---
title: Free Will and Determinism
sort: 130
section-id: metaphysics
description: Hard determinism, libertarianism, compatibilism, and Frankfurt cases.
language: en
---

# Free Will and Determinism

The free will debate is among philosophy's most enduring and personally consequential. It asks whether, in a deterministic universe, human beings can be genuinely free — free in a way that makes praise, blame, punishment, and moral responsibility appropriate. The question matters not just theoretically but practically: legal systems, personal relationships, and our self-understanding all presuppose that people can be held responsible for their actions.

## The Incompatibilist Intuition

The *basic argument* for incompatibilism runs roughly as follows ^[Van Inwagen, P., *An Essay on Free Will*, Oxford UP, 1983, pp.56-105]:

1. Determinism is true: every event, including every human action, is causally necessitated by prior events in conjunction with the laws of nature.
2. If determinism is true, then no one ever could have acted otherwise than they did.
3. Moral responsibility requires the ability to have acted otherwise.
4. Therefore, if determinism is true, no one is morally responsible for anything.

This argument has considerable intuitive force. If my action was causally determined by events that happened before I was born, in what sense was it *my* choice? If the complete causal history of the universe made my decision inevitable, how am I the author of it in any meaningful sense?

## Hard Determinism

*Hard determinists* accept incompatibilism and accept determinism, concluding that free will does not exist and moral responsibility must be radically revised or abandoned.

Derk Pereboom has argued for *hard incompatibilism* with increasing sophistication ^[Pereboom, D., *Living Without Free Will*, Cambridge UP, 2001]. He accepts that moral luck undermines responsibility, that determinism (or indeterminism, for different reasons) threatens desert-based punishment, but argues that a meaningful life can be constructed without the reactive attitudes (blame, indignation, gratitude) that presuppose responsibility.

The practical implications are significant: criminal punishment on retributive grounds is unjustified; therapeutic and quarantine-based reasons for incapacitation remain. Reactive attitudes would be gradually replaced by more forward-looking responses.

## Libertarianism About Free Will

*Libertarians* (in the metaphysical sense, entirely distinct from political libertarianism) accept incompatibilism but reject determinism, maintaining that free will requires — and we have — a form of causation that is not deterministic.

Agent causation: Roderick Chisholm argued that free action requires *agent causation* — a primitive, irreducible capacity of persons as agents to initiate causal chains, not wholly determined by prior events ^[Chisholm, R., "Human Freedom and the Self", in *Free Will*, ed. Watson, Oxford UP, 1982].

The *undetermined choice*: Robert Kane developed an account on which free will-exercising decisions occur at moments of *self-forming actions* — quantum-indeterminate moments of genuine undeterminedness, where the agent's character and reasons could have produced either outcome ^[Kane, R., *The Significance of Free Will*, Oxford UP, 1996].

Libertarianism faces the *luck objection*: if my action was undetermined, then it seems random rather than free. An undetermined choice is one that even I could not have predicted from my own character and reasons — which seems to undermine rather than secure my authorship of the action.

## Compatibilism

*Compatibilists* reject the third premise of the basic argument. Moral responsibility, they argue, does not require the ability to have done otherwise in the libertarian sense. What matters is whether the action was performed for the right kinds of reasons, whether the agent was responsive to reasons, whether the action was voluntary in the relevant sense.

**Classical compatibilism:** Hume, and following him most analytic philosophers of the twentieth century, held that freedom is simply the ability to act in accordance with one's own desires, without external compulsion ^[Hume, D., *Enquiry*, §8]. Coercion, addiction, and phobia compromise freedom; determinism does not.

**Hierarchical compatibilism:** Harry Frankfurt proposed that what matters for freedom is the *structure* of the agent's motivations ^[Frankfurt, H., "Freedom of the Will and the Concept of a Person", *Journal of Philosophy* 68, 1971, pp.5-20]. We have first-order desires (I want to smoke) and second-order desires (I want to want to smoke, or I want not to want to smoke). A free agent is one whose first-order desires align with their second-order volitions — who acts from desires they endorse. This hierarchical structure distinguishes the wanton (who acts on whatever desire is strongest) from the autonomous agent.

**Reasons-responsiveness:** John Martin Fischer and Mark Ravizza developed the view that free agency requires mechanisms that are *reasons-responsive* — mechanisms that would have produced different choices had there been different reasons ^[Fischer, J.M. and Ravizza, M., *Responsibility and Control*, Cambridge UP, 1998]. You are responsible for actions that flow from your own reasons-responsive mechanisms.

## Frankfurt Cases

Harry Frankfurt's most influential contribution is the *Frankfurt case*, designed to challenge the *Principle of Alternative Possibilities* (PAP): a person is morally responsible for their action only if they could have acted otherwise.

The structure: Black wants Jones to perform some action. Black has installed a mechanism in Jones's brain that will, if Jones shows any sign of not performing the action, intervene and ensure Jones performs it. In fact, Jones performs the action on his own, and the mechanism never activates. Jones could not have done otherwise (the mechanism would have prevented it). But, Frankfurt argues, Jones is clearly morally responsible ^[Frankfurt, H., "Alternate Possibilities and Moral Responsibility", *Journal of Philosophy* 66, 1969, pp.829-839].

If Frankfurt cases are sound, PAP is false, and the basic incompatibilist argument loses its third premise. The literature on Frankfurt cases is enormous: compatibilists have used them to argue that alternative possibilities are not required for responsibility; incompatibilists have argued that Frankfurt cases either fail to establish genuine alternative possibilities being closed off, or leave open a "flicker of freedom" ^[Kane, R., "Two Kinds of Incompatibilism", *Philosophy and Phenomenological Research* 50, 1989].

## Strawson's Reactive Attitudes

P.F. Strawson argued that the debate misses what is most important about responsibility: our *reactive attitudes* ^[Strawson, P.F., "Freedom and Resentment", *Proceedings of the British Academy* 48, 1962]. Resentment, gratitude, indignation, and love are the appropriate responses to the quality of an agent's will toward us. These attitudes constitute — rather than presuppose — our moral practices. The question of whether determinism is true is largely beside the point; what matters is whether we are the kinds of creatures to whom it is appropriate to hold reactive attitudes, and we clearly are.

Strawson's insight is that moral responsibility is essentially an interpersonal, practice-constituted phenomenon, not primarily a metaphysical one.

The free will debate has not converged. Compatibilism is the most widely held view among professional philosophers, but libertarian and hard incompatibilist positions retain significant defenders. The question of what freedom requires — and whether we have it — remains genuinely open.
