Diderot, the Will, and the Self

For those who think that counterfactual arguments in discussions of free will are an invention of the twentieth century, here is a bit I just came across from Diderot’s D’Alembert's Dream:

What is this free will? … The latest impulse of desire or aversion, the latest result of all that a man has been from the time of his birth to the moment at hand…. You were reduced to a single point; you acted, but did not will. Can we will, all by ourselves? Will is always born of some motive, interior or exterior, of some present impression, or reminiscence of the past, or passion, or future project. That being so I have just one word for you about free will, which is, that the latest of our acts is the necessary effect of a single cause—the self; a very complex cause, but single.

This is an interesting account. On the one hand, Diderot accepts the Hobbesian view of the will: every action is the effect of the latest impulse in a causal chain. At the same time, however, Diderot adds to the Hobbesian doctrine: Instead of simply identifying the will with the last impulse before the action, he tries to avoid the disappearance of the agent; instead, he insists that these impulses are just part of the agent. The acting self is not supplanted by the desires to which it is reduced; rather, the self just is the complex cause consisting of the causal circumstance that causes an action. This doesn’t solve the disappearing agent problem, of course, but redescribes it in a way that makes the real problem more tractable. The question is not whether we can replace the agent by a chain of causes, but rather whether we can reduce the agent to them. These arguments, of course, are still very much around today.

Now here’s the kicker:

Since I acted thus, anyone who acted differently is no longer me; and to assert that at the moment I do or say anything, I can do or say something different is to assert that I am both myself and someone else.

Note the elegance of the argument: having defined the self as a complex deterministic causal circumstance, Diderot simply points out that, since a different action could only have resulted from a different causal circumstance, had I acted differently, I would not have been me. Libertarians who assert that an ability to do otherwise than I really do is a human power are thus committed to something incoherent: the claim that I can be both myself and not myself, both the causal circumstance that caused my action, and at the same time a different causal circumstance.

Libertarians typically deny the assumption that the causal circumstance involved is deterministic. But the argument is, of course, also massively question-begging on another count, since no libertarian (for that matter, almost no compatibilist today) holds that the self is reducible to the entire set of mental and physical states that make it up. There is nothing especially odd about the idea that, although at a particular moment in time I preferred steak to pork chops, I could just as well have preferred pork chops to steak without ceasing to be me. Even if the self is reducible to its character traits, it is not clear that every character trait, or every causal relation between those traits, is constitutive of the entity we call a self. But working out this kind of account, according to which the self, or what is crucial to it, is separated out from more incidental desires, has proven no easy task. Attempts at working out a notion of a “real self” (involving endorsement or wholeheartedness or some such), as well as of a functional self (where the self is identified with some function, such as selecting among motives, or just deliberative processes) have yet to yield anything like an uncontroversial picture.

One difficulty is that, given some commitment to holism, it is unclear how our “wholehearted” states might be demarcated from the “peripheral” or “external” ones. And with this problem in mind, we might also question whether the deliberation involved in establishing a self might somehow be a mental process over and above those peripheral motives—they must, after all, play some role in the overall economy of the self, and so it stands to reason that they, too, will play some role in influencing our deliberation.

Diderot’s challenge, which I have suggested extends not only to libertarianism, but also to most of the compatibilist approaches developed in response to libertarian criticisms, is thus still alive today. Although his positive view might strike many of us as crude, developing an alternative account has not proven easy, and I think his account concisely phrases one of the key problems at the heart of agency theory and free will.