On Monkeys, Taoism, and Behavioral Economics

Zhuangzi, apparently talking to a frog. Public domain.

The Chinese language contains many phrases known as chengyu (成語), literally “fixed expressions,” what in English we’d call cliches but which are an indispensable part of Chinese.

One fixed expression goes, “three in the morning, four in the evening” (朝三暮四). Today the expression is used to describe someone who is mercurial, hot and cold, inconstant. But that’s not what it originally meant. ​

Many fixed expressions have fun origin stories. This one goes back to ancient Taoist philosophy. In Zhuangzi, a foundational text of Taoism named after its author and published in the third century B.C., there’s a cute fable in “A Theory on the Equality of All Things” (莊子‧齊物論) about a man who raised monkeys and could talk to them. The man came to the monkeys and said, “How about I feed you three fruits each in the morning, and four in the evening?” The monkeys protested that this was not enough food. The man nodded and went away. A little while later he returned and made another proposition: “How about I feed you four fruits each in the morning, and three in the evening?” The monkeys now cheered and accepted the proposal.

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Capuchin monkeys. Photo courtesy of Frans de Waal. Powell K: Economy of the Mind. PLoS Biol 1/3/2003: e77.

Philosophically, Zhuangzi was illustrating the irrationality of man, the way people worry about this and that when in the end it’s all the same. Presumably he could not have known that 2,300 years later economists would conduct an experiment that was basically a version of this fable.

But first of all I need to point out that the monkeys in “A Theory on the Equality of All Things” were NOT being irrational. As anyone who studied economics knows, there is such as a thing as the time value of money. A dollar today is better than a dollar tomorrow. This is why lenders charge interests. If I lend you a dollar today, but you won’t repay me until a year from now, then you need to repay me more than a dollar, because in that year I am not able to use or invest that dollar, and that’s a loss of value. So when the monkeys cheered at having four fruits in the morning and three in the evening, they were cheering the extra time value gained by getting the extra fruit earlier in the day.​ Zhuangzi, not having read the works of Adam Smith and Paul Samuelson, presumably did not understand this.

Economists got rid of the time value problem when they adapted this fable as an experiment, recounted in Super Freakonomics, the 2009 book by Steven Levitt and Stephen Dubner. First, economists taught a group of capuchin monkeys the value of money by giving them coins and then training them to understand that when they gave coins back to the researchers, they received grapes. Then:

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[The researchers] set up two gambling games. In the first, a capuchin was shown one grape and, depending on a coin flip, either got only that grape or won a bonus grape as well. In the second game, the capuchin started out seeing two grapes, but if the coin flip went against him, the researchers took away one grape and the monkey got only one.
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In both cases, the monkey got the same number of grapes on average. But the first gamble was framed as a potential gain while the second was framed as a potential loss....

Once the monkeys figured out that the two-grape researcher sometimes withheld the second grape and that the one-grape researcher sometimes added a bonus grape, the monkeys strongly preferred the one-grape researcher. A rational monkey wouldn’t have cared, but these irrational monkeys suffered from what psychologists call “loss aversion.” They behaved as if the pain rom losing a grape was greater than the pleasure from gaining one.

As it turns out, even if Zhuangzi didn’t understand the time value of money, his point about the irrationality of man still holds. “The fact is that similar experiments with human beings — day traders, for instance — had found that people make the same kind of irrational decisions at a nearly identical rate.”