Marx and Engels once remarked that "philosophy stands in the same relation to the study of the actual world as masturbation to sexual love." Just about everyone else who's written about philosophy has also criticized its lofty remove, except, of course, philosophers. And now the challenge is being mounted from within. Next month, the American Philosophical Association will convene a panel to confront its critics in the new movement known as "experimental philosophy," or "x-phi." Its practitioners are threatening to make a favorite method of traditional philosophers—asking yourself what everyone thinks—seem hopelessly outdated.
Philosophers have ignored the real world because it's messy, full of happenstance details and meaningless coincidences; philosophy, they argue, has achieved its successes by focusing on deducing universal truths from basic principles. X-phi, on the other hand, argues that philosophers need to ask people what and how they think. Traditional philosophy relies on certain intuitions, presented as "common sense," that are presumed to be shared by everyone. But are they?
For example, can people be morally responsible for their actions if they don't have free will? Many philosophers have assumed that all sane people would of course say no. Experimentalists don't assume. They ask. Recently, they presented the following scenario to two groups:
Bill and his wife were flying home from vacation with their friend Frank, who was having an affair with Bill's wife, as Bill knew. Kidnappers injected Bill with a drug that forced him to obey orders, then told him to shoot Frank in the head, which he did.
They told the first group that Bill wanted Frank dead and so grieved little for him. To the second, they said that Bill hated what he'd done. Both groups were then asked if Bill deserved blame for Frank's death.
Traditional philosophers have argued that Bill shouldn't be blamed in both cases because it's common sense that moral responsibility requires free will. But, in fact, the first x-phi group did blame Bill in the scenario in which he welcomed Frank's death. Similarly, groups praised a hypothetical involuntary organ donor, even though he had no choice but to give. This doesn't prove that you can have moral responsibility without free will. But it does vaporize a traditional philosophical objection to that view—that it lacks common sense.
Experimental philosophy is also challenging such basic philosophical notions as "intentional action." What do we mean when we say that someone did somethingintentionally? Most philosophers assume that we'd all agree that this is a question of the actor's state of mind. Experimentalist Joshua Knobe of the University of North Carolina at Chapel Hill asked college students: If a businessman interested only in profits knowingly harms the environment, should we say he did so intentionally? The students answered yes. Yet if the same businessman knowingly helped the environment, they said no. Apparently, intentionality depends not just on an actor's state of mind, but also on the outcome he or she produces.
And also on skill—the ability to carry out one's intention. If you hit a bulls-eye your first time playing darts, did you do it "intentionally"? It turns out that the most common answer is yes if you keep regularly hitting the target and no if you don't. Outcome trumps skill, though, when it comes to determining intentionality. Say a man tries to shoot his aunt, misfires, but is lucky and hits her anyway. Most people will say he killed her intentionally, even though he didn't really have the skill to. It's enough that he wanted to.
Hijackers with experimental drugs, land-despoiling executives, aunt killers—what's not to like about x-phi?
I asked Ernest Sosa, a respected critic of the field, to summarize his objections. The experimentalists, he replied, can't prove that their subjects are actually responding to the philosophical principles at stake. People may be distracted by certain language choices or irrelevant details in the scenarios being posed. In a classic psychology experiment, people chose to save 200 lives rather than take a one-in-three chance at saving 600 lives. Yet if asked instead to choose between sending 400 people to death or taking a two-in-three chance that 600 people would die, they embraced the latter option. The options presented in the two scenarios are identical, of course, just worded differently. Which suggests that the way you tell a story affects what emotions people feel upon hearing it, which in turn affects their decision-making.
Perhaps surprisingly, Sosa's biggest objection to x-phi is that it hasn't gone far enough. The new field has revised philosophers' notions of what people actually think. But it's more important for philosophy to test whether they're right, he argues. Take skepticism, the theory that holds that we can't know anything for sure. Skepticism "relies crucially on the idea that for all we can really tell, life is but a dream," Sosa points out. This in turn depends on our common-sense conception of dreams as hallucinations. But is the dreaming brain really like the hallucinating brain? Why not enlist some neuroscientists to find out, Sosa says, and replace thought experiment with real experiment?
Other scholars argue that the changes wrought by experimental philosophy will in any case be limited. Some elemental principles of philosophy don't depend at all on assumptions about human psychology. And, when they do, philosophers can just replace the answers to a few questions with different ones (moral responsibility doesn't always require free will, for example) and then carry on as usual.
At the same time, certain recent experiments suggest that some philosophical questions will never be re-settled empirically, because the underlying psychology varies too widely among different groups of people. This fear has been voiced for years in philosophical debates on moral relativism, which contemporary philosophers have embraced less enthusiastically than other academics but haven't rejected entirely. And it's becoming increasingly inescapable.
Researchers from the United States and Brazil posed the following hypothetical: "A man goes to the supermarket once a week and buys a dead chicken. But before cooking the chicken, he has sexual intercourse with it. Is that wrong?" People in both countries said it's not OK to eat a sexed-up chicken considerably more often if they hailed from a low socioeconomic background. Cultural differences extend even to basic matters such as the meaning of language. Imagine that Gödel didn't invent Gödel's Theorem. Some guy named Schmidt did. Then to whom do we refer when we continue to use the word "Gödel"? In one experiment, researchers found that Americans tend to say, "the guy who got credit for the theorem," while Hong Kongers say, "the guy who actually came up with it."
Even if philosophers manage to put forth new theories based on answers that are replicated all over the globe, philosophy will never regain its old degree of certainty. What makes x-phi revolutionary, and horrifying to some, is that once philosophy opens up to the methods, and the irreducible uncertainties, of empirical science, its tenets can no longer be articles of faith. Philosophy is no longer something you believe in. It's something you test, and expect to change tomorrow.