Half-Cups Runneth Over

To the Editors:

In a recent book, Determined: A Science of Life Without Free Will (2023), I argue that contemporary science shows that free will is a myth (along with the passing opinion that the world would become more humane if that myth were jettisoned).

In her review of the book [“Turtles All the Way Up,” NYR, February 13], Jessica Riskin strongly rejects the idea that science informs the free will debate. She bases this on two issues that seem logically and factually suspect:

1. The accretion of scientific knowledge

Crucially, in evaluating what science says about free will, no singular scientific discipline precludes its possibility—no gene(s), neurotransmitter(s), hormone(s), early developmental epigenetic effect(s), and so on, accomplishes this. Collectively, however, they certainly do.

Riskin rejects the notion that multiple scientific disciplines generate insights greater than the sum of each alone. Beginning with a quote from my book, she writes:

“Yeah, no single result or scientific discipline” demonstrates it: “Put all the scientific results together, from all the relevant scientific disciplines, and there’s no room for free will.” Now, is that scientific? To claim that lots of failures to prove something add up to a definitive proof?

Well, yeah, actually, that is scientific. Consider:

Person A: Cups can hold water.

Person B: No they don’t. If you pour water into that half-cup, will it hold water?

Person A: Nope.

Person B: And if you pour water into the other half-cup, will it hold water?

Person A: Nah. But if you glue the two halves together properly, you have a cup that holds water.

Person B: Now is that scientific? To claim that lots of failures to prove something add up to a definitive proof?

In other words, neither half-of-a-glass-ologists nor super-glue-ists can prove that glasses hold water, but you can prove that when combining knowledge from multiple scientific disciplines. That’s how science works.

2. Science and philosophy playing musical chairs

Near the end of her review, Riskin waxes ex cathedra that “science can’t prove there’s no free will because the question of free will is not a scientific question but a philosophical one.”

Consider the following:

A scholar rises one morning to finish some important writing. Unfortunately, things go poorly—her mind meanders on tangents, thoughts fail to coalesce, words elude her. She is immensely frustrated with herself and her lack of focus. She then discovers that, just before starting work, she accidentally made decaf rather than regular coffee. The question of free will is most definitely a scientific question.

The same is shown when a person loathes himself as self-indulgent and unmotivated because of his obesity and poor reading skills, only to discover that he has a gene variant that blunts his hypothalamus’s sensitivity to food satiety signals, or the cortical developmental disorder we term dyslexia. Likewise when a kid raised amid love, security, and well-planned challenges to hone her moral compass turns out to excel at gratification postponement. Or consider the sizable percentage of death row prisoners with histories of traumatic brain injury to their frontal cortex. The question of free will is indeed a scientific question—we are the sum of our biology, which we could not control, and its interaction with environment, which we also could not control.

To agree with Riskin on one point, however, scientists should be shown the door and philosophers ushered in when considering what it means that we lack free will. Where do we find purpose? Why judge our worst and best moments if they are mechanistic? Does it matter if we love and are loved? At that point, rather than consulting someone who obsesses over how caffeine focuses us by blocking adenosine receptors in the basal forebrain, philosophers should hold sway.

Robert Sapolsky
John A. and Cynthia Fry Gunn Professor of Biological Sciences
Stanford University
Stanford, California

Jessica Riskin replies:

Two half-cups glued together might hold water, but Robert Sapolsky’s argument doesn’t. Science works by accretion only if the layers are relevant to the question at hand and can be added together to indicate an answer. The myriad things that influence human behavior, such as caffeine, genetic diseases, or a happy childhood, constitute evidence that people are affected by many different kinds of things, not that these things determine their behavior. For one thing, there’s an important difference between being affected by something and being controlled by it. And for another, these disparate factors don’t add up to any overall “sum.” Sapolsky mentions obesity and dyslexia, for instance. Some studies have shown a relatively low association between variations in DNA and variations in these conditions. In each case, the association itself varies greatly according to environmental factors. No competent statistician would add the genetic and environmental factors, because the interactions among them make such an addition invalid. To add them assumes they must be independent factors, but they aren’t: they interact with one another.

In short, you can’t sum up everything you can list; and if you want to prove something, your evidence has to be appropriate to the thing you’re proving. You can’t add shoes and ships and sealing wax to prove that pigs have wings.