An Essay on Free Will

Overview

An Essay on Free Will (1983), by Peter van Inwagen, is one of the most important works in twentieth-century philosophy of free will. It is the book that restored incompatibilism — the thesis that free will and determinism cannot both be true — to respectability in Anglo-American philosophy, after decades in which compatibilism had seemed the default position. Its centerpiece is the Consequence Argument, a formal argument intended to show that if determinism is true, no one can act otherwise than they do, and therefore no one has free will.

The book is a model of analytic philosophical method. It begins by defining its terms with care — what "free will" means, what "determinism" means — and then proceeds by rigorous argument, considering objections with unusual patience and candor. Van Inwagen is famous for the honesty with which he reports the state of his own convictions: he concludes that we cannot both have free will and live in a deterministic world, and that he is therefore "profoundly uncertain" which is true.

The book has a further, striking feature: its famous "Rollback Argument" is not the only famous argument in it. The book also contains an early defense of the thesis that moral responsibility requires free will, and a discussion of the "direct" arguments for incompatibilism — arguments that seek to show that responsibility and determinism conflict even without the detour through the ability to do otherwise.

Core Thesis

The core thesis of An Essay on Free Will is incompatibilism: free will and determinism are incompatible. The argument is the Consequence Argument, which can be stated roughly as follows. If determinism is true, then our acts are the consequences of the laws of nature and events in the remote past. But we have no power over the remote past, and no power over the laws of nature. Therefore we have no power over the consequences of these things — including our present acts. Since having free will requires having power over at least some of one's acts, determinism rules out free will.

Van Inwagen formalizes this argument using a modal operator of "power necessity" and two inference rules. The first rule, sometimes called Rule Alpha, states that if a proposition is necessarily true, then no one has power over it. The second, Rule Beta, states that if no one has power over a proposition p, and no one has power over the conditional "if p, then q," then no one has power over q. Given determinism — the thesis that the conjunction of the past and the laws entails every truth about the future — the argument reaches the conclusion that no one has power over the future, including their own acts.

The book's second thesis is that moral responsibility requires free will in the strong, incompatibilist sense: a person is morally responsible for an act only if they could have done otherwise. Van Inwagen defends this "principle of alternate possibilities" against Harry Frankfurt's influential counterexamples, arguing that the cases Frankfurt uses fail on close inspection, or that they show only that we can be responsible for things we did not choose, not that we can be responsible for things we could not have avoided.

Key Ideas

The Consequence Argument

The Consequence Argument is the book's enduring contribution. Its power lies in its simplicity: determinism says that the past and the laws determine a unique future; we have no control over the past or the laws; so we have no control over the future. If the argument is sound, compatibilism is false, and the free will debate takes on a very different shape.

The argument's formal machinery — the operator "N" ("no one has any choice about whether") and the inference rules Alpha and Beta — was an innovation that reshaped the debate. Subsequent work on free will has largely been organized around the attempt to refute or defend Rule Beta, which came under sustained attack in the 1990s and 2000s. Even philosophers who reject the argument concede that it set the agenda.

The Power to Do Otherwise

The book defends the claim that free will essentially involves the power to do otherwise. Van Inwagen distinguishes several senses of "can" and argues that the sense relevant to free will is the "power to do otherwise" in a strong sense: the power to make the future different from what it in fact will be. This power, he argues, is incompatible with determinism, because under determinism the future is entailed by the past and the laws, over which we have no power.

The defense of alternate possibilities places the book firmly against the Frankfurtian tradition in the theory of responsibility. Van Inwagen's treatment of the Frankfurt cases — the examples designed to show that an agent can be responsible even when unable to do otherwise — is detailed and subtle, and it has provoked a large literature of its own.

Moral Responsibility and Free Will

The book argues that moral responsibility requires free will: you are morally responsible for an action only if you had free will with respect to it. This thesis, sometimes called "the principle of moral responsibility requires alternate possibilities," links the metaphysics of free will to the ethics of responsibility. If determinism is true and incompatibilism is correct, then no one is morally responsible for anything.

Van Inwagen is careful to distinguish the thesis that responsibility requires free will from the thesis that punishment requires it. He is not primarily concerned with the justice of punishment but with the structure of responsibility itself: the idea that a person can be genuinely answerable for an act only if it was up to them whether to perform it.

The "Direct" Arguments

The book contains an early version of what came to be called "direct arguments" for the incompatibility of determinism and responsibility. These arguments aim to show that determinism rules out responsibility without going through the ability to do otherwise: roughly, that if our acts are entailed by the past and the laws, and we have no control over the past and the laws, then we are not morally responsible, even if we could somehow have done otherwise.

The direct arguments were developed further by van Inwagen in later work and by other philosophers, and they remain an active research program. They matter because they promise to refute compatibilism even if the Consequence Argument's Rule Beta should turn out to be invalid — and because they connect the free will debate directly to the ethics of blame and punishment.

Historical Context

An Essay on Free Will was published in 1983, at a turning point in the free will debate. In the 1960s and 1970s, compatibilism had been dominant, buttressed by the work of Harry Frankfurt, who argued that moral responsibility does not require the ability to do otherwise. Van Inwagen's book was the most rigorous statement of the contrary view to appear in a generation, and it changed the terms of the debate.

The book belongs to the tradition of analytic metaphysics that stretches from the logical empiricists through David Lewis and Saul Kripke. Its method — formalization, careful statement of inference rules, exhaustive treatment of objections — is quintessential analytic philosophy. But its conclusions align it with an older tradition: the incompatibilism of philosophers such as Thomas Reid and the libertarian strand in Western thought.

The book's influence was immediate and lasting. It made incompatibilism a live option again, inspired a generation of libertarian philosophers, and forced compatibilists to engage with a much more powerful opponent than they had faced before. Dennett's Elbow Room (1984), published a year later, was in large part a response to the challenge van Inwagen posed.

Legacy & Influence

The legacy of An Essay on Free Will is difficult to overstate. The Consequence Argument is now the standard argument for incompatibilism, taught in every philosophy of free will course, and the debate over Rule Beta produced a substantial literature in the 1990s and 2000s. The book also revived the principle of alternate possibilities and the question of whether responsibility requires free will, both of which remain central topics.

The "direct" arguments have proven equally influential, giving rise to a distinct research program in the philosophy of moral responsibility. And the book's intellectual honesty — its refusal to pretend that the issues are easier than they are — set a standard for the field. Van Inwagen's famous remark that he is "profoundly uncertain" whether determinism is true has become part of the folklore of the discipline.

For the contemporary reader, An Essay on Free Will is best read alongside its major responses: Elbow Room and Freedom Evolves by Dennett, the collected essays in The Oxford Handbook of Free Will, and the recent scientific challenge of Determined by Robert Sapolsky. The surrounding conceptual terrain is mapped in what is free will, what is determinism, and what is the consequence argument.

Sources

• Peter van Inwagen, An Essay on Free Will (Oxford: Clarendon Press, 1983).
• Stanford Encyclopedia of Philosophy, Free Will.
• Stanford Encyclopedia of Philosophy, Arguments for Incompatibilism.
• Stanford Encyclopedia of Philosophy, Compatibilism.
• Stanford Encyclopedia of Philosophy, Moral Responsibility.

Related Topics

• What is free will
• What is determinism
• What is the consequence argument
• Determinism
• Agency
• Elbow Room
• The Oxford Handbook of Free Will