Free will

• 1. Introduction

  ›

  Free will sits at the heart of almost every moral judgment human beings make. When courts decide whether someone deserves punishment, when we praise a friend for a difficult choice, when we blame ourselves for a failure, all of it rests on the assumption that we could have done otherwise. Ancient Greek philosophers identified this puzzle long before modern science existed, and thinkers have argued about it ever since without reaching agreement.

  The stakes are higher than they first appear. If determinism is true and every event is the inevitable product of prior causes stretching back to the origin of the universe, then no one is ever truly the author of their own actions. If free will is an illusion, then praise, blame, credit, and punishment all lose their moral foundation. And if indeterminism is true and some events are random, that introduces a different problem: random actions do not feel like free ones.

  Three large questions run through this story. Can freedom coexist with the iron logic of cause and effect? Does the foreknowledge of an all-knowing deity eliminate the open future we feel we possess? And what exactly do we mean when we say we freely choose something at all? These questions have generated incompatibilism, compatibilism, hard determinism, and a range of positions in between. The philosopher Galen Strawson has mapped out no fewer than nine distinct positions on the determinism and free will grid, and even that is a simplification.

• 2. Roots in Ancient Thought

  ›

  Aristotle, writing in the 4th century BCE, is among the earliest thinkers to whom a compatibilist picture of free will has been attributed. The key idea was that nothing hindered us from doing or choosing something, and that this absence of hindrance was what gave us control. Epictetus, writing in the 1st century CE, expressed a similar thought. Both saw freedom not as some metaphysical escape from cause and effect, but as the absence of external obstacles.

  The incompatibilist tradition has a different and slightly later origin. The scholar Susanne Bobzien has traced the first clear statement of incompatibilist free will to Alexander of Aphrodisias in the 3rd century CE. For Alexander, control depended on being causally undetermined, so that one could freely decide between doing and not doing something. The argument was not merely that obstacles were absent; it was that the future itself was genuinely open.

  The actual phrase "free will," rendered in Latin as liberum arbitrium, entered the philosophical vocabulary through Christian philosophy in the 4th century CE. For most of Western history until the Enlightenment, that phrase carried a specific meaning: the will does not have to be as it is. Both those who thought freedom was compatible with necessity and those who did not could accept that formulation. The Stoic Chrysippus, who lived roughly between 279 and 206 BCE, had already worked on the distinction between external causes and the internal disposition that receives them, a separation that would keep resurfacing across two millennia of debate.

• 3. The Determinist Challenge

  ›

  Causal determinism holds that every state of the world is completely fixed by prior states plus the laws of nature. The thought experiment associated with this view involves imagining a being who knows all facts about the past and present and all natural laws. Such a being, the argument runs, could foresee every future event down to the smallest detail, in the same way scientists already track the future positions of planets using the known laws of orbital dynamics.

  The philosopher Baron d'Holbach stands as a prominent example of what gets called hard determinism: the view that determinism is true and that free will therefore does not exist. Carl Ginet formulated a more precise version of the challenge in the 1960s, later known as the consequence argument. If determinism is true, we have no control over the events of the past that fixed our current state, and no control over the laws of nature. Since our current choices are the necessary consequences of both, we have no control over them either. Peter van Inwagen has noted that C. D. Broad had a version of this argument as early as the 1930s.

  Ginet and van Inwagen used the case of Jane sitting down on a sofa to press the point. If determinism is true, then Jane could have remained standing only if she had either generated a logical contradiction, violated the laws of nature, or changed the past. Compatibilists are therefore, on their view, committed to what the two philosophers called "incredible abilities." David Lewis offered a response: compatibilists need only be committed to the power to act differently if different circumstances had actually obtained in the past, not the power to conjure up an entirely different history.

• 4. Theological Fate and Foreknowledge

  ›

  Logical determinism raises a puzzle distinct from causal determinism. If every proposition about the future already has a truth value now, then what one will do tomorrow is already fixed as true or false today. This is the problem of future contingents, and it does not require any physical mechanism; it rests purely on the logic of truth.

  Theological determinism adds the further claim that an omniscient deity knows all of these truths in advance. Two forms of the view have been distinguished. Strong theological determinism holds that a creator deity dictates all events in history outright, leaving no room for human choice. Weak theological determinism holds that God's perfect foreknowledge makes the future inevitable, even if God does not actively intervene to produce each outcome: because what God knows will certainly come to pass, the future is already fixed.

  Boethius, Thomas Aquinas, and C. S. Lewis each attempted to defuse the theological version of the problem by appealing to non-temporal knowledge, the idea that God's knowledge is not bound by the sequence of time the way human knowledge is. If God perceives all times simultaneously rather than anticipating future events from within a present moment, the argument runs, then foreknowledge does not force any particular outcome. Soft theological determinism, or theological compatibilism, uses this and related moves to argue that divine foreknowledge is compatible with genuine human choice. The Calvinist doctrine of predestination represents the opposite pole: a supremely powerful being has fixed all events and outcomes in advance, and human choice is illusory.

• 5. Libertarian Alternatives

  ›

  Metaphysical libertarianism, in the philosophical sense, is the position that determinism is false and that genuine free will is at least possible for some people. Thomas Reid, Peter van Inwagen, and Robert Kane are among the thinkers associated with this view. They accept incompatibilism but, rather than concluding that free will is impossible, they reject determinism.

  One strand of libertarian thinking relies on quantum indeterminism. Indeterministic physical models introduce random events at the atomic or subatomic level. If some mental processes map onto this underlying physical indeterminacy, the argument goes, then the future is not fixed in the way determinism claims. Niels Bohr, one of the principal architects of quantum theory, argued, however, that there is no connection between the indeterminism of nature and the freedom of the will. The physical indeterminacy does not by itself solve the problem of origination: a random event is not obviously one for which an agent can be held responsible.

  Robert Kane developed what he called an efforts-of-will theory to address this gap. He hypothesized that indeterminism functions as a hindrance or obstacle within the agent's will, an obstacle that must be overcome by effort. On this picture, the agent is not merely the passive site of a random quantum fluctuation; the mental process of exerting effort plays an equally valid causal role alongside the physical process. Kane described such genuine authorship of difficult choices as "ultimate responsibility," and argued that this is a required condition for free will. Agent-causal theories, defended by George Berkeley and Thomas Reid among others, go further and attribute to the agent a direct power to intervene in the physical world, a power not itself causally determined by prior events.

• 6. Compatibilism and Its Varieties

  ›

  Thomas Hobbes, one of the classical compatibilists, set out the simplest version of the position: a person acts on their own free will when they act from their own desires without external compulsion, and when they could have acted otherwise if they had desired to. David Hume put it memorably by noting that what he called hypothetical liberty is universally allowed to belong to everyone who is not a prisoner in chains. Voltaire, writing in his Dictionnaire philosophique, defined liberty as simply the power to do what one wills.

  Harry Frankfurt introduced a more sophisticated picture with his hierarchical account. Frankfurt argued that agents have first-order desires, such as the desire to take a drug, and second-order desires about which first-order desires they want to prevail. He distinguished between wanton addicts, who have no second-order desire at all; unwilling addicts, who have a second-order desire not to take the drug but whose addiction overrides it; and willing addicts, who have a second-order desire to take it. On Frankfurt's account, the willing addict's choice is genuinely free because the will they act on is the will they wanted to act on, regardless of how that want itself was formed.

  Daniel Dennett offered a different compatibilist route in his book Elbow Room and developed it further in Freedom Evolves. Because the future is genuinely ill-defined for all finite beings, thanks to chaos and the inherent limits of measurement, the only well-defined thing anyone can act relative to is expectations. Since individuals can act differently from what anyone expects, Dennett argued, free will exists in the only sense that matters. Christian List has defended a version of compatibilism that distinguishes physical possibility from what he calls agential possibility, treating free will as a higher-level phenomenon on par with agency and intentionality rather than a feature of fundamental physics.

• 7. Free Will as Illusion or Pragmatic Tool

  ›

  Baruch Spinoza argued that humans believe themselves free simply because they are conscious of their actions and unconscious of the causes that determine those actions. David Hume raised the possibility that the entire centuries-long debate is a merely verbal dispute, resting on a false sensation that our actions were open when reflection shows they were necessary all along. Arthur Schopenhauer pressed this further in The World as Will and Representation, noting that everyone feels free a priori, able to start a different way of life at any moment, but then discovers a posteriori through experience that they bear the same character from beginning to end and cannot change it. In his essay On the Freedom of the Will, Schopenhauer stated directly: "You can do what you will, but in any given moment of your life you can will only one definite thing and absolutely nothing other than that one thing."

  Galen Strawson has argued that free will leads to an infinite regress. To be responsible for what one does, one must be responsible for the mental states that produced the action. But to be responsible for those mental states, one must be responsible for the states that produced them, and so on. At some point, a new causal chain must begin from nothing, and that is impossible: a person cannot create themselves or their mental states ex nihilo. Strawson calls his own view pessimism rather than hard incompatibilism, but its conclusion is similar.

  William James took a different path. He accepted free will on ethical grounds while acknowledging there was no scientific evidence for it. He saw indeterminism as a doctrine of relief: even in a bad world, it allows for the possibility that individual actions can make things better. Determinism, he argued in Pragmatism, undermines meliorism, the belief that genuine progress is possible. Ted Honderich, taking yet another route, has argued that both compatibilism and incompatibilism are false, because each assumes a single, unified concept of freedom, when in fact two distinct notions are in play: voluntary action on the one hand and genuine origination on the other. Rudolf Steiner, who collaborated on a complete edition of Schopenhauer's work, wrote The Philosophy of Freedom and argued that true freedom arrives only when inner freedom of thought and outer freedom of action are united, with will free only when motive and driving force coincide.