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the new parts of the brain, evolution just hasn't had time to work out the kinks.
    The emotional brain, however, has been exquisitely refined by evolution over the last several hundred million years. Its software code has been subjected to endless tests, so it can make fast decisions based on very little information. Look, for instance, at the mental process involved in hitting a baseball. The numbers make the task look impossible. A typical major-league pitch takes about 0.35 seconds to travel from the hand of the pitcher to home plate. (This is the average interval between human heartbeats.) Unfortunately for the batter, it takes about 0.25 seconds for his muscles to initiate a swing, leaving his brain a paltry one-tenth of a second to make up its mind on whether or not to do so. But even this estimate is too generous. It takes a few milliseconds for the visual information to travel from the retina to the visual cortex, so the batter really has fewer than five milliseconds to perceive the pitch and decide if he should swing. But people can't think this quickly; even under perfect conditions, it takes the brain about twenty milliseconds to respond to a sensory stimulus.
    So how does a major-league baseball player manage to hit a fastball? The answer is that the brain begins collecting information about the pitch long before the ball leaves the pitcher's hand. As soon as the pitcher begins his wind-up, the batter automatically starts to pick up on "anticipatory clues" that help him winnow down the list of possibilities. A torqued wrist suggests a curveball, while an elbow fixed at a right angle means that a fastball is coming, straight over the plate. Two fingers on the seam might indicate a slider, and a ball gripped with the knuckles is a sure sign that a wavering knuckleball is on its way. The batters, of course, aren't consciously studying these signs; they can't tell you why they decided to swing at certain pitches. And yet, they are able to act based on this information. For instance, a study of expert cricket batters demonstrated that the players could accurately predict the speed and location of the ball based solely on a one-second video of the pitcher's wind-up. The well-trained brain knew exactly what details to look for. And then, once it perceived these details, it seamlessly converted them into an accurate set of feelings. For a hitter in the major leagues, a hanging curveball over the center of the plate just
feels
like a better pitch than a slider, low and away.
    We take these automatic talents for granted precisely because they work so well. There's no robot that can hit a baseball or throw a football or ride a bicycle. No computer program can figure out which actor should play a villain or instantly recognize a familiar face. This is why when evolution was building the brain, it didn't bother to replace all of those emotional processes with new operations under explicit, conscious control. If something isn't broken, then natural selection isn't going to fix it. The mind is made out of used parts, engineered by a blind watchmaker. The result is that the uniquely human areas of the mind depend on the primitive mind underneath. The process of thinking requires feeling, for feelings are what let us understand all the information that we can't directly comprehend. Reason without emotion is impotent.
    One of the first scientists to defend this view of decision-making was William James, the great American psychologist. In his seminal 1890 textbook
The Principles of Psychology,
James launched into a critique of the standard "rationalist" account of the human mind. "The facts of the case are really tolerably plain," James wrote. "Man has a far
greater
variety of impulses than any other lower animal." In other words, the Platonic view of decision-making, which idealized man as a purely rational animal defined "by the almost total absence of instincts," was utterly mistaken. James's real insight, however, was that these