It's shortly before dawn, and the handful of early-morning commuters on the fog-shrouded suburban highway don't see the deer meandering across the road. Luckily, though, their cars see the animal. In an instant, the closest vehicle quickly applies its brakes and turns its wheels, steering around an otherwise imminent collision. It then sends warning messages to oncoming traffic, as well as to the vehicles behind it, which dutifully apply their brakes and slow to a near-crawl as the deer passes.

None of the drivers, however, is disturbed by the near miss. A few are too engaged in their morning newspapers; a couple more are snoozing for a few more minutes before arriving at the office. All are blissfully unaware of the incident because they, the "drivers," aren't driving; they're being chauffeured by their self-navigating vehicles.

Sound impossible? Many automotive experts don't think so. The technological pieces needed for a self-navigating vehicle are already falling into place, they say. But it will take at least two to three decades before those pieces will be assembled into a car that drives itself.

You say that self-deceived people are often mentally healthier than those who are honest with themselves.

Yes, lying to oneself promotes psychological well-being. Research shows that depressed people deceive themselves less than those who are mentally healthy. Frankly, if we did not deceive ourselves, I think we would go mad from distress. For example, the simple fact that we're all going to die, that there are various people in the world out to get us, that a good deal of the world lives in unrelenting misery and hunger-it's all enough to drive everyone bonkers. Unless we are capable of shielding ourselves from that, we would be constantly disturbed. It's why we worry more about missing our favorite TV show than about a dirty bomb going off in a terrorist attack.

Also, self-deception relieves us from a sense that we're constantly living in contradiction. We each have a set of values that we constantly violate. When you're aware of transgressing one of those values that you hold dear, you tend to feel bad about yourself. In deceiving ourselves, we relieve ourselves of that burden, making life a lot easier and lot more pleasant for ourselves. It's quite wonderful.

Finally, if we convince ourselves we're not really lying, we can lie far more effectively than might otherwise be the case. All of our social lies, like the fake smile, involve the manipulation of how others see us. Our lives are saturated with pretense and dishonesty. Although we claim to value truth above all else, we are also at least dimly aware that there is something antisocial about too much honesty.

So should we value lying more than telling the truth, especially since you said that good liars have an advantage in life?

When I'm talking about advantage, I'm talking about what gives an individual organism success. But all sorts of things can give individual success. Killing one's rivals is an example, but just because it gives you an advantage doesn't morally justify it. Put it this way: If one thinks that individual advantage is the ultimate value in life, it would follow that one should work at becoming a very good, calculating liar. But encouraging lying to one's individual advantage will always receive social disapproval, because if you are taught to lie better, that's against everyone's interest. Just as it might be advantageous for each of us to lie, it's disadvantageous for each of us to be lied to. For lying to be advantageous, society has to place an emphasis on honesty. Unless we have a sense that there's truthfulness enough of the time, lying ceases to function. That's illustrated in the old story about the boy who cried wolf. If we get a situation where we're all cold-bloodedly out to lie to each other, we will lose trust in each other, lying will stop working, and the world would collapse under the weight of too much lying.