The oldest tension in philosophy: from Chrysippus' compatibilism and Augustine's grace to Kant's autonomy, Sartre's radical freedom, and van Inwagen's consequence argument.
Are our choices genuinely up to us, or is everything we do fixed in advance — and could freedom and determinism both be true?
Does it lie within our power to act otherwise than we do? The question links physics, theology, and ethics: if every event is caused by prior events, or foreknown by God, or fixed by our own character, then in what sense are we the authors of our deeds and fit to be praised or blamed? Ancient Stoics and many moderns are 'compatibilists', holding that freedom just means acting from one's own desires without external compulsion, so determinism poses no threat. Libertarians insist genuine freedom requires that the future be truly open and that we could have done otherwise; hard determinists conclude that, since it is not open, free will is an illusion. Between them run subtler positions — Kant locating freedom outside the causal order, Frankfurt grounding it in identifying with one's own desires — that keep the debate very much alive. This is not merely academic: our whole practice of responsibility hangs on the answer.
Ancient Greek (Peripatetic)
Aristotle has no term for 'free will', but he analyses voluntary action, choice, and what is 'up to us' (eph' hēmin). An act is voluntary when its origin is in the agent, who knows the circumstances and is not compelled from outside, and we are responsible for the character our repeated choices form. Praise and blame apply precisely because virtuous and vicious action lie within our power.
Nicomachean Ethics, Book III, chs. 1–5.
Stoicism
Chrysippus is the great ancient compatibilist: everything happens by fate, yet some things are 'in our power' because they depend on our own assent. His cylinder analogy distinguishes the external push that starts the cylinder rolling from its own rounded shape, which determines how it rolls — so our actions are fated through, not against, our own nature and character. Responsibility survives determinism because the proximate cause runs through us.
Stoic doctrine of fate and assent (reported by Cicero, De Fato, and Aulus Gellius).
Christian (Patristic)
The will is genuinely free and is the source of moral evil — sin comes from a free turning away from God, not from God. Yet after the Fall the will is so wounded that it cannot choose the good without grace: it is free to sin but not free, unaided, to stop sinning. Augustine wrestles all his life with reconciling this freedom, divine grace, and God's foreknowledge, insisting that foreknowledge does not compel.
On Free Choice of the Will; On Grace and Free Will; The City of God, Book V.
Scholasticism
The will is necessarily drawn to the good in general (happiness) but is free with respect to particular goods, none of which perfectly satisfies it. Free choice (liberum arbitrium) follows the intellect's deliberation, so freedom and rationality are inseparable. God, as first cause, moves the will not by coercion but by moving it to act according to its own free nature, so divine causality and human freedom are compatible.
Summa Theologiae, I, q. 83; I-II, qq. 6–17.
Protestant Reformation
Against Erasmus's defence of free will, Luther argues the fallen human will is bound: in matters of salvation it cannot turn to God by its own power but is like a beast ridden either by God or by Satan. What we call free choice is real only in outward, worldly matters; before God the will is in bondage and everything depends on grace. To claim autonomous freedom in salvation is, for Luther, to deny the sovereignty of God.
On the Bondage of the Will (De Servo Arbitrio, 1525), against Erasmus.
Early modern / materialism
Hobbes is a thoroughgoing compatibilist and determinist: liberty is the absence of external impediments, and it is fully consistent with necessity. A man acts freely when he does what he wills, even though the will itself is causally determined by the last appetite in deliberation. 'Free will' as an uncaused faculty is, for Hobbes, empty words; a free agent and a determined agent are one and the same.
Of Liberty and Necessity (1654); Leviathan, ch. 21.
Rationalism
There is no free will: everything follows with necessity from the nature of God/Nature, and the feeling of freedom is only ignorance of the causes that determine us. A thrown stone, if conscious, would believe it flies freely; so do we. Genuine 'freedom' is not undetermined choice but acting from adequate understanding of necessity — the mind's power over the passions that comes from grasping their causes.
Ethics (1677), Parts I–V; Letter 58 (the stone that thinks it is free).
Empiricism
Hume reframes the dispute as merely verbal: liberty means the power to act according to the determinations of the will (i.e. absence of constraint), and this is entirely compatible with necessity. Indeed, morality requires determinism, since praise and blame make sense only if actions flow from a person's durable character. Uncaused actions would be random, not free, and would connect to no responsible agent at all.
An Enquiry Concerning Human Understanding (1748), §8, 'Of Liberty and Necessity'.
German idealism / critical philosophy
As appearances, our actions are wholly determined by natural laws; but as rational agents we belong also to the intelligible order, where we can act from freedom. Freedom is autonomy — the will giving itself the moral law — and it cannot be proven theoretically but is a necessary presupposition of morality: 'ought implies can'. Determinism and freedom are reconciled by assigning them to the phenomenal and noumenal standpoints respectively.
Groundwork of the Metaphysics of Morals (1785); Critique of Practical Reason (1788).
German idealism / pessimism
'A man can do what he wills, but he cannot will what he wills.' Every act follows necessarily from a motive acting on an unchanging, given character, so there is no freedom in individual actions. Freedom exists, if at all, only in the timeless, extra-phenomenal act by which the will determines its own character (Kant's intelligible freedom), not in any deliberation within time. We are responsible not for our deeds but for what we are.
On the Freedom of the Will (1839).
Existentialism
Human beings are 'condemned to be free': having no fixed essence, we choose ourselves in every act and bear total responsibility, with no excuses in nature, character, or circumstance. Even not choosing is a choice, and to blame our determinations is 'bad faith', a flight from the anguish of freedom. Situation limits what we can do but never abolishes the freedom of how we take up that situation.
Being and Nothingness (1943); Existentialism Is a Humanism (1946).
Analytic philosophy
Free will is not the ability to have done otherwise but the harmony between one's first-order desires and one's second-order desires about which desires to have. A person acts freely when they act on a will they want to have — a drug addict who endorses their craving differs from one who is enslaved by it. Frankfurt's famous counterexamples also aim to show that moral responsibility does not require alternative possibilities at all.
'Freedom of the Will and the Concept of a Person' (1971); 'Alternate Possibilities and Moral Responsibility' (1969).
Analytic metaphysics (libertarian)
The 'Consequence Argument' contends that if determinism is true, our acts are the consequences of the laws of nature and events before our birth — and since we have no power over those, we have no power over our acts. Van Inwagen concludes that free will is incompatible with determinism. Yet since he also believes we do have free will and cannot fully explain how, he calls it a genuine mystery.
An Essay on Free Will (1983).