I'm Sorry, Dave, I'm Afraid I Can't Make a U-Turn
Should we be worried that our cars are controlled by software?
Also in Slate, Tom Vanderbilt explains why bad drivers are more dangerous than bum Toyotas.
Software is also inevitably buggy. In very complex systems, engineers regard errors as inevitable. At Microsoft, an OS is considered ready for sale when engineers determine it has fewer than 500 known bugs. And those are just the bugs we know about. Software is hard to test, and errors are sometimes impossible to find in advance. Computers can do so many things at the same time—and so many different things in response to various inputs—that we usually have no idea what they'll do in a given real-world situation. Toyota has hired an independent engineering firm to examine the electronic throttle in its cars. But in the same way that it's often impossible to reproduce the combination of errors that just crashed your PC, these analysts won't be able to go through every situation that might cause the throttle to fail on the road. That's just the price of adding software to cars. Computers make vehicles more complex, and uncertainty is an inevitable cost of complexity. As Donald Rumsfeld might say, you get a lot more unknown unknowns.
But are we human beings much better? We fail in certain predictable, repeatable, and easily preventable ways. We drive too fast or too slowly for certain road conditions. We drive while distracted, intoxicated, or sleepy. We let people drive when they're too young and too old. Our sensory perception is limited—we have blind spots, we can't process simultaneous stimuli, and we can't accurately judge changing road conditions. We're also given to irrationality, letting our emotions take over while we're driving a dangerous machine.
There have been lots of studies looking into the causes of traffic accidents. They all come to the same conclusion—the overwhelming reason we get in crashes is driver error. The best thing about the computerization of cars, then, is precisely the thing we find most terrifying: Software is beginning to override human control. We are the most dangerous parts of the cars we drive. The less driving people do, the fewer people will die on the roads.
Software is already starting to step in for human beings who fail on the road. Many cars now come equipped with autonomous cruise control, systems that use laser or radar to determine if your car is getting too close to other vehicles and automatically slow you down if you are. We've also got electronic stability control—a computer constantly monitors your wheels to determine if you're skidding and steers you back on course if necessary.
Is it scary that we're putting in systems that let computers override human judgment? Only if you believe that human judgment is infallible. I don't. Sure, it's unnerving that a computer is now running my car. But I'm sure glad it's running yours.
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Farhad Manjoo is Slate's technology columnist and the author of True Enough: Learning To Live in a Post-Fact Society. You can email him at email@example.com and follow him on Twitter.
Photograph of a Toyota Prius hybrid by Kazuhiro Nogi/AFP/Getty Images.