and I don't want to speculate."

Last question. If you could hear anyone else interviewed about being wrong, who would it be?

Cheney or Rumsfeld.

They're popular choices.

Good. I like to know that I'm very mainstream.

* Correction, Aug. 18, 2010 : This article originally misidentified Raymond Towler as Raymond Fowler.

This blog features Q&As in which notable people discuss their relationship to being wrong. You can read past interviews with marriage counselor Harville Hendrix , Google research director  Peter Norvig , Wikipedia co-founder  Larry Sanger , NASA astronaut-turned-medical-error-guru  James Bagian , hedge-fund manager  Victor Niederhoffer , mountaineer  Ed Viesturs ,  This American Life  host  Ira Glass , celebrity chef  Anthony Bourdain ,  Sports Illustrated  senior writer  Joe Posnanski , education scholar and activist  Diane Ravitch , and criminal defense lawyer and pundit  Alan Dershowitz .

Whatever else you want to say about it, wrongness is a capacious subject. Since this blog began, I've interviewed people about the relationship between error and  medicine , encyclopedias ,  computers ,  space travel ,  corporate culture ,  hedge funds , mountain climbing , storytelling , Israel , omelets ,  education ,  Leona Helmsley , and  the Cleveland Indians , among many other subjects. And yet, somehow, I've yet to broach the issue of how our thoughts and feelings about wrongness affect one of the most important — maybe the most important — arena of human life. I'm talking, of course, about love.

Enter Harville Hendrix . Hendrix is the author of the best-selling  Getting the Love You Want , along with the also-best-selling  Keeping the Love You Find   and many other books. With his wife and business partner, Helen LaKelly Hunt, he pioneered the concept of "conscious partnership" and developed a form of counseling he calls  Imago Relationship Therapy . Oprah Winfrey, who has hosted Hendrix on her show 17 times, refers to him as "the marriage whisperer." I sought Hendrix out to ask him why most of us are so attached to being right and so threatened by being wrong — and what we can do to rethink those attitudes about wrongness to improve our relationships with our partners, our families, and ourselves.  

Thanks for agreeing to talk to me. I've been thinking a lot lately about the desire to be right and what a powerful effect — usually a negative one — it has on relationships.

It's a question that's very relevant to me and one I've thought about a lot. Every couple I see, both partners think they're right. And as you point out, that doesn't tend to go well. You know, there's an old phrase, "You can either be right or be in a relationship." Which really means you can either  insist  on being right—never mind whether you really are or not—or be in a relationship. 

Why do you think most of us are so insistent about being right?

There are two ways to think about that. One is a very natural and nonpathological analysis, which has to do with the way we are designed as human beings. I call it "concentric consciousness." For all of us, we are at the center of our own universe, and everything else is the periphery. So it makes sense that we think that the way we see things is the way they really are. That's natural. 

If we were talking about philosophy instead of psychology, we'd call that realism: the idea that the world is precisely as we perceive it to be. 

Exactly. There's a philosophical theory called the correspondence theory of truth, which pretty much describes most people's ordinary, everyday, nonreflective way of thinking about themselves and the world. Simply put, it means the belief that there is an exact correspondence between what I see and what's really out there: "My perspective is universal and what I see is what is real." That's a very real part of the human experience. 

And yet anyone in the intellectual history of the culture understands that there's no such thing as direct perceptions. That went out the window when Copernicus pointed out that the sun is at the center of the universe, not the earth. By the 15th century, philosophers understood that human perception involves interpretation, and that idea has been developed considerably by postmodern philosophers and psychologists. All we have is the capacity to interpret phenomena. We do not have access to the thing in itself, as Kant would have said. All we have is a representation of the thing, and that representation is clouded by our own subjectivity. 

Nonetheless, as you started out by saying, we often insist that we  do  have access to the thing in itself — that we're right and can know that we're right. Something tells me that a universal dose of Philosophy 101 wouldn't really solve the problem — that the underlying issue is largely emotional. 

Some people are wounded in childhood by an intrusive or neglectful parent, and that produces emotional pain, and emotional pain produces self-absorption. And when you are wounded and become self-absorbed, your natural inclination to see yourself as the center of the world and everything else as on the periphery is amplified to the point where you cannot be flexible with data. You can't actually take in new information very well. When you're wounded early, you organize the world in a certain way, in order to give yourself some sense of inner cohesion. You make up your mind about the way things are, who you are, who your parents are, and although that helps you survive, it also means you have all these very rigid ideas surrounding what is fundamentally a fragile inner core. 

And the experience of being wrong about those ideas threatens that inner core?

If you're wounded in some way, yes. You form all these perspectives, but for you, those perspectives are  not  perspectives. They're perceptions: the world as it really is. To have those perceptions turned into perspectives, which would be the healthy thing to do—that threatens your fragile internal organization. And because you rely on the stability of those perceptions—rather than on a stable self—to feel safe in the world, the idea that those perceptions are fallible produces huge amounts of anxiety. As I see it, one of the core reasons we can't admit to being wrong is that doing so threatens our internal cohesion and throws us into chaos. 

If you grow up in a healthy family, by contrast, you grow up with that same concentric consciousness, with the same correspondence theory of truth, but you have a solid core. You have flexibly, adaptability, you have the capacity to be curious, so when someone says, "Oh, I didn't like that movie," and you did, you can say, "Well, what  did  you think about it?" But if you're wounded and defended and scared, you just think, "Well, if you don't like that movie, that means you're wrong or stupid, because the way I see it is the way it is." 

I'm interested in this idea that having your perspective challenged produces anxiety. That comports with something another therapist said to me, which is that our capacity to tolerate being wrong hinges on our capacity to tolerate emotion. 

I think that's right. To entertain the possibility that you're wrong is to feel anxiety about your inner organization, as well as shame, embarrassment, and even guilt about the erroneous perspective. And shame and guilt are almost intolerable emotions. So in order not to experience that anxiety and shame and guilt, you become rigid in your perceptions. 

How does that rigidity play out in our relationships? 

Well, for starters, most couples do not know that the correspondence theory of truth is inaccurate. They don't think philosophically; they operate out of the idea that their experience is what's true. So they feel they have to diminish or devalue and sometimes even annihilate their partner's perspectives, because to see things from that person's point of view would mean you'd have to give up on the absolute truth of your own, and that would trigger anxiety and everything that follows from it—chaos and shame and guilt. So this adamant commitment to your own perceptions translates into destroying your partner's perceptions. Not that people are aware that this is what they're doing, of course; they think they're just defending the truth.

In Western culture, we have this narrative about romance in which falling in love is about finding a previously missing part of our self — our "better half," our "soul mate." Or, as Phil Collins put it, "two hearts living in just one mind." I assume that part of what's so difficult and uncomfortable about disagreement in relationships is that it constitutes a kind of implicit betrayal of that idea.

In the early stages of love, you actually do experience a kind of merger of consciousness. People who are falling in love seem to kind of fuse together for a while; you sort of surrender your own personhood. But at some point you differentiate. You say, "I am me and not you, and this is what I think and not that." And "Actually, I don't really enjoy that kind of movie," or "I really like butter pecan ice cream better than vanilla, even though it was fun to eat it with you sometimes." For the other person, it's like: "You really think that? Did you lie to me?" But nobody lied. There's a kind of collusion in romantic love not to breach reality. 

You know, it reminds me on a personal scale of something that happens on a political scale of well. I'm thinking of utopias — how we have this dream of a perfect society characterized by unanimity and perfection but, in fact, utopias tend to either fall apart or turn disastrous fairly quickly. Whereas if you accept that differences of opinion exist instead of trying to eradicate them, you can achieve a more stable society. It sounds like the same goes for relationships — that the dream of unanimity and perfection is ultimately destructive.

It is destructive because it is impossible. None of us share our partner's perspectives in every detail, and the power struggle that happens after the romantic phase is always triggered by something showing up in the relationship—in  the person's behavior or belief or thought or action—that you had denied or overlooked, or that the other person had withheld. That's what produces the tension that puts people into conflict. And then you go into polarity: "I'm right." "No, I'm right."; "You did that." "No, I didn't." "Yes, you did." 

This process that couples go through is what I call negation of each other. They don't really consciously know that when they say, "That's not what you said," or "That's not right," or "That's so stupid," that in fact they're annihilating each other, but they are.  And they do it over and over and over again. You just get annihilation and counter-annihilation until they reach an impasse when they can't talk anymore. And that's what comes walking into our offices. They can't resolve that. 

Can you break down this idea of negation and annihilation for me? What specifically happens for people emotionally when these kinds of disagreements appear in relationships? 

I think the first emotion is anxiety. When people begin to finally get it that, "Oh, he really does like butter pecan ice cream" or "He really does have that thought," that triggers enormous anxiety. Anxiety is the motivating feeling that comes up behind all the other ones—bargaining, anger, depression, everything. 

How would you define anxiety?

Anxiety is the anticipation of danger. Fear is the experience of danger: You see a tiger in front of you, you have a fear reaction, you do whatever you need to do to protect yourself, which is usually to run or hide.  Anxiety is the fear that the catastrophic is  going to happen. If I suddenly discover that my partner has had an affair, I anticipate all kinds of catastrophic consequences: I will lose this relationship, I will lose my security, I will lose my status in the community, I will maybe lose my children. All kinds of catastrophic scenarios come to mind, depending on your own fears and also your own value system. But it's all a forward projection. Fear is the experience of the present being dangerous. Anxiety is fear of the future. 

Got it. So once people's anxiety is triggered by these disagreements, what happens next?

Typically the anxiety is followed by anger. Anger is an attempt to coerce a person into surrendering their reality, so that there's only one reality in the relationship instead of two. And when the anger triggered by the anxiety doesn't work, people experience depression.  Depression is the experience of the loss of power: "I can't make my world happen." 

Once they go into depression, couples—if they stay together—will then enter a bargaining stage. The bargaining goes like this: "Well, OK, I'm different and you're different, so let's make a deal about whose reality is going to be in the forefront."  It's like, "Okay, you're a Baptist and I'm an Episcopalian, so we'll go to a Baptist church one Sunday and an Episcopalian church the next Sunday." They're trying to orchestrate a kind of interchange of realities, and they often think that this is a really enlightened move and the one that should and will save their relationship. So when it doesn't work, people go into despair. And then they come to me hoping that I will help them make better deals. But making better deals never works, because deal-making still involves giving up some part of yourself.

So what do you do with couples that have reached that point?

With my wife, Helen Hunt, I developed Imago relationship therapy , and as part of that, we have developed a process we call "dialogue." Dialogue is a generic word, but we have a special structure for it; we call it mirroring, validating, and being empathic. And what we've found over the years is that, with couples, you have to hold them in the process and give them some coaching in learning to listen. People have to learn to listen and listen and listen and listen until they finally get it that their partner has their own inner world—that you like apples and your partner likes oranges and that it's okay to like oranges. 

One of my axioms is that if you want to be in a relationship, you have to get it that you live with another person. That person isn't you. She's not merged with you. She's not your picture of who she is. She doesn't live inside your mind. She doesn't know what you're thinking, and you don't know what she's thinking. So you have to back off and move from reactivity to curiosity. You have to ask questions. You have to listen.

It sounds like you're not just coaching people to accept their role in any given disagreement — like, "OK, maybe how I react to my in-laws isn't fair, maybe my partner has a point." You're asking them to accept disagreement in general, without automatically interpreting it as rejection or creating friction around it. That's a pretty tall order. Not to put too fine a point on it, but: Does it work?

We find that over time, if they're in a safe and regular environment, most couples can begin to tolerate difference instead of seeing it as bad. That's when we see them moving toward health. And then when they stay in that process and discover that nothing catastrophic occurs when you accept that what your partner says is true  for them , the anxiety relaxes. That's when you know you're getting to more solid ground:  when people move to, "Well, tell me more about that, I'm really curious: What is it like for you to think that or feel that or do that? What's going on when you're late and don't call?" Curiosity then becomes a bonding experience, and that can then lead to excitement and to wonder: "Gee whiz, I have two worlds: I have my world and your world, and both of them are right, and we no longer have to be in a power struggle about it. We can be in mutual acceptance."

I will say, though, that I've never found anyone willing to surrender their perceptions until they're in a safe environment—unless they are absolutely forced to do so because reality crashes in on them in some dramatic way: because they learn that their husband or wife has an affair or has embezzled a bunch of money or what have you. 

Let's talk about those kinds of situations, because they're some of the most dramatic experiences of wrongness most of us will ever experience. Not many of us will ever be involved in, say, a wrongful conviction, but a whole lot of us get cheated on or get betrayed or just generally invest our trust in an untrustworthy person and suffer the consequences. In your experience, how do people respond to this kind of dramatic collapse of an emotional belief?

The first thing that happens is shock, of course—enormous shock that an unwanted reality is in fact true. In a catastrophe like divorce, it's particularly shocking because that's the one thing that seems to rupture what we would call the attachment impulse the most. Attachment is so necessary and central to our sense of trust and safety in relationships, so when that attachment bond is ruptured, it's hugely anxiety-provoking. People do all kinds of crazy things in order to protect themselves from the pain of the rupture. 

If the catastrophic discovery is something like, your partner has three kids in another city, you can't make that reality go away, so you go into depression. But again, I think the operative word here is anxiety. Unpredicted realities produce enormous amounts of anxiety for most people. What you do with that anxiety depends on your mental health and your level of maturity. If you're mature, you may find it a problem to be solved rather than a catastrophe. But it takes very healthy people to do that, and we don't have a whole lot of those people on the planet yet.  

Speaking of all the other people on the planet, if you could hear any one of them interviewed about being wrong, who would it be?

George W. Bush.

Kathryn Schulz  is the author of  Being Wrong: Adventures in the Margin of Error . She can be reached at  kathryn@beingwrongbook.com . You can follow her on Facebook  here , and on Twitter  here .

This blog features Q&As in which notable people discuss their relationship to being wrong. You can read past interviews with Google research director  Peter Norvig , Wikipedia co-founder  Larry Sanger , NASA astronaut-turned-medical-error-guru  James Bagian , hedge-fund manager  Victor Niederhoffer , mountaineer  Ed Viesturs ,  This American Life  host  Ira Glass , celebrity chef  Anthony Bourdain ,  Sports Illustrated  senior writer  Joe Posnanski , education scholar and activist  Diane Ravitch , and criminal defense lawyer and pundit  Alan Dershowitz .

Google, the company, entered this world in 1998. I'm not sure how long it took for Google , the verb, to follow — but I do know that millions of people engage in that particular activity many, many times each day. For half of all Internet users worldwide, Google is the portal to the collected and digitized wisdom (and folly) of humanity. Google's search engine has changed how we conduct research, plan vacations, resolve arguments, find old acquaintances, and check out potential mates. It's also given us new ways to interact with maps, mail, books, news, and documents, radically reshaping the way we think about almost every imaginable medium. 

Peter Norvig, the director of research at Google, has been involved in this project since its toddlerhood. Norvig joined the company in 2001 and, from 2002 to 2005, served as its director of search quality — a position that put him charge of the company's core Web search algorithms.  Below, he and I talk about (among other things) how engineers think about error, what's good about failing fast, and why Google buys cheap computers.

***

I'm interested in the way that attitudes about error vary across professional cultures — doctors typically think about error very differently than pilots and politicians and so forth — as well as across the cultures of different companies, even within the same field. How would you characterize the overall attitude toward error at Google?

There's a story going back to the founding of Google: One of the venture capitalists came to [company founders] Larry [Page] and Sergey [Brin] and said "OK, the first thing you have to decide is, is this company going to be run by sales or by marketing? They said, "We think we'll take engineering." He laughed and said, "Oh, you naive college kids, that's not the way the real world works." And they said, "Well, we want to try it." Ten years later, that experiment is still running; engineering is still the center of the company. And it seems like it's worked.  

And, like you say, it does create a very different attitude toward error. If you're a politician, admitting you're wrong is a weakness, but if you're an engineer, you essentially want to be wrong half the time. If you do experiments and you're always right, then you aren't getting enough information out of those experiments. You want your experiment to be like the flip of a coin: You have no idea if it is going to come up heads or tails. You want to not know what the results are going to be.

What about errors not in experimentation but in implementation or execution? What do you do about mistakes like that, which can presumably compromise your product?

As an engineer, you're just used to the idea that there are errors. No matter how good you think you are, the industry standard is that if you write 100 lines of program, there's probably going to be one error in it. So you have to build all your systems expecting that. We built an entire development process around the idea that errors exist and the need to minimize their impact.

What does that process look like?

Well, first, there are two kinds of error we deal with. One is, there's a clear error in the code: It's supposed to do one thing and it does something else. In that case, you know when you've got it wrong, and you'll know when you've got it right. The second is, how good are the results? Say you do a search and it shows you links; there is no definitive right or wrong to the question of, "Did it work?" But you can say, "Well, this one worked better than that one."

That's interesting. Thomas Kuhn, the great historian and philosopher of science, makes a similar point — that you can't say whether an individual theory is right, you can only say which of two theories fits the facts better.

Right. And we test at both levels — the clear-cut case where it's wrong, as well as the one where you're trying to figure out what works better. At the first level — and we share this with most software companies — before anyone can check in a piece of code that they've written, somebody else has to sign off on it. And then we have all these review processes and test processes at multiple levels to see if [your code] gives the right answer. A large proportion of the code you write is testing what somebody else wrote or what you yourself wrote. The work you're doing is often about, "Am I getting the right answer?" rather than, "How do I compute the right answer?"

What do you do about technological failures? I assume that sometimes it's not the software but the hardware that goes wrong and that the price of those problems can be pretty steep.

I think Google was early in accepting hardware errors. Other companies have tried to say, "Well, if you can buy big, expensive computers that are more reliable, then you'll have fewer breakdowns and you'll do better." Google decided to buy lots of cheap computers that break down all the time, but because they're so much cheaper, you can design the system with multiple backups and ways to route around problems and so forth. We just architect the system to expect failure. Google was very innovative in this area and saved a lot of money as a result.

How did that innovation come about?

In part, I think it was visionary. But, in part, it was just that the problem we are attacking made it easier. If you're doing a Web query and some of the computers break in the middle and you don't get exactly the same result as someone else doing the same query, well, OK. You don't want to drop the top result; if I do a search of the New York Times , I want nytimes.com to be the top result. But what should the 10th result be? There is no right answer to that. If a hardware error means we dropped one result and somebody had a different result at No. 10, there's no way of saying that's right or wrong. Whereas if I'm a bank, I can't say, "Oh, one out of every million transactions, I'm just going to lose that money." I can't have that level of failure. But at a search company, you're more tolerant of error.  

I've been at both ends. My previous job was at NASA, where you really don't want your shuttles to blow up very often. So there they spend hundreds of millions of dollars to protect their astronauts' lives. Here, we're kind of at the other end. Failure is always an option at Google.

I want to talk about innovation, because it seems to me that the price of trying new things is that most of them fail. How do you build a tolerance for that kind of failure into a public corporation that's accountable to its bottom line? Getting things wrong might be necessary to getting things right, but failure can be costly.

We do it by trying to fail faster and smaller. The average cycle for getting something done at Google is more like three months than three years. And the average team size is small, so if we have a new idea, we don't have to go through the political lobbying of saying, "Can we have 50 people to work on this?" Instead, it's more done bottom up: Two or three people get together and say, "Hey, I want to work on this." They don't need permission from the top level to get it started because it's just a couple of people; it's kind of off the books.

Two or three months isn't very much time. How do you decide at that point whether an idea is going to succeed or fail?

When you talk about being wrong, I think of that mostly from a statistical inference point of view, and within the company, we're really good at making decisions based on statistics. So if we have an idea — "You know, here's a way I can make search better" — we're really good at saying, "Well, let's do an experiment. Let's compare the old way with the new way and try it out on some sample searches." And we'll come back with a number and we'll know if it's better and how much better and so on. That's our bread and butter.

OK, but what about things that can't be measured experimentally?

Right, that's the question. When it comes to something that doesn't really have statistics, that's harder for us. Take something like launching Gmail, where it wasn't a question of, "Can we make it work?" It was a question of, "Well, gee, who are the other players in this game?" It was Microsoft, Yahoo, and AOL, and they were all either partners or rivals or both to us, so then the question is, "How are they going to react if we do this?" And we had this idea to offer it for free but to have ads on the sides, so it was like: "Are people going to think that's creepy?"

You can't really do experiments for things like that; you can't get at it through statistics. I suppose you can have focus groups, but focus groups really aren't important; it's more about what the press is going to say. So those types of decisions have to be made more on gut instinct rather than a statistical basis. And as a company, that's harder for us.

Can you parse the idea of gut instinct for me? What is it? What are you actually relying on when you make those so-called instinctive decisions?

Good question. I guess it's experience. It's projecting into the future based on what you've done in the past. Is this going to work? Are we going to be able to build it on time? Is it going to perform as expected? You get a feel for things like that by having built similar projects.

The harder part, I think, is judging the likely reaction. Yes, we can build this, but are people going to like it? Or: Is somebody else going to build a better one first? Or: How are other companies going to react to this? I guess that's also an experience thing, but that part's much harder, because it involves not just what we can do, but how other people are going to respond to what we can do.

So how good would you say your gut instinct is? When you fall in love with an idea or a project — when your intuition says, "We should go for this, this is going to work" — are you usually right?

I think we often have good intuition about where things are going in general. As a company, we made a big bet on mobile and the Android platform because we knew that people were going to be using their phones rather than their desktops for computing, and that gamble worked out. But the details —w as creating the android platform the right way to do it? Should we have partnered with someone else or created a different system? — that was harder to say. A lot of the time, the strategic ideas are clear, but how to get there is not.

Earlier in this series, I interviewed Ira Glass , the host of This American Life , and he said that for every story we hear on the show, they start developing 10 or so and go into production on three or four. He also talked about sitting in on a meeting at The Onion and learning that they kill 30 or 40 pretty funny headlines in order to generate one really funny one. What about you guys? What would you say is your failure-to-success rate?

It's hard to say, because it varies a lot. Some teams are taking on projects that they pretty much know can be done. Let's say you've got some storage system that's not fast enough or big enough and we need to design one that's going to be better. Essentially we have to build that; we have no other choice. So we know it's going to get done. Maybe it won't quite meet the specifications — maybe it takes a little too long and maybe it's not quite as fast — but it gets done. So there you have a very high rate.

Then with things like search quality, we have all these ideas of how to make search better, and I'd say maybe half of those end up working. Sometimes you start down a path and then you find out it doesn't help, it doesn't make any difference.

Half strikes me as a pretty good ratio. What about the success rate for the kinds of experiments your users see, like all the stuff in Google Labs ? Do those catch on fairly often, or is it mostly like, "Well, that was a nice idea."

Most of the things you see in Google Labs are there because we didn't quite know what to do with them, so certainly less than half of them become hits. I don't know what the exact number is. Some of them are already winnowed out by the time they get there; if we thought they were really big, they'd be on the main site rather than the Labs site. Some of them are there because it was easier; maybe there's a security issue or brand-image issue with making it part of the main site, and we didn't want to go through that process if we don't have to. So we said, "Well let's throws it on Labs and if it becomes really popular, we'll think about how to integrate it."

Despite all the experiments Google has initiated since it began, the vast majority of your profits — I've heard between 97 percent and 99 percent — come from just one thing: advertisements related to search. Obviously, then, income generation is not the metric you're using to decide if a product succeeds or fails. What is?

You're right that most of the money comes in through ads. But you can think of everything else as bringing in customers so that they'll click on the ads. We know the value of adding a new customer, and we can see what the usage is of individual sites. So we can say, "This feature is popular, our usage is going up, and because usage is going up, we're making more money." We do things to make Google better so people will come to Google and click on the ads.

What's interesting, though, is that we're now at the scale where we can also do things that just make the Web better. We do a lot of open-source projects, because if we release code and some other company makes something really cool that makes the Internet better, we benefit, too. About half of Internet users are using Google search, so if another company builds something and two people start using the Internet because of it, we're going to get one of them.

Google has been remarkably successful at creating popular products. How does the company create a culture that's conducive to generating new ideas?

Well, we have great people, and that's a huge part of it. But I think the main thing is just trying a lot of ideas. We've built the ultimate system for making demos internally. If a startup company has an idea, it's like, "Well, I need a copy of the Web to make my idea work, I need a thousand computers, I gotta go raise money to do that." So they spend months or years raising money and building infrastructure.

Whereas we have all of that. Somebody can learn how to use it in their first day and say, "OK, I have an idea, and these pieces are already here, and I can just connect them together and see if it works." And if it doesn't work today, next week I'll have another idea. And I haven't wasted months going down one path. It's like playing with tinker toys or something. You plug 'em together, you try something, and if you think it's good, you keep going. And if it isn't, you put them down and start on something new.

I'm struck by how long some products stay in beta testing at Google. Gmail, for instance, was launched in 2004 but wasn't upgraded from beta status until 2009, by which point it had 146 million users. What's the reasoning behind that?

There's two parts to that, a technical engineering part and a public relations part. From the technical engineering point of view, you define a project and say, "These are the features this should have, and until it has all those features, it's still beta." But then there's another decision which is: When is it worth launching? Something can be missing a couple of features and still be worth launching, and we've chosen to do it that way, whereas other companies seem less likely to do so. I don't know why the PR people are open to that here. Maybe it gives the impression that Google is always changing and products aren't quite finished. And maybe they want to give that impression.

The whole beta model is completely at odds with conventional production and manufacturing; you never see General Motors release a beta version of a car, for instance. What's the cost-benefit tradeoff involved in releasing versions of products that you know are still flawed and incomplete?

There's a big difference between the products we have, which mostly live on our servers where we have the ability to update them every day, and a car, which once you ship out becomes very expensive to recall. Traditional software is somewhere in between; if you're selling CDs that you put in boxes and ship to stores, there's a cost to updating that, but it's less than the cost of a car. But for us, it's a process of continual change. We expect to change our servers every day; that's natural for us.

Is part of the benefit to you the open-source advantage — the fact that your customers find the flaws for you?

Yeah, sure, both explicitly — in terms of them saying, "Hey, here's a problem," and also implicitly, in terms of how they interact with it. We see the statistics, we measure how often they click on the first result, how often they have to do a follow-up search, and we get an idea of whether they're satisfied or not. And then we make a change and see if the statistics look better.

Last week in this column, I spoke with Wikipedia co-founder Larry Sanger about how we use the Web to organize, validate, and disseminate information. Google's stated mission is to organize the world's information. Does the company do anything to prioritize more accurate or at least more credible results in its searches?

In a sense, the core innovation behind Google — this notion of page rank, of how many other people are pointing to your result — is a crude measure of credibility. And that came about because of frustration with the quality of the results yielded by earlier search engines. The first search engines were built on a kind of library-sciences technology: To do a search, you looked for documents that mention those key words the most times. So you would often end up with results that were off-target but happened to have a high density of the keywords. Page rank said: If everyone else is pointing to this page, it must be a good one.

That's still how it works to a degree, but multiple things have happened since then. One is that now there's a war between the good guys and the spammers — people who are trying to artificially inflate certain pages by reverse — engineering our system and building pages that can falsely claim credibility. So we have to watch out for that. And then part of the problem with credibility by citation is that it takes time. You don't instantly gather links the first day something is published, which makes it harder to follow new news items and so on. So we need a way to weigh the freshness of a new result versus the accumulation of credibility over time. But yes, we are always looking at quality and credibility as well as salience.

Interesting. It sounds like page rank uses consensus as a stand-in for credibility. That slippage is hardly unique to Google-all of us use consensus as a stand-in for credibility sometimes-but it can be pretty misleading.

Yeah, that's always a problem. One way we try to counter that is diversity. We haven't figured out any way to get around majority rules, so we want to show the most popular result first, but then after that, for the second one, you don't want something that's almost the same as the first. You prefer some diversity, so there's where minority views start coming in.

What do you think have been Google's biggest mistakes?

I can't speak for the whole company, but I guess not embracing the social aspects. Facebook came along and has been very successful, and I may have dismissed that early on. There was this initial feeling of, "Well, this is about real, valid information, and Facebook is more about celebrity gossip or something." I think I missed the fact that there is real importance to having a social network and getting these recommendations from friends. I might have been too focused on getting the facts and figures — to answer a query such as "What digital camera should I buy?" with the best reviews and facts, when some people might prefer to know "Oh, my friend Sally got that one; I'll just get the same thing." Maybe something isn't the right answer just because your friends like it, but there is something useful there, and that's a factor we have to weigh in along with the others.

What about you yourself — what have you personally been most wrong about?

One thing is how fast things change. I was in a meeting a while ago and somebody was discussing a new project — this was in an area I hadn't touched for a while — and I said "Oh, isn't it the case that such and such?" And they kind of snorted derisively and said, "Yeah, well, that's the way the Web was four years ago, but that approach doesn't work anymore." I think that's happening constantly. You think you have this experience — and we talked about how important experience is for having intuitions — but experience can go out of date very quickly.

If you could hear someone else interviewed about being wrong, who would it be?

Last night I saw Jeff Ma speak — he's the MIT student who did the card-counting in Vegas, which the movie 21 was about. He talked about one of his first days betting and how there are certain situations where the statistics say, "If you're in this position, you should double your bet." So Ma finds himself in that position and doubles his bet and then the dealer deals himself 21 and Ma loses $50,000. Then a couple of hands later he was in the same situation and now he's down $100,000. So he went back to his room and said, "What did I do wrong?" He thought about it and said, "I didn't do anything wrong; the statistics are what they are and I did the exact right play for the statistics. The dealer just got lucky." So he went back and kept playing the same strategy and ended up winning $70,000 or something over the weekend. He makes the point that if you're making the right decision, even if you get a bad result, you're not really wrong.

And if I could interview a dead guy — and automatically improve my French, while we're wishing for the impossible — I'd take [French mathematician and astronomer Pierre Simon] Laplace. I think that he deserves most of the credit for Bayesian probability theory , and most of Bayes' fame comes from having his name on the theorem, not for actually doing the work.

Kathryn Schulz is the author of Being Wrong: Adventures in the Margin of Error . She can be reached at kathryn@beingwrongbook.com . You can follow her on Facebook here , and on Twitter here .

This blog features Q&As in which notable people discuss their relationship to being wrong. You can read past interviews with Wikipedia co-founder Larry Sanger , NASA astronaut-turned-medical-error-guru James Bagian , hedge-fund manager Victor Niederhoffer , mountaineer Ed Viesturs , This American Life host Ira Glass , celebrity chef Anthony Bourdain , Sports Illustrated senior writer Joe Posnanski , education scholar and activist Diane Ravitch , and criminal defense lawyer and pundit Alan Dershowitz .

After Google, Wikipedia might be the single most powerful new influence on how we as a culture organize, disseminate, and access information. For millions of Web-connected citizens, the online encyclopedia is the place of first resort for looking up everything from Shirley Sherrod to sickle-cell anemia . There's no question about its scope or popularity: It has 3.3 million articles in English alone (compare that to the roughly 120,000 articles in the online edition of the Encyclopedia Britannica ) and attracts nearly 78 million visitors each month. There's also no question that it's an astonishing triumph of open-source development: The entire colossus was built by a bunch of largely anonymous and entirely unpaid contributors.

There is, however, a great deal of argument — and consternation — about the accuracy of Wikipedia entries. (A headline in the Onion made the point nicely: "Wikipedia Celebrates 750 Years of American Independence.") That's why I went looking for Larry Sanger, who co-founded Wikipedia along with Jimmy Wales, then quit the project over disputes about its governance and the quality and credibility of its content. Sanger is also a trained philosopher with a focus on epistemology — the study of knowledge — which made him an attractive person to talk to about how technology is changing what we know, what we think we know, and how we think we know it. After leaving Wikipedia, Sanger founded Citizendium , a rival online encyclopedia, and now spends most of his time on WatchKnow , a nonprofit organization that uses wiki principles to organize and rate nearly 20,000 educational videos for kids.

What got you interested in encyclopedias? Did you have some kind of longstanding fascination with them, or was it just an accident of history?

It was pure accident. I was circulating an idea for a Web site around different Internet acquaintances and one of them happened to be Jimmy Wales. He responded by saying, "Well, I'm trying to get this encyclopedia project going; would you be interested in coming to work on it?"

That was Nupedia — he had registered the domain name, but at that point it was just an idea — and I got hired for that job. And then I found that it was a fascinating problem to organize people online to create encyclopedias.

People have been trying to validate, organize, and disseminate information for a long time. Did you look back to other efforts in history to do so?

When I was first starting Nupedia and Wikipedia, everything was moving so fast that I didn't have time to go back and read Diderot and D'Alembert and all that, which would have been useful. I did read them later. I can't remember when I read The Professor and the Madman , but that made a big impression me.

That's pretty funny, considering that it's a book about the relationship between the editor of a major reference work and a certified lunatic.

It actually resonated very much with the experience I had trying to organize Wikipedia. It's very interesting to me that here you have the editor of the Oxford English Dictionary , and one of his most prolific contributors was in an insane asylum. A lot of the most prolific Wikipedians, or at least many of them, also seem to have a screw loose. But that doesn't mean their work is useless.

Do you have a theory about this? Is there something about the project of organizing knowledge that attracts slightly nutty people? Or that turns normal people nuts?

There are a lot of theories on that, actually. But I think the most important thing to say is that Wikipedia has very few practical constraints about people behaving according to normal rules of politeness and fair dealing. They've got a zillion rules, of course — that's part of the problem — but there is no easy way to rein in the bad actors. And unfortunately the bad tend to drive out the good. A lot of the more sane, sensible people out there are just can't take too much of it.

Yeah, I can imagine that the social dynamics get pretty ugly. But my understanding is that you left Wikipedia over deeper philosophical schisms.

I had lots of deep philosophical schisms with Wikipedia in the end, although also some agreements.  The first problem was what we were just talking about: reining in all the bad actors, doing something to reduce the number of trolls and the amount of time we spent dealing with them.

The other problem was that there needed to be some sort of mechanism — it didn't have to be anything like editorships or review before publishing or anything like that — but some sort of low-key role for experts in the system.

Why did you feel so strongly about involving experts?

Because of the complete disregard for expert opinion among a group of amateurs working on a subject, and in particular because of their tendency to openly express contempt for experts. There was this attitude that experts should be disqualified [from participating] by the very fact that they had published on the subject — that because they had published, they were therefore biased. That frustrated me very much, to see that happening over and over again: experts essentially being driven away by people who didn't have any respect for those who make it their lives' work to know things.

Where do you think that contempt for expertise comes from? It's seems odd to be committed to a project that's all about sharing knowledge, yet dismiss those who've worked so hard to acquire it.

There's a whole worldview that's shared by many programmers — although not all of them, of course — and by many young intellectuals that I characterize as "epistemic egalitarianism." They're greatly offended by the idea that anyone might be regarded as more reliable on a given topic than everyone else. They feel that for everything to be as fair as possible and equal as possible, the only thing that ought to matter is the content [of a claim] itself, not its source.

It seems to me that this conflict between amateurs and experts boils down to a conflict between egalitarianism and credibility. You gestured toward this conflict in an essay on the Edge.com , where you wrote, "It's Truth versus Equality, and as much as I love Equality, if it comes down to choosing, I'm on the side of Truth." Do you find that it really is a zero-sum game — that, as a practical matter, we need to choose between these two goods?

I doubt very much that it's a zero-sum game. I think it's absolutely a great thing that people regardless of their credentials can contribute to the shaping of knowledge. And I think we have to creatively design ways of recognizing both the value of amateur work, on the one hand, and the objective value of the knowledge of people who are experts in various fields.

And that's what you were calling for at Wikipedia, right? For human experts to exert at least some baseline control over the content?

Well, I suppose. But you know, I don't like the word "control," because I myself am pretty libertarian in my outlook on these things, quite frankly. It makes me nervous to think of handing the keys over to the experts. But one thing that Wikipedia could do that would not spoil the system — except in the sense that it would cause a huge ruckus among Wikipedians — is simply create a program in which articles are reviewed or rated by experts.

This idea is not new. It's something that we discussed before I even left. It's sort of a perennial idea on Wikipedia, in fact, but they've never done it.

What would qualify someone as an expert?

Well, I can tell you how we do it on Citizendium. Generally we say that to contribute as an editor in a professional field, you need to have the credentials to practice in that field. So if you want to be an editor in law, then you should have a law degree and a few years of experiences. For more academic fields, we generally require a Ph.D.

None of that is to say that we aren't open to other people, but they have to establish their expertise up to that level in some other way. So if someone has a master's degree or even a bachelor's degree in history but has written a bunch of well-respected books — if there's enough evidence for another history editor to recognize the person as legitimate — then we would bring such a person onboard.

Have you read some of the criticisms of expertise that have come out in the last several years — for instance, Philip Tetlock's Expert Political Judgment: How Good Is It? How Can We Know? or, more recently, David Freedman's new book, Wrong: Why Experts Keep Failing Us and How to Know When Not to Trust Them ?

No, I'm afraid I haven't looked at those books.  I'd like to — they sound fascinating.

I suspect that most people who aren't involved in the making of Wikipedia, who interact with it as an end product, feel that it's basically good enough. They get that it's not perfect, but they have the impression that it's essentially pretty reliable. In your opinion, how right or wrong is that impression?

I think it's pretty dangerous to rely in an uncritical way on Wikipedia. Wikipedia frequently gets things wrong — or, more often, states things in a misleading or biased way. The problem isn't as bad in the hard sciences, but in the humanities and social sciences, certain views tend to come to the forefront, or the leading views on a subject are completely omitted or are left as a footnote. When it comes to subtly representing a dialectic, Wikipedia does a very bad job. But maybe people don't go to Wikipedia to try to master a debate.

What about factual matters? Are those reliable?

When it comes to just basic facts — statistics about geography or demographics, things like that — then as far I can tell, and as far as I've ever heard, those are fairly accurate. They are probably not much less reliable than any traditionally fact-checked source.

One of the ways we get things wrong is by belonging to a community that enforces, often tacitly, one set of beliefs while obscuring or rejecting another. Do you think Wikipedia constitutes a community in that sense, and if so, how would you describe its belief system?

If you're talking about political biases, I actually think that that's one of Wikipedia's least-worst problems. [Laughs] It's really not as bad as the people at, say, Conservapedia seem to think. I do think that there is a liberal bias on most topics where such a bias is possible, and I think that's probably a reflection of the fact that, again, the people who work the most on Wikipedia tend to be really comfortable with the most radically egalitarian views. And those people tend to be either liberals or libertarians.

I think the kind of biases that are in some ways more interesting and more pervasive have to do with individual biases not on political issues but on a host of very specific academic issues. An article can reflect the bias of a few people who just happen to be most motivated to work on it. This is a general problem with Wikipedia: What is praised as consensus decision-making or crowd-sourcing often just means that the person with the loudest voice or the most time on his or her hands is the one who's going to win.

Do you think that as information technology changes, the responsibility of getting it right is changing, too? Is the onus shifting away from the creator of information and toward the consumer?

I think the people who are putting the information out in front of an audience and presenting it as factual are the people who are responsible for it. Unless we're actually in there editing the articles, then it doesn't make sense to say that we have an obligation to make sure that the article reads the way it ought to read.

But maybe the question is, how ought we to read it? Should people use Wikipedia in the same way they would use, say, Encyclopedia Britannica, or do we need to start thinking and acting differently?

What Wikipedians themselves would say — and I agree with them on this one — is that Wikipedia has finally awakened in people an understanding that even carefully edited resources can frequently be wrong and have to be treated with skepticism and that ultimately we are responsible for what we believe. That means constantly going back and checking what we thought was established or what we thought we knew. Wikipedians often say that you should never trust any one source, including Wikipedia.

That's not anything new; it's always been the case that you should check your source against another source. It's just that the way that the Internet has exposed the editorial process has, for more critical-minded people, made it absolutely plain just how much responsibility we ourselves bear to believe the right thing.

Which online resources do you yourself turn to most often when you're looking for information?