Free Will http://philosophy.ucsd.edu/faculty/wuthrich/ 130 Metaphysics Fall 2012
Some introductory thoughts: The traditional problem of freedom and determinism The traditional problem of freedom and determinism The Libet experiment Campbell, O Rourke, and Shier, Freedom and determinism: a framework. fundamentally: compatibility of our attitude toward ourselves and our thinking about the world problem of localisation of our actions in totality of events in the universe problem relevant because tied to moral responsibility and our attribution of it
The problem Some introductory thoughts The traditional problem of freedom and determinism The Libet experiment Laws of physics, biology, psychology, etc. govern us, and they may determine our choices. From the perspective of particles evolving since the Big Bang, there may be only one possible future. Whether you go through the upper or lower door at the end of lecture may have been decided 13 billion years ago! Examining the present in close enough detail, your choice has already been determined.
Various determinisms The traditional problem of freedom and determinism The Libet experiment 1 Logical determinism: all propositions are true or false 2 theological determinism: omniscient God knows future in every detail 3 causal determinism: every event has a cause 4 metaphysical determinism: the complete state of the universe is compatible with only one future and past history problem: compatibility between metaphysical determinism and moral freedom
Central questions Some introductory thoughts The traditional problem of freedom and determinism The Libet experiment 1 What is the thesis of metaphysical determinism? 2 What is moral freedom? 3 Is moral freedom compatible with metaphysical determinism? 4 Is metaphysical determinism true? 5 Are any persons morally free?
Traditionally (until recently) The traditional problem of freedom and determinism The Libet experiment 1 moral freedom = free will 2 necessary condition for free will: (genuinely) alternative actions scheme for addressing question (3) [and (4) and (5)]
Determinism? vs. compatibility? The traditional problem of freedom and determinism The Libet experiment Table: determinism? vs. compatibility? Yes No compatibilism incompatibilism Yes soft determinism hard determinism determinism freedom no freedom No ( hard indeterminism?) libertarianism indeterminism ( no freedom) freedom
The traditional problem of freedom and determinism The Libet experiment Alternatively: determinism? vs. freedom? Table: determinism? vs. freedom? Yes No Yes compatibilism incompatibilism soft determinism hard determinism No incompatibilism a kind of libertarianism scepticism
(1) Quantum mechanics The traditional problem of freedom and determinism The Libet experiment quantum mechanics possible indeterminism note: possible
(2) Moral freedom = free will? The traditional problem of freedom and determinism The Libet experiment equating morally relevant freedom with free will seems to presuppose the following principle Principle (Principle of Alternate Possibilities, PAP) An agent S is morally responsible for action a only if she or he had genuine alternatives to a. Harry Frankfurt (1969) challenges PAP by offering what now are known as Frankfurt cases
The traditional problem of freedom and determinism The Libet experiment A Frankfurt counterexample: Joe, Smith and Black 1 If Joe blushes at t 1, then if no one intervenes Joe will decide to kill Smith at t 2. 2 If Joe doesn t blush at t 1, then if no one intervenes Joe will not decide to kill Smith at t 2. 3 If Black sees no blush at t 1, Black will force Joe to decide to kill Smith at t 2 ; but if Black sees a blush he does nothing. 4 Joe blushes at t 1, decides to kill Smith at t 2. Joe is very naughty and morally responsible, but he couldn t do otherwise.
(3) New (formal) argument for incompatibilism The traditional problem of freedom and determinism The Libet experiment Peter van Inwagen (1975, 1983), Carl Ginet (1966, 1990): versions of so-called consequence argument modal operator: N unavoidability operator, certain form of necessity two inference rules: (α) p (β) Np N(p q) Np Nq p: arbitrary true proposition p 0 : proposition expressing the complete state of the world at time t 0 (where t 0 is a moment in time before humans came into existence) l: conjunction of all laws of nature
van Inwagen s third argument (1983, 93-104; 1989, 404f) The traditional problem of freedom and determinism The Libet experiment (1) [(p 0 &l) p] premise: determinism (2) [p 0 (l p)] (1), exportation (3) N[p 0 (l p)] (2), (α) (4) Np 0 premise (5) N(l p) (3), (4), (β) (6) Nl premise (7) Np (5), (6), (β)
Comments Some introductory thoughts The traditional problem of freedom and determinism The Libet experiment these developments led to new positions such as semi-compatibilism, which is inspired by a rejection of PAP and the success of the consequence argument: Position (Semi-compatibilism) Moral freedom is not essentially tied to the availability of genuine alternatives of action. libertarianism still rather common many incompatibilists deny traditional hypothesis of free will and defend instead, e.g., hard indeterminism, i.e., the position that incompatibilism is true, determinism is false, but we still don t have free will (Pereboom 2001)
Comments Some introductory thoughts The traditional problem of freedom and determinism The Libet experiment consensus: freedom of some sort is necessary for moral responsibility, but no consensus on what kind of freedom main groups today: 1 libertarians 2 sceptics 3 compatibilists (semi-compatibilists) agent causation : sui generis causation
The traditional problem of freedom and determinism The Libet experiment Nietzsche in Beyond Good and Evil: scepticism The causa sui is the best self-contradiction that has been conceived so far, it is a sort of rape and perversion of logic. But the extravagant pride of man has managed to entangle itself profoundly and frightfully with just this nonsense. The desire for freedom of the will in the superlative metaphysical sense, which still holds sway, unfortunately, in the minds of the half-educated; the desire to bear the entire and ultimate responsibility for one s actions oneself, and to absolve God, the world, ancestors, chance, and society involves nothing less than to be precisely this causa sui and, with more than Baron Münchhausen s audacity, to pull oneself up into existence by the hair, out of the swamps of nothingness... (1886, 21) Nietzsche 1886
Do we have free will at all? The Libet experiment The traditional problem of freedom and determinism The Libet experiment Benjamin Libet (1916-2007), researcher in the Department of Physiology of UC San Francisco first awardee of the Virtual Nobel Prize in Psychology by the University of Klagenfurt in 2003, for his pioneering achievements in the experimental investigation of consciousness, initiation of action, and free will At a congress in 1977, Libet found that a second was too long a time in a volitional movement bw the first preparations made by the brain and the actual movement Susan Blackwell: Many philosophers and scientists have argued that free will is an illusion. Unlike all of them, Benjamin Libet found a way to test it. (Commentary at Guardian Unlimited, 28 August 2007)
The traditional problem of freedom and determinism The Libet experiment Kornhuber and Deecke (1965): Bereitschaftspotentiale Kornhuber, H.H.; Deecke, L., Hirnpotentialänderungen bei Willkürbewegungen und passiven Bewegungen des Menschen: Bereitschaftspotential und reafferente Potentiale, Pflügers Arch 284 (1965): 1-17 Kornhuber and Deecke (1965): Bereitschaftspotential measurable up to one second before actual movement Bereitschaftspotential: readiness potential (RP), measure of activity in the motor cortex of the brain leading up to voluntary muscle movement absurd result, since subjects would freely choose the moment when they would raise their arm between moment of free decision and movement, there must be at least almost a second... common unchallenged assumption: that the conscious decision must be made before the brain initiates the movement Libet set out to test this assumption, and got some surprising results...
The Libet experiment (1979) The traditional problem of freedom and determinism The Libet experiment Libet, B. et al., Time of conscious intention to act in relation to onset of cerebral activity (readiness potential). The unconscious initiation of a freely voluntary act, Brain 106 (1983): 623-642. Problem: how to measure moment of conscious decision? subjects of course couldn t make a signal or tell Libet when they make the decision, as these signals themselves would of course be subject to an unknown delay of a volitional action subjects were asked to memorize the position of a pointer on a rotating dial when they made the conscious decision to move their right hand
Results of the experiment The traditional problem of freedom and determinism The Libet experiment a full quarter second before the conscious decision to move the hand was taken, the brain starts to prepare the movement... seeming conclusion to be drawn from experiment: our conscious volitional act (such as the intention to perform a certain hand movement) occur after the brain has determined what to do conscious intention to move seems to be effect of a previous subconscious decision, rather than the cause of the volitional movement!
Libet s own interpretation The traditional problem of freedom and determinism The Libet experiment Libet doesn t like this interpretation, as it would degrade humans to mere automata with our intentions and consciousness only an epiphenomenon without causal power Veto theory: we have the power to intervene by aborting an action for which the brain has already initiated action:
Problems with Libet s interpretation The traditional problem of freedom and determinism The Libet experiment Libet s own interpretation has a decisive weakness: if a conscious decision is preceded by an unconscious brain activity, then why would that not also be the case for the conscious veto? Basic question: is there an immaterial mind, or is consciousness nothing but the result of physical occurrences in the brain? In the latter case, there s no problem with the interpretation of Libet s results: if consciousness rests on physical events, there is nothing surprising in the fact that our free will is initiated by some physical process. Although he doesn t believe in free will, says neurophysiologist Wolf Singer, I go home in the evening and hold my children responsible if they have committed foolish acts, because of course I assume that they could have done otherwise.
Setting the stage: Part I Setting the stage further: Part II The main argument: Part III : incompatibilism Peter van Inwagen. The incompatibility of free will and determinism. Philosophical Studies 27 (1975): 185-199. goal: establishing incompatibility of determinism with thesis according to which we are capable of acting differently from the way we do
Part I Some introductory thoughts Setting the stage: Part I Setting the stage further: Part II The main argument: Part III state of world characterized by two necessary conditions: 1 One state does not follow another state by logical necessity. 2 Observable changes must be reflected by changes in the state; i.e., the observable supervenes on the total state of the world Definition (Determinism) Determinism is the conjunction of two theses: 1 For every instant of time, there is a proposition that expresses the state of the world at that instant. 2 If A and B are any propositions that express the state of the world at some instants, then the conjunction of A with the laws of physics entails B. (186)
Setting the stage: Part I Setting the stage further: Part II The main argument: Part III Laws of physics and laws of nature whether determinism is true depends on laws of physics (broadly conceived) but: set of laws of physics set of laws of nature reason: the latter may include psychological laws concerning voluntary behaviour of rational agents, and these voluntaristic laws may be deterministic, even they they permit free will of sorts
Part II Some introductory thoughts Setting the stage: Part I Setting the stage further: Part II The main argument: Part III [T]he concept of free will should be understood in terms of the power or ability of agents to act otherwise than they in fact do. To deny that men have free will is to assert that what a man does do and what he can do coincide. And almost all philosophers agree that a necessary condition for holding an agent responsible for an act is believing that that agent could have refrained from performing that act. (188, footnotes suppressed)
Sticking to PAP Some introductory thoughts Setting the stage: Part I Setting the stage further: Part II The main argument: Part III Frankfurt s conception of free will is rejected (this is acknowledged in the footnotes I suppressed) My reaction: this is rather disappointing, because the Frankfurt cases seem interesting and relevant to the issue; otherwise, incompatibility is pretty intuitive anyway!
Part III Some introductory thoughts Setting the stage: Part I Setting the stage further: Part II The main argument: Part III case: agent ( after due deliberation ) chooses not to perform a certain act argument to conclusion: if determinism is true, he couldn t have performed this act example: judge J freely decides not to raise his arm (to signal clemency toward a criminal about to be executed) at a certain time T T 0 : some instant before J s birth P 0 : proposition expressing the total state of the world at T 0 P: proposition that expresses the state of the world at T L: conjunction of all laws of physics
The consequence argument Setting the stage: Part I Setting the stage further: Part II The main argument: Part III 1 If determinism is true, then the conjunction of P 0 and L entails P. 2 If J had raised his hand at T, then P would be false. 3 If (2) is true, then if J could have raised his hand at T, J could have rendered P false. 4 If J could have rendered P false, and if the conjunction of P 0 and L entails P, then J could have rendered the conjunction of P 0 and L false. 5 If J could have rendered the conjunction of P 0 and L false, then J could have rendered L false. 6 J could not have rendered L false. 7 If determinism is true, J could not have raised his hand at T. [from (1) through (6)] (van Inwagen 1975, 191, fn suppressed)
Comments Some introductory thoughts Setting the stage: Part I Setting the stage further: Part II The main argument: Part III 1 follows from definition of determinism 2 from second condition regarding the state of the world 3 from idiom for could have rendered... false as introduced in Part II 4 instance of the general principle If S can render R false, then if Q entails R, then S can render Q false. (192) 5 instance of the general principle If Q is a true proposition that concerns only states of affairs that obtained before S s birth, and if S can render the conjunction of Q and R false, then S can render R false. (ibid.) This is at least questionable, since it presupposes, among other things, that there is no (relevant) backward causation.
Comments (continued) Setting the stage: Part I Setting the stage further: Part II The main argument: Part III 6 idea: if an agent can render some proposition false, then it can t be a law of physics This is a matter of conceptual truth, following from analysis of can and law. The connection between these two concepts is, according to van Inwagen, at the root of the incompatibility of free will and determinism. (193) Example: Jones, the physicist van Inwagen: even if never violated, if all physicists unconditionally accept that a violation is possible, then it is not a law But: this depends on analysis of law of physics 7 Part IV: discussion of objections to main argument
Background: Lewis on modality So, are we free to break the laws? Causation, and the consequence argument and his feigned soft determinism David Lewis. Are we free to break the laws?. Theoria 47 (1981): 112-121. masterful refutation of van Inwagen s consequence argument
Background: Lewis on modality On the Plurality of Worlds (1986) Background: Lewis on modality So, are we free to break the laws? Causation, and the consequence argument pluriverse: space of possible worlds, structured by accessibility relation R modal proposition do not have same truth value in all worlds R is binary, relata are possible worlds, is regimented by the axioms of a modal logic Lewis: R is not symmetric, not transitive (Kripke: transitive) gives raise to similarity metric in pluriverse: similar worlds are closer
Background: Lewis on modality So, are we free to break the laws? Causation, and the consequence argument Lewis on truth conditions for counterfactual conditionals Counterfactual conditionals A C is true if and only if among all A-worlds (i.e., worlds in which A is true) some C-worlds are closer to the actual world (or the world in which the counterfactual is evaluated, if not the actual world) than all C-worlds.
So, are we free to break the laws? Background: Lewis on modality So, are we free to break the laws? Causation, and the consequence argument reminder: crucial assumption for van Inwagen (proposition 6) was that we cannot break the laws Definition (Soft determinism) Soft determinism is the doctrine that sometimes one freely does what one is predestined to do; and that in such a case one is able to act otherwise though past history and the laws of nature determine that one will not act otherwise. (122, page references to reprint in Gary Watson (ed.), Free Will, Oxford 2003) Example: I was free to raise my hand, even though I didn t do it.
What if I had raised my hand? Background: Lewis on modality So, are we free to break the laws? Causation, and the consequence argument Either contradictory propositions would have been jointly true; or a historical proposition H concerning the state of the world a long time ago would not have been true; or the proposition L expressing the laws of nature of our actual world would not have been true.
What if I had raised my hand? Background: Lewis on modality So, are we free to break the laws? Causation, and the consequence argument Either contradictory propositions would have been jointly true (no: no true contradictions); or a historical proposition H concerning the state of the world a long time ago would not have been true; or the proposition L expressing the laws of nature of our actual world would not have been true.
What if I had raised my hand? Background: Lewis on modality So, are we free to break the laws? Causation, and the consequence argument Either contradictory propositions would have been jointly true (no: no true contradictions); or a historical proposition H concerning the state of the world a long time ago would not have been true (no: H would still have been true); or the proposition L expressing the laws of nature of our actual world would not have been true.
What if I had raised my hand? Background: Lewis on modality So, are we free to break the laws? Causation, and the consequence argument Either contradictory propositions would have been jointly true (no: no true contradictions); or a historical proposition H concerning the state of the world a long time ago would not have been true (no: H would still have been true); or the proposition L expressing the laws of nature of our actual world would not have been true. soft determinism (plus some shared weak assumptions) entails that if I had done what I was able to do, then some law would have been broken, i.e., something that is in fact a law, and unbroken, would have been broken, and no law (123)
Background: Lewis on modality So, are we free to break the laws? Causation, and the consequence argument That is to say, my opponent paraphrases, you claim to be able to break the very laws of nature. And with so little effort! A marvelous power indeed! Can you also bend spoons? (123)
Lewis distinguit Some introductory thoughts Background: Lewis on modality So, are we free to break the laws? Causation, and the consequence argument No, paraphrase misleading, soft determinist is only committed to a strictly weaker thesis: (Weak Thesis) I am able to do something such that, if I did it, a law would be broken. (Strong Thesis) I am able to break a law. (123) causation: breaking windows strong version identity: breaking promises strong version I am able to break a window, a promise, or a law only if I am able to do something such that, if I did it, my act would either cause or would be a window-, promise-, or law-breaking event. (124)
Background: Lewis on modality So, are we free to break the laws? Causation, and the consequence argument Soft determinism only needs the weak thesis reason for this: the counterfactual raising of my hand neither causes nor amounts to a law-breaking event and thus doesn t grant the miraculous ability to break laws (even though a law would be broken were I to raise my hand) What it does mean, however, is that a divergence miracle would have to have occurred prior to my raising my hand. The divergence miracle would have been caused by my raising my hand (though arguably the other way around).
Background: Lewis on modality So, are we free to break the laws? Causation, and the consequence argument Thus I insist that I was able to raise my hand, and I acknowledge that a law would have been broken had I done so, but I deny that I am therefore able to break a law. To uphold my instance of soft determinism, I need not claim any incredible powers. (125)
Background: Lewis on modality So, are we free to break the laws? Causation, and the consequence argument Compatibility of Lewis s own analysis of causation objection: wouldn t the raising of my hand have caused the divergence miracle according to Lewis s own analysis of causation reason: is seems the following counterfactual conditionals are true: 1 If I had raised my hand, then the divergence miracle would have occurred. 2 If I hadn t raised my hand, then the divergence miracle wouldn t have occurred. No, (1) is false; it is only the case that had I raised my hand, this some or other divergence miracle would have occurred.
Background: Lewis on modality So, are we free to break the laws? Causation, and the consequence argument 1 If I had raised my hand, then the divergence miracle would have occurred. 2 If I hadn t raised my hand, then the divergence miracle wouldn t have occurred. Had I raised my hand, then (1) would have been true (non-transitivity of accessibility relation R) But in that case, (2) wouldn t have been true, as the miracle still could have occurred, in which case it would have been canceled by a second miracle (non-symmetry of R)
Background: Lewis on modality So, are we free to break the laws? Causation, and the consequence argument A refutation of the consequence argument Recall two essential premises of van Inwagen s argument, as paraphrased by Lewis: 5 If I could have raised my hand, then I could have rendered L false. (126) 6 But I could not have rendered L false. On a weak reading of could have rendered L false (i.e., a reading supported by the Weak Thesis), premise (6) is false. On a strong reading of could have rendered L false (i.e., a reading supported by the Strong Thesis), premise (5) is false. Either way, the consequence argument is not sound.