The psychology of teleology

To understand public resistance to evolution, it's helpful to think like a child

| 10 December 2008

Tania LombrozoTania Lombrozo

Charles Darwin should be spinning in his grave: More than 40 percent of American adults still don't believe in evolution. Though Darwin's theory has been uncontroversially accepted among scientists, public resistance remains remarkably forceful. Meanwhile, creationism and intelligent design enjoy widespread public support.

Why do many people find a theory so persuasive to others so hard to accept? Berkeley psychologist Tania Lombrozo, who is interested in why people find certain kinds of explanations more or less compelling than others, may have insight into at least part of the answer. Her research suggests that some theories, like evolution, may be difficult to accept because they are at odds with a human default for understanding the world in terms of design.

Lombrozo was motivated by the observation that young children often explain the existence of objects and phenomena with reference to their function, a kind of reasoning termed teleological. Ask a three-year old why it rains, for example, and you are likely to hear something like "so that plants have water to grow." Likewise, lions exist "for going to the zoo," and mountains "are for climbing." This tendency of children to infer design suggests an explanatory default: In the absence of competing knowledge, the best explanation for an object with a plausible function is that it was designed to fulfill that function.

Unlike children, most educated adults know that clouds form because water condenses, and that mountains exist because of plate tectonics. However, Lombrozo was interested in whether adults would fall back on teleological reasoning in the absence of background knowledge. To address this question, she and her colleagues Deborah Kelemen and Deborah Zaitchik examined a group of adults whose background beliefs were compromised, but who had otherwise developed normally: Alzheimer's patients.

"Alzheimer's patients have some characteristics of adults and some characteristics of children," says Lombrozo. "Like adults, they have undergone normal development and have presumably gotten rid of any reasoning strategies associated only with children. But like pre-school children, they might not have access to the kinds of rich causal beliefs that adults typically have access to."

In her study, subjects were asked to identify the most appropriate answers to a series of "why" questions. For example, for the question "Why does the earth have trees?" they could choose between "because they grow from tree seeds," or "so that animals can have shade." Lombrozo found that like young children, Alzheimer's patients were much more likely than age-matched control subjects to prefer teleological explanations, picking the teleological choice about twice as often as their healthy counterparts.

"The results support the idea that adults and children have the same sorts of cognitive mechanisms at work, and that adults are just overriding the explanatory default with background knowledge," says Lombrozo. They also fit in with findings from other studies that show more frequent use of teleological explanations in less educated adults, and in educated adults making speeded judgments.

Collectively, says Lombrozo, these results may help explain why intelligent design and creationism — teleological arguments that suggest we exist in our current form because we were designed to do so — continue to be so pervasive in today's society. "Many people find it difficult to think that we would be the result of a process that didn't involve design. As a result, intelligent design seems like a much more compelling explanation than evolution. Interestingly, even among those who do accept evolution, many misunderstand it, reinterpreting it as a goal-directed process that occurs at the level of individuals rather than populations."

Why might humans have evolved this kind of a reasoning strategy? Lombrozo has several ideas. "One possibility is that if you look at our evolutionary past or at our experiences growing up, one of the things we did most often was explaining human behavior. And human behavior is generally goal-directed — it does involve intentions and functions. We may be taking the mode of explanation that we're best at and then applying it to other domains," she says. "Another possibility is that it's more effective. We're going to learn more about the world if we go around assuming that things have functions and then sometimes discovering we were wrong, rather than the reverse."

Lombrozo points out that, most of the time, functional explanations don't do a lot of harm. In fact, they can sometimes help people understand concepts that might otherwise be too difficult. In chemistry, for example, it can be helpful to think about the electron wanting to go to where it's positive, or, when learning about evolution, that the moth doesn't want to be visible to its predator. On the other hand, says Lombrozo, systematically catering to what people find satisfying can be bad for their appreciation of science.

"Education is most successful when it gets people to undergo something like a theoretical change," she says. Recognizing what kinds of assumptions people come into the classroom with will help in figuring out how to best accomplish this."

Hania Köver, a graduate student in the Helen Wills Neuroscience Institute, wrote this article for the Fall 2008 issue of Berkeley Science Review, published each semester by student volunteers. For information, including archived articles from past issues, visit