Robert Sapolsky and Kevin Mitchell Diverge on Free Will

Robert Sapolsky (2023) and Kevin Mitchell (2023) are both biologists who have written books that come to opposite conclusions about the existence of free will. Sapolsky's book Determined argues that our best scientific evidence points to the absence of free will, while Mitchell's book Free Agents claims that our best scientific evidence establishes the existence of free will. In this post, I explain how two competent scientists, looking at the same evidence, come to opposite conclusions about free will, and how this disagreement might hinge on different definitions of free will.

Points of Agreement Between Sapolsky and Mitchell

Sapolsky and Mitchell both follow the widely accepted view about the evolution of the brain and nervous system. Both note that the behavior of the earliest organisms was reflexive, automatically responding in set ways to events in the environment. Over evolutionary time, the brain developed the capacity to contemplate behavioral options before responding to environmental events, adding flexibility to behavior.

Sapolsky and Mitchell also agree that individuals differ in the amount of control they have over their impulses. Both note that the frontal cortex is largely responsible for self-regulation. The frontal cortex does not fully mature until the mid-20s and shows a decline in old age, which means that younger and older people can have more problems with self-regulation than people between the ages of 30 and 70. Also, stress, traumas, tumors, parasites, addictions, and other diseases can adversely affect frontal cortex functioning, lowering people's ability to self-regulate and make optimal choices. For this reason, Kevin Mitchell says that free will is not an either-or issue, but, rather, a matter of degree. Sapolsky, noting that people cannot choose how well their frontal cortex regulates behavior, refuses to call differences in self-regulation differences in free will.

Sapolsky and Mitchell also agree that it is impossible to be free from all past and present influences on behavior. For Sapolsky, the impossibility of escaping all influences on behavior is his reason for denying the existence of free will. Mitchell rejects the traditional definition of freedom in philosophy as "the ability to act absolutely free from any prior causes whatsoever" (p. 278). He continues, (p. 279), "To be free of such constraints would be to act randomly, pointlessly, on a whim, for no reason."

Mitchell's Argument for Free Will

Mitchell argues that free will—the capacity for conscious, rational control of one's behavior—is a more evolved form of two characteristics of every living organism: agency and autonomy.

"You are the type of thing [unlike rocks, atoms, or planets] that can take action, that can make decisions, that can be a causal force in the world: you are an agent. And humans are not unique in this capacity. All living things have some degree of agency. That is their defining characteristic, what sets them apart from the mostly lifeless, passive universe. Living beings are autonomous entities, imbued with purpose and able to act on their own terms, not yoked to every cause in their environment but causes in their own right" (Mitchell, 2023, p. 19).

According to Mitchell, all living beings have autonomy, a separateness from the surrounding environment. The membrane of the first life forms brought hydrogen ions and organic molecules into the organism, allowing it to generate its own energy and create increasingly complex organic molecules. This gave them a degree of autonomy or self-sufficiency. In Mitchell's words, "This kind of proto-life would have a degree of independence—of freedom—from the environment" (p. 33).

Mitchell's outline of evolutionary steps (Figure 1.3 on page 20) charts organisms' increasing freedom to persist and flourish. The increasing degrees of agency, autonomy, and freedom in each stage of evolution reached their peak in the human brain, which possesses considerable independence from the immediate situation.

As a human being, you can close your eyes and imagine yourself engaging in different activities, estimating the probabilities of different consequences from the activities, weighing the costs and benefits, and deciding what course of action to take. By "free will" Mitchell means this capacity to press the pause button on life, contemplating possibilities instead of reacting immediately and automatically to every immediate situation like most other animals.

Mitchell appeals to your personal experience of free will to demonstrate that it exists. You can observe yourself exercising free will every time you make conscious choices in the way Mitchell describes, and this is Mitchell's prima facie evidence for the existence of free will.

Sapolsky's Argument Against Free Will

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Sapolsky (2023) argues that people lack free will because previous events over which the person had no control collectively determine every conscious choice. In chapter 3 of Determined, Sapolsky agrees with Mitchell that many choices are preceded by conscious intent. But where did that intent come from? From current hormone and blood sugar levels to cultural values instilled by parents through reward and punishment, to drugs, alcohol, and stress hormones in the mother's body during pregnancy, to inherited genetic influences, to ecological features that shaped human evolution, all of these events over which we have no control precede any conscious intent; therefore, we lack free will.

Sapolsky also agrees with Mitchell that we feel that our choices are free and that we can give reasons for our actions, but we can also be mistaken and self-deceived about the real reasons for our actions. Michael Gazzaniga (1985) has described research demonstrating that the right cerebral hemisphere of the brain can initiate behaviors that are incorrectly explained by the language centers in the left cerebral hemisphere. Creating reasonable but false explanations is called confabulation.

Similarly, Nisbett and Wilson (1977) conducted a series of studies in which they manipulated factors that demonstrably influenced participants' choices and then asked participants to give reasons for their choices after introspecting on their choice process. Oblivious to the manipulated influences on their choices, participants in the study confabulated reasons for their behavior.

Although we are sometimes aware of our conscious reasons for doing something, we cannot be aware of the unconscious reasons for our behavior, so we can never tell how much these unknown reasons restrict our freedom. Because we cannot know or control unconscious influences on our behavior, Sapolsky says our will is never free.

Semantics and Implications

Sapolsky's and Mitchell's disagreement about the existence of free will might be a matter of semantics, of how "free will" is defined. Both agree that people differ in their ability to make optimal choices and to achieve their goals. Where Mitchell calls this degrees of free will, Sapolsky would probably prefer to talk about individual differences in competencies and behavioral traits that underlie achievement, such as self-control, clarity about goals, creativity, intelligence, and so forth. These competencies, he would say, cannot be willed into existence; rather, they are all givens, determined by a vast number of prior events over which the person has no control.

But just because disagreements about free will might boil down to different definitions of free will, this doesn't mean that the arguments are just semantics. Different positions on free will have different and profound implications on practical matters such as moral and criminal responsibility, blaming and praising people, and appropriate consequences for misbehavior. I will explore those implications in a future blog post.