This is what philosophers call causal determinism—the idea that, as the Stanford Encyclopedia of Philosophy puts it, “every event is necessitated by antecedent events and conditions together with the laws of nature.” This view is what prompts Gazzaniga to say that “the concept of free will is without meaning.” It is what leads the biologist Jerry Coyne to assert, “No, we couldn’t have had that V8, and Robert Frost couldn’t have taken the other road.” If phenomena like choice blindness suggest that we may not understand our own choices (which is disconcerting enough), determinism suggests that whatever choice we make is the only choice we could have made—and therefore, arguably, it is no choice at all. It’s the disquieting possibility from which so many books on choosing shy away in their closing moments.

While science has yet to prove that the universe is mechanistic, the evidence thus far has rarely been helpful for free will, at least as it is popularly understood. In particular, a series of experiments reaching back to the early eighties have shown (with caveats) that unconscious neural activity in the brain seems to precede our conscious awareness of having made a decision, in some cases by as much as seven seconds. Benjamin Libet was one of the first scientists to study this effect; in a seminal study from 1983, he found that a subject’s conscious intent to make small finger movements came only after certain neural processes had already indicated the movement would occur. That finding has generally been supported by subsequent researchers, including the neuroscientist Itzhak Fried, who was able to predict with roughly 80 percent accuracy which of two buttons a subject would press before the subject reported he or she had consciously decided to do so. More recently, researchers have found that the unconscious activity isn’t limited to small motor movements, but also occurs when volunteers are asked to choose whether to add or subtract a given series of numbers. This allowed the scientists to predict the subjects’ choices “considerably better than you would expect by chance,” as one of them put it. The study, by John-Dylan Haynes and Chun Siong Soon, is called “Predicting Free Choices for Abstract Intentions,” and the unintentionally disturbing title is of a piece with the sense one gets, in reading neuroscientific literature, that the idea of choice may soon be preserved only by defining it out of recognition.