Are People Rational?

I have recently been reading "Kluge: The Haphazard Evolution of the Human Mind ," by psychology Professor Gary Marcus of NYU. It argues persuasively that our minds, far from being perfect evolutionarily fine-tuned instruments of clear and incisive thought, are more like contraptions assembled higgledy-piggledy out of pieces left over from our earliest ancestors, with whatever adjustments from time to time make the thing work. The result is a mind that, though powerful, is easily confused and cannot be counted on to be rational.

As with the rest of the growing bandwagon of "behavioral economics" studies, this raises important questions about "economic man" ("econs.") Kluge is full of clever experiments showing that people routinely draw conclusions and make decisions that are not expected of econs. For example, most people, given a set of alternatives, often make selections that are clearly more costly or less effective than others equally available to them. Similarly, their answers systematically change when completely unrelated information is also given them at the same time. Marcus (and others) therefore conclude that people often, and predictably, do not behave rationally (that is, like econs) and that their behavior cannot be assumed to represent their most beneficial choice.

But Maybe Not. This is a questionable interpretation, since it omits at least two major possibilities; first, the effect of people's environment on their mental behavior, and second (by far the more important of the two), the effect on their thinking itself of differences in the consequences of that thinking.

Through ongoing evolutionary adaptation, the human brain has developed quite remarkable problem-working abilities. But there is a great difference between work intended to address an imminent and consequential problem (That's a tiger!) and simple play (I'm bored.) We know that when minds are not occupied otherwise, thoughts can run wild. ("The devil makes work for idle hands.") Dreams are probably minds at play, or at least in neutral. Even motors may change speed without a direct command, and computer memories may become momentarily active. To deal with tigers, we can't afford to have our minds completely at rest; they must be able to react fast. Keeping the brain ready for action is an evolutionary imperative.

The experiments described in Kluge may not, therefore, show much about the operation of a mind focused on a significant task. George McClellan, a pioneering psychologist concerned with human motivation, used to demonstrate the power of this imperative in the classroom. He would draw a long chalk line on the floor, set a container at one end of the line, tell the students that they could stand "anywhere on the line", and give them a ball. The task was simply to get the ball into the basket. The results are always the same: where people stand along the line fits a normal distribution, with almost no one standing next to the container, and the mean position at a significant distance from it. Even though success could be guaranteed by standing closer, most people elect to make the task "worthwhile" by making it harder.

In short, people make many surprising decisions but they may be more rational than the behavioral economists think. Their view of rationality is more or less limited to economic costs and benefits, whereas in reality, there are many other entirely rational reasons -- to people, but not to econs -- among which may be many tradeoffs. It would therefore be wise not to limit arbitrarily our view of rationality but to stretch it to more accurately fit people's hopes and concerns.