Therapy for Psychology and Philosophy: The Final Session

If there’s one particular sore point in the relationship of psychology and philosophy, one nettlesome issue that annoys both parties, it’s probably evolutionary psychology. Evolutionary psychologists attempt to apply Darwinian explanations to human behavior. Some have theorized, for example, that the innate fear many people have of spiders is a result of natural selection. Those early humans who avoided spiders and their sometimes lethal bites were supposedly more likely to survive and pass their genes on to subsequent generations.

Philosophical skepticism about such theories basically comes in two types: questions of verifiability and questions of falsifiability. Scientists generally verify their hypotheses by predicting outcomes, controlling for as many variables as possible, and then testing to see if the predicted outcomes actually occur. This sort of prediction and testing obviously cannot be done on evolutionary psychological hypotheses. They are, by their very nature, hypotheses about the past, and in the past the variables were not controlled for. Evolutionary explanations of behavior can therefore never escape the category of “untested hypotheses.”

As the twentieth-century philosopher Karl Popper pointed out, scientific hypotheses, in addition to needing to be verifiable, also need to be falsifiable. That is, there must be some conceivable set of facts that would disprove the hypothesis. If we can explain away the fact that there are some people who are not afraid of spiders by saying they are genetic outliers, then our theory really doesn’t explain very much. If we then adapt the theory to say that natural selection at least explains the fear of those people who are afraid of spiders, then we would have to ask, “What conceivable evidence could there be that natural selection did not determine these people’s fear of spiders?” Because it’s impossible to imagine what such evidence would look like, most philosophers would say the evolutionary explanation of fear of spiders is a hollow theory.

We’ve been speaking of particular theories—such as the origin of the fear of spiders—that an evolutionary psychologist might propose. If we look at the general theory of evolutionary psychology itself, philosophers might say that the theory is too elastic to be helpful. As chemist Philip Skell says, “Darwinian explanations [of behavioral phenomena] are often too supple: Natural selection makes humans self-centered and aggressive—except when it makes them altruistic and peaceable. Or natural selection produces virile men who eagerly spread their seed—except when it prefers men who are faithful protectors and providers.” This is another way of saying that the general theory of evolutionary psychology isn’t falsifiable. That is, it would be impossible to think of a human trait that would not give some natural advantage to our ancestors.

There is one further philosophical challenge to the latest trend in evolutionary psychology, attempting to explain the development of morality. Evolutionary psychologists, have weighed in, for example, on the so-called trolley problem. Most people would be willing to throw a switch that would divert a runaway trolley onto a siding, if by so doing they would save the lives of five people on the main track at the cost of one person on the siding. Most people, however, would not throw a heavyset man in the path of the trolley in order to save the five. Some evolutionary psychologists have theorized that this is because we have a greater emotional reaction to the literal killing of the fat man than we do to simply “allowing” a person to be killed by the throwing of the switch. Further, they say, this is because our distant ancestors experienced literal killing and being killed, and those who adapted to the threat of being killed were the ones more likely to survive and pass on their DNA. Some psychologists want to say that this genetically hard-wired response is the whole sum and substance of what we mean when we say it’s “wrong” to kill the fat man.

The early twentieth-century philosopher, G.E. Moore, called this reduction of morality to psychology the “naturalistic fallacy.” He said the concept of “good” is irreducible. We can always ask if our hard-wired response is good. People will not think we are asking if our hard-wired response is our hard-wired response; that’s because they know that “good” means something else.

And so, our couples therapy for psychology and philosophy comes to a close. The stickiest issue is evolutionary psychology. They’re just going to have to work it out.