Concept

Libertarian Free Will

Intro

Libertarian free will is the position that when you make a choice, you really could have chosen otherwise. It is the kind of freedom most people assume they have when they talk about deliberating, deciding, and being responsible. The "libertarian" label here has nothing to do with politics; it is a philosophy term that just means "free will is real and not reducible to physics."

Three claims hang together in the package. First, free will and determinism cannot both be true. If everything that happens, including every brain state, is the necessary result of prior physical events, then there is no real choice; there is just the appearance of one. Second, an agent acts freely only if she could have done otherwise in the same circumstances; the future was genuinely open and she settled it. Third, in the strongest versions, the agent herself, not a chain of prior events, is the ultimate cause of her action.

This is the kind of freedom Arminians, Molinists, and Open Theists insist on as a non-negotiable for any coherent doctrine of human responsibility, divine love, and meaningful relationship with God. They argue that genuine love and genuine sin both require it. Calvinists reject it, holding to compatibilism (you are free as long as you do what you want, even if what you want was determined). Secular hard determinism rejects free will altogether.

The standard objections to libertarian free will are that it makes choices random (if not determined, then how are they yours?) and that modern neuroscience seems to show the brain initiating actions before the conscious self knows about it (Libet experiments). Defenders answer that randomness and freedom are different things, and that the Libet readiness-potentials measure something other than the decision proper.

Quick reply in conversation: "When you decide what to order for dinner, do you actually have a real choice between the burger and the salad, or is one of them already inevitable? If the latter, what does the menu even mean?"

In full

The position that genuine free will is incompatible with causal determinism and requires the agent to have, at the moment of choice, genuine alternative possibilities, the categorical capacity to do otherwise, and to be in some appropriate sense the originator of her action rather than the downstream end of a deterministic causal chain. The view is named "libertarian" in the philosophical sense (no relation to political libertarianism) because it asserts that human freedom is real and contra-causal. It is the standard requirement of Arminianism, Molinism, and Open Theism; it is rejected by Calvinism and by secular Compatibilism and Hard Determinism.

Core claim

Three interlocking theses:

Incompatibilism, free will and causal determinism are mutually exclusive. If determinism is true, no one is genuinely free.
Principle of Alternative Possibilities (PAP), an agent acts freely (and is morally responsible for her act) only if she could have done otherwise in the same circumstances. The agent's freedom is contra-causal: at the moment of choice, more than one outcome was genuinely open.
Agent causation (some versions), the agent herself, not a chain of prior events, is the ultimate originator of free actions. The agent functions as an uncaused cause of her choices, in the sense that the choice is not the necessary consequence of any prior state.

Libertarian freedom is generally taken to be the kind of freedom presupposed by ordinary moral judgments, by deliberation (which assumes that what we decide matters to what we do), and by Scripture's commands and warnings.

Two main versions

Event-causal libertarianism (Robert Kane, The Significance of Free Will, 1996). Free choices are undetermined events caused by the agent's reasons and character, but the indeterminacy enters at certain self-forming moments where the agent's will is not yet settled. Kane's self-forming actions (SFAs) are choices in which the agent's character itself is at stake; there, indeterminacy gives the agent ultimate authorship of who he becomes.
Agent-causal libertarianism (Roderick Chisholm, "Human Freedom and the Self," 1964; Timothy O'Connor, Persons and Causes, 2000; Richard Taylor). The agent, as a substance, not as an event, directly causes her free actions. Agent causation is a primitive, irreducible to event causation; it is what distinguishes persons from non-persons.
A third (rarer) version is non-causal libertarianism (Carl Ginet, Stewart Goetz), which holds that free actions are simply uncaused, with the agent's reasons being explanatory rather than causal.

Biblical foundation (libertarian reading)

Choose this day, Josh 24:15 ("choose for yourselves today whom you will serve"); Deut 30:19 ("I have set before you life and death... so choose life").
God's grief at unchosen love, Matt 23:37 ("how often I wanted... and you were unwilling"); Acts 7:51 ("you always resist the Holy Spirit").
Genuine deliberation, 1 Cor 10:13 (with every temptation God provides "the way of escape"); Rom 6:16-19 (presenting members as slaves to obedience or sin, implies a real choice).
Whoever wills may come, John 7:17 ("if anyone wills to do His will, he shall know"); Rev 22:17 ("let the one who wishes take the water of life without cost").
Calls to repent, pervasive across Scripture; the call presupposes the genuine possibility of either response.

The standard libertarian argument: God's commands, warnings, exhortations, and grief over disobedience presuppose that the obedience-or-disobedience was a real fork in the road; if the choice was determined, the structure of the call collapses into theater.

Historical development

Early Church Fathers (2nd-4th c.), strongly libertarian: Justin Martyr, Irenaeus (Against Heresies IV.37), Origen (De Principiis III.1), Tertullian, John Chrysostom. The dominant pre-Augustinian position, especially in the East, was robust libertarian freedom against Gnostic and Stoic determinism.
Augustine, early libertarian (De Libero Arbitrio); shifts toward a compatibilist account of bound-will under sin in the late anti-Pelagian writings (De Praedestinatione Sanctorum).
Eastern Orthodox tradition, preserves a strongly libertarian / synergistic account of autexousion (self-determination) throughout (Maximus the Confessor, John of Damascus, contemporary Orthodox theology).
Aquinas, a nuanced position: the will is naturally inclined to the good, but among finite goods the will is genuinely undetermined.
Molina, Suárez (16th c. Jesuit), defend libertarian freedom against the more determinist Bañezian Thomism. Middle knowledge presupposes libertarian counterfactuals.
Arminius and the Remonstrants (early 17th c.), libertarian freedom under prevenient grace becomes a distinguishing mark of Reformed-Protestant Arminianism.
Reid, Kant (18th c.), Reid's defense of active power; Kant's transcendental freedom (the noumenal self).
20th-21st c. analytic libertarianism. Roderick Chisholm, "Human Freedom and the Self" (1964); Peter van Inwagen, An Essay on Free Will (1983), the Consequence Argument (if determinism is true, our acts are consequences of past states + laws, neither of which we control); Robert Kane, The Significance of Free Will (1996); Timothy O'Connor; Stewart Goetz.

The Consequence Argument (van Inwagen)

The principal contemporary argument for incompatibilism (and so for libertarian freedom, given that we do have responsibility):

If determinism is true, then our acts are the consequence of (i) the laws of nature and (ii) states of the universe long before we were born.
We have no power over (i) or (ii).
We have no power over the consequences of things we have no power over.
Therefore, we have no power over our acts.

The conclusion: if we do have power over our acts (as ordinary moral life and Scripture both presuppose), determinism is false.

Frankfurt cases (the principal challenge)

Harry Frankfurt's "Alternate Possibilities and Moral Responsibility" (1969) constructs cases in which an agent does X on his own, while a counterfactual intervener would have made him do X had he been about to deviate. The agent could not have done otherwise (the intervener guarantees X), yet we still hold him responsible because he did X on his own. Frankfurt concludes PAP is false.

Libertarian replies:

Flickers of freedom (David Widerker, Carl Ginet), even in Frankfurt cases, some alternative possibility (e.g., the agent's prior intention-formation, his decision moment) remains; PAP holds at the relevant level.
Dilemma defense (Kane, Widerker), Frankfurt cases either presuppose determinism (begging the question) or leave open exactly the libertarian alternatives PAP demands.
The Frankfurt-cases literature is one of the most active fields in contemporary action theory; the dispute has not been resolved.

Spread of positions (where Libertarian Free Will stands)

Required by Arminianism, Molinism, and Open Theism, all three need libertarian freedom to ground genuine creaturely response, conditional election, and (for Open Theism) the open future.
Rejected by Calvinism, which holds Compatibilism as the only account consistent with sovereign decree.
Rejected by Hard Determinism, which agrees with the libertarian's requirement that responsibility needs ultimate origination but denies we have it.
The standard secular position in contemporary philosophy is not libertarianism but compatibilism (Frankfurt, Dennett, Fischer); libertarianism is a minority view in academic philosophy of mind, though defended by major figures (Kane, O'Connor, van Inwagen).
The default theological position in Catholicism (with significant Thomist nuance), Eastern Orthodoxy, Wesleyan-Methodist traditions, most contemporary evangelicalism, and the early Church Fathers.

Standard objections (steel-manned)

The randomness objection (the principal philosophical objection). If a free choice is genuinely undetermined by prior states, it would seem to be random, and a random event is no more an exercise of agency than a determined one. Libertarian replies: agent causation is not random; the agent herself causes the choice, and her reasons explain it without necessitating it. Or: indeterminacy is located in self-forming actions where the agent's character is in formation (Kane).
The neuroscience objection. Libet-style studies show that brain activity precedes conscious awareness of choosing. Libertarian replies: Libet's interpretation is contested; the readiness potential may be preparation rather than decision; the conscious "veto" remains the seat of genuine agency; brain activity correlated with choice is not yet brain activity determining choice.
The grounding / mystery objection. Agent causation posits a kind of causation foreign to the rest of nature. Libertarian replies: persons are exactly the kind of thing where novel categories are appropriate; the alternative reductions (compatibilism, hard determinism) fail to ground responsibility.
The theological / sovereignty objection (Calvinist). Libertarian freedom undermines exhaustive divine sovereignty; if creaturely choices are genuinely undetermined, God's plan is at the mercy of those choices. Libertarian replies: this conflates causation with foreknowledge (cf. Foreknowledge vs Causation); on Molinist accounts, middle knowledge preserves both libertarian freedom and exhaustive providence.

Tensions

The relation between libertarian freedom, agent causation, and the natural sciences is contested; emergentist accounts (O'Connor) try to bridge the gap.
Whether libertarian freedom is necessary for moral responsibility (the libertarian / Calvinist crux) remains the central dispute and shows no sign of resolution.
The Frankfurt-cases literature has produced a generation of refinements on both sides without consensus.