The neuroscience of free will

7 The neuroscience of free will Can neuroscience, and the other sciences of the mind, shed light on one of the oldest and most difficult of all philosophical problems, the problem of free will and moral responsibility? 1 Some scientists believe it can. In their popular writings, these scientists often express the opinion that the sciences of the mind have shown that free will – and therefore moral responsibility – is an illusion. They argue, roughly, as follows: the sciences of the mind demonstrate that our thoughts, intentions, and (therefore) our actions are the product of deterministic processes, in the following sense: given the initial conditions (say, our genetic endowment at birth and the environment into which we were born), we had to act as we did. But if we were determined to act as we did, then we were not free, or morally responsible. Richard Dawkins, the great evolutionary biologist, has recently compared our practices of praising, blaming and punishing to Basil Fawlty’s behavior in flogging his car for breaking down, in the TV series Fawlty Towers: Doesn’t a truly scientific, mechanistic view of the nervous system make nonsense of the very idea of responsibility, whether diminished or not? Any crime, however heinous, is in principle to be blamed on antecedent conditions acting through the accused’s physiology, heredity and environment. Don’t judicial hearings to decide questions of blame or diminished responsibility make as little sense for a faulty man as for a Fawlty car? (Dawkins 2006) Of all the claims made by scientists, this is the one that probably annoys philosophers the most. Not because they regard it as wrong – most do, but some actually agree with the claim – but because it is made in apparent ignorance of literally thousands of years of debate on the question whether free will is compatible with causal determinism. There are powerful arguments for the claim that it is incompatible, but also powerful arguments on the other side. Most philosophers today are compatibilists; that is, they believe that free will is compatible with determinism. The case for compatibilism has several strands. First, compatibilists argue that the view that free will is incompatible with determinism rests upon a confusion of causation with coercion or control. I am unfree, cer- tainly, if my actions are controlled by another agent: if, for instance, my desires and beliefs are simply irrelevant to what I end up doing. If someone physically manipulates me, or holds a gun to my head, then my actions have their source in someone else, and I am not respon- sible for them. But the mere fact that determinism is true (if it is true) doesn’t show that our actions are coerced or controlled by others. When I go get myself a cheese sandwich, I do so because I want to, and this remains true even if I am determined to want a cheese sandwich. No one forces me to get a cheese sandwich. Not even determinism forces me: to be determined to do something is nothing like being forced to do it. Once again, force is something that is applied to me in spite of what I want, by others or the external world, but determinism, if it is true, works through me and my desires. We rightly resent force, external control and coercion, but we are just confused if we assimilate determinism to these external powers. Even if determinism is true, rational agents are typically free: free to do what they like. Second, compatibilists point out that if it is difficult, at least for some people, to see how free will could be compatible with determinism, it is apparently rather more mysterious how it could be compatible with indeterminism. Some scientists and laypeople who hope to rescue free will do so by appeal to quantum mechanics. Quantum mechanics is the science of subatomic particles, and is the foundation of modern physics. It is the most fundamental theory we possess for describing the physical world. Popular misconceptions to the neuroscience of free will 223 the contrary, the theory is well understood and well confirmed. However, it is highly controversial just what the world described by quantum mechanics is like, in the most basic sense. Quantum mechanics uses probabilistic rather than deterministic equations to describe the behavior of sub-atomic particles. On the so-called Copenhagen interpretation of quantum mechanics, these equations capture the nature of physical reality: the equations are probabilistic because the world is fundamentally indeterministic. This inter- pretation is the dominant one; rival interpretations attempt to save determinism by postulating hidden variables or limits on observa- tion. It is therefore controversial whether the universe is entirely deterministic. However, it is far from obvious that contemporary physics can come to the aid of the incompatibilist who wants to preserve free will. First, even if the universe is indeterministic at a sub-atomic level, it may be that these indeterminacies get washed out at the macroscopic level. The behavior of everything we can observe with the naked eye, or even with ordinary microscopes, seems determi- nistic and predictable: sub-atomic indeterminacy may simply be washed out. In that case, sub-atomic indeterminacy can be ignored: the world is deterministic for almost all practical purposes. Suppose, second, that that’s not the case; that sub-atomic indeterminacy can affect the behavior of complex macroscopic objects such as human beings. How will that help? If I am not free, despite the fact that I can do what I want when I want, how does the fact that sometimes – due to a random event – I fail to do what I want when I want to enhance my freedom? Just the opposite seems to be the case: indeterminacy would reduce, not increase, my freedom, since I cannot control the random behavior of sub-atomic particles. 2 Incompatibilists generally accept that it is a mistake to assimilate determinism to coercion or external control. But they have other reasons for thinking that determinism is incompatible with free will. They point out that we can apparently fail to be free even when we do what we want: for instance, when others the neuroscience of free will 224 manipulate our wants (Kane 1996; Pereboom 2001). Determinism might render us unfree in an analogous way. But, compatibilists respond, there are salient differences between cases in which our wants are manipulated and cases in which they are merely caused. We are someone’s puppet in the first scenario, but not in the second. Different varieties of incompatibilists part ways at this point, depending upon their beliefs about the causal structure of the world. Some incompatibilists are determinists, and therefore hold that there is no free will in our world (Pereboom 2001). Some deny that deter- minism is true; they therefore hold that some actions (at least) are free. These incompatibilists are known as libertarians (Kane 1996; Ekstrom 1999; O’Connor 2000). Obviously, we cannot hope to settle the debate whether free will is compatible with determinism, a debate that is perhaps the most complex and difficult in all of philosophy, here. It should be clear, however, that those scientists who think that the revelation that the brain is deterministic is sufficient to show that free will does not exist, without further argument, are mistaken: they do not know whereof they speak. That is not, however, to say that the sciences of the mind may not have a bearing on free will and moral responsibility. The rest of this chapter will consider two topics. First, I shall examine a global challenge to our free will and moral responsibility. Some neuroscientists have argued that we are not free, not because our actions are determined, but because we do not consciously cause our behavior. Having seen off this threat, I shall examine some of the ways in which our growing knowledge about the mind will help us to distinguish between individuals. Rather than neuroscience showing that no one is ever responsible, I shall argue, attention to its dis- coveries will help us to see who is responsible, and who is not. consciousness and freedom Some recent results in neuroscience and in psychology have been seen, by some thinkers, to present us with a fresh challenge to consciousness and freedom 225 freedom, independent of determinism. These results allegedly show that we do not consciously cause our intentions, decisions or volit- ions, and therefore our actions. If this is true, many believe, we do not act freely. As Robert Kane, one of the leaders of the recent revival of libertarianism puts it, ‘‘If conscious willing is illusory or epiphe- nomenalism is true, all accounts of free will go down, compatibilist and incompatibilist’’ (Kane 2005). In what follows, I will outline the threat, in the two forms in which it comes; I will also briefly sketch some of the ways in which philosophers have responded to it. These responses are designed to show that the experimental evidence does not, in fact, establish the claim that we do not consciously cause our actions. I shall then develop a response of my own. My response differs from the existing replies inasmuch as rather than attempting to show that the experiments are flawed, it shows that even if they successfully establish that consciousness does not play a direct role in action- causation, we can still be free and morally responsible agents. The evidence I shall cite for this claim will itself be drawn from the sciences of the mind. who decides when i decide? In essence, the claim made by both variants of the empirical chal- lenge to moral responsibility is this: consciousness plays no direct role in decision-making or volition. We do not consciously decide or consciously initiate action. Consciousness comes on the scene too late to play any causal role in action. Two thinkers have attempted, independently, to demonstrate that this is the case: Benjamin Libet, a neuroscientist, and Daniel Wegner, a psychologist. Libet’s experiment is one of the most famous in recent neuro- science: Libet and his colleagues asked subjects to flick or flex their wrist whenever they wanted to, while the experimenters recorded the ‘‘readiness potential’’ (RP) in their brains, which precedes voluntary movement by up to one second or so (Libet et al. 1983). Subjects were also asked to watch a special clock face, around which the neuroscience of free will 226 a dot of light travelled about twenty-five times faster than a normal clock (with each ‘‘second’’ therefore being about 40 milliseconds). They were required to note the position of the dot on the clock face at the time at which they became aware of the wish to move their wrist. Controlling for timing errors, the experimenters found that onset of RP preceded awareness of the wish by an average 400 milliseconds. In other words, subjects became aware of their decision to act only after its implementation was underway. Libet’s experiment has widely been seen as an empirical demonstration that there is no such thing as free will (Spence 1996; Pockett 2004). Libet has shown, the argument goes, that conscious- ness of the decision to act or of the volition comes too late to be causally effective. Consciousness is informed of the decision; it does not make it. But the agent, the target of ascriptions of praise and blame, is, if not identical to consciousness, at least more properly identified with consciousness than with the subpersonal mechan- isms that are, as a matter of fact, causally effective in action. It turns out that we do not make our decisions; they are made for us. But if we cannot control what we decide to do, then we cannot be responsible for our decisions (Zhu 2004). 3 Philosophers and cognitive scientists have not been slow to find fault with Libet’s claims. For instance, Flanagan (1996a) argues that it is consistent with Libet’s results that we consciously initiate important or ‘‘big picture’’ decisions, merely leaving the details of the implementation of these decisions to subpersonal processes. Thus, having – consciously – decided to comply with Libet’s instructions to flick their wrist when they felt like it, his subjects might have delegated the details to the unconscious mechanisms which Libet’s experiment tracks. If that’s right, then our big picture decision might after all be made consciously. As Richard Double (2004) has recently put it, this picture leaves plenty of space for a distal cause (compa- tibilist) or distal influence (libertarian) view of moral responsibility. Alfred Mele (2007) shows that it is reasonable to doubt whether Libet is right in identifying the subjective reports with the intention who decides when i decide? 227 or the decision to flick, rather than with an urge or a desire to flick. Hence, Libet’s experiment might not bear upon the role of con- sciousness in decision-making at all. Haggard (Haggard and Libet 2001) has argued that though Libet is right in thinking that we do not consciously initiate actions, our conscious intention may coincide with the specification of action. Our decision to act may not be conscious, but the choice of how precisely to act (whether, for instance, to use our left hand or our right) might nevertheless be made consciously. Finally Dennett (1991; 2003) has shown that there are deep problems with relying upon subjective judgments of simultaneity, as a consequence of which we cannot rely upon Libet’s results. In any case, Dennett argues, it is a mistake to think that there is a precise moment at which anything enters consciousness: the idea that there is any such moment is a hangover from the notion of the Cartesian Theatre, where everything comes together and is viewed by the self. Such a notion, Dennett points out, has rightly been discarded by philosophers and neuroscientists, since its truth requires that the self be an extensionless point – in other words, a Cartesian immaterial ego. Yet we all too easily fall back into modes of thought that commit us to it. Once we reject the notion of the Cartesian theatre finally and decisively, we shall recognize that consciousness is temporally smeared; not a moment, but a process with fuzzy edges. Libet’s is not the only threat to the role of consciousness in action, however. Before we assess his challenge and these responses to it, let’s set out Wegner’s version of the threat. In his book The Illusion of Conscious Will, Wegner (2002) presents a wealth of evidence for essentially the same conclusion advanced by Libet: that consciousness does not initiate action. Wegner distinguishes between what he calls the phenomenal will – our experience of our will as causally effective – and the empirical will; the actual causal mechanisms of behavior. The eponymous ‘‘illusion of conscious will’’ arises when we mistake the first for the second; when we take our experience of causation to be a direct the neuroscience of free will 228 readout of the reality. In fact, our experience is a belated and unre- liable record of action; it is neither itself a causal force, nor is it a direct reflection of the actual causal forces. Wegner argues that, far from being the cause of our actions, the phenomenal will is itself caused by the mechanisms that actually produce actions. The real causal springs of our actions are subpersonal – and therefore unconscious – mechanisms. These mechanisms produce the action, but they also produce a mental preview of the action. So long as certain conditions are satisfied, agents take this mental preview to be the real cause of the action. As Wegner (2002: 64) puts it, ‘‘People experience conscious will when they interpret their own thought as the cause of their action.’’ We fall victim to this illusion when three conditions are satisfied: the mental preview of action occurs at the right time (prior to the action, but close to the moment of its initiation), the preview is consistent with the action and the agent is unaware of other potential causes of the action. Wegner calls these three conditions of the experience of conscious will the priority, consistency and exclusivity principles. Since his account explains why we think that our preview of the action causes it, Wegner calls it the theory of apparent mental causation. In defence of his claim that conscious will is an illusion, Wegner offers us evidence that conscious will is subject to a double dissociation: its presence is not an infallible guide to our agency, and its absence is not an infallible guide to our passivity. Consider the second claim first. In a number of situations, both inside and outside the laboratory, people sincerely deny that they have acted, when in fact they have. Some kinds of paranormal experiences are good illustrations of this phenomenon. For instance, the phenomenon of table turning, which amazed so many Victorians, can be parsimo- niously explained via Wegner’s theory. In table turning, a group of people sit around a table, each with his or her hands flat on its sur- face. If they believe or hope that it will begin to turn on its own, it often, miraculously, will. The phenomenon was often interpreted as who decides when i decide? 229 evidence for the existence of supernatural beings. Of course, the participants were themselves making the table turn; the real mystery is why they sincerely denied their own agency. Wegner suggests that when many agents each contribute to the causation of an action – in other words, when the exclusivity principle is not satisfied – we may easily overlook our own contribution. The movements of the pointer on the Ouija board can be explained in precisely the same way. So, sadly, can the phenomenon of facilitated communication, in which facilitators take themselves to be merely helping profoundly disabled people to communicate, but in which the ‘‘facilitator’’ is themselves the source of the message (2002: 195–201). It seems that absence of the feeling of will is not proof of absence of agency. Whereas evidence for the second dissociation can be collected ‘‘in the wild,’’ Wegner needed to design experiments to demonstrate the possibility of the first. Most convincing here is the ‘‘I-Spy’’ experiment (Wegner 2002; Wegner and Wheatley 1999). Briefly, the experiment placed subjects in a situation in which the degree of their causal contribution to an action was unclear, due to the presence of an experimental confederate. Wegner and Wheatley found that when the confederate caused an action in this situation, the subject would over-attribute it to themselves if they were primed in accordance with the priority principle. The feeling of conscious will can be produced by priority and consistency in the absence of exclusivity, and in the absence of genuine agency. Philosophers have responded to Wegner’s claims in ways that are closely analogous to the manner in which they have responded to Libet: they have denied that Wegner has shown that consciousness does not play a direct role in action. They have pointed out that the demonstration of a double dissociation does not show anything about the normal case. Consider perception: sometimes people fail to see an object in front of them – because of a more or less spectacular dysfunction in their visual system, or because it is disguised – and sometimes they claim to see what is not there (as in many visual illusions). Perception, too, is subject to a double dissociation. But it the neuroscience of free will 230 does not follow that our impression that our percepts are caused by objects in the world is generally false (Nahmias 2002; Metzinger 2004; Bayne 2006). How strong are these responses to Libet and to Wegner? I shall not attempt to evaluate them in any detail. For what it’s worth, I suspect they are (at minimum) successful in pointing out severe problems in their arguments and experimental designs. Neither has demonstrated, anywhere near conclusively, that consciousness does not initiate action or make decisions. However, though these phi- losophers have won this battle, I suspect they will lose the war: consciousness does not, in fact, play the kind of role in action that Libet and Wegner believe to be required in order for us to be morally responsible. We should therefore get on with assessing whether, and how, moral responsibility might be compatible with the finding that consciousness does not initiate actions or make decisions. consciousness and moral responsibility Prima facie, consciousness seems required for moral responsibility. Indeed, the claim that agents must be conscious of their actions (decisions) seems to be built into our legal system, and to drive our intuitions about praise and blame. Consider the legal doctrine of mens rea. Someone is guilty of a crime (strict liability aside, which is in any case rare in the criminal law) only if they were in the requisite state of mind, where ‘‘being in a state of mind’’ seems to require consciousness. In order to be liable for the highest degree of criminal responsibility, an agent must have performed a wrongful action purposefully and knowingly. A somewhat lower degree of moral responsibility can be imputed if the agent acted recklessly, which might be understood as having been conscious of the risks of one’s conduct, but nevertheless having failed to take due care. These grades of moral responsibility seem to require consciousness: of intentions, of risks and possible consequences. To be sure, negligence does not seem to require consciousness, but it is the lowest grade of responsibility. For all grades above negligence, consciousness seems consciousness and moral responsibility 231 [...]... their action, no matter what else is true of them 2 Of course, that’s not the end of the matter There are some ingenious theories about how quantum level indeterminacy could enhance free will Kane (1996) suggests that indecision might disrupt the thermodynamic equilibrium in the brain, thereby amplifying the indeterminacy from the sub-atomic level to the level of neurons, and making it truly undetermined... because they want to They do not suffer from delusions; though they are habitual liars, they can distinguish between reality and their own fabrications They know all too well how to manipulate people, how to feign contrition, how best to turn situations to their own advantage In the absence of any clear sign of the traditional excusing conditions – ignorance, either of the nature of one’s actions, or of the. .. arguments for the claim that the alleged lag demonstrates lack of control Wegner (2004) suggests that given that the experience of conscious will is not always veridical, we ought to assume that authorship is always illusory In other words, the dissociations he demonstrates threaten nothing less than the dissolution of the self Since the feeling of willing can dissociate from the reality of willing, we... knowledge, from neuroscience and allied fields, about whether agents understand (in the relevant fashion) what they are doing when they perform a morally wrongful action, and about whether they possess relevant control over what they do Neuroscience can therefore expand our knowledge of when the excusing conditions apply neuroscience and the cognitive test Most morally relevant defects of reason are not... reflect facts about the world, and about the nature of agents in the world: Do they really know what they’re doing? Do they control their actions? The underlying logic of moral ascriptions is recognized in legal practice, as well as philosophical theories Most jurisdictions in the Western world acquit defendants if they fail a test based on the famous M’Naghten Rules, introduced in the mid-nineteenth... upon the details of the cause Morse seems to believe that the sciences of the mind cannot provide us with this kind of information; they can tell us whether or not the causes of an agent’s behavior are normal or abnormal, but nothing beyond that However, there’s every reason to believe that neuroscience can provide us with detailed knowledge that bears, precisely, on the cognitive and volitional arms of. .. to the Ontario home of his parents-in-law, where he stabbed them both He then drove to the police station, where he told police that he thought he had killed someone Only then, apparently, did he notice that his hands had been badly injured Parks was charged with the murder of his mother-in-law, and the attempted murder of his father-in-law He was acquitted, on the grounds that he had performed the. .. century in England These rules state that defendants are to be found not guilty if it is proved that: at the time of the committing of the act, the party ACCUSED was laboring under such a defect of reason, from disease of mind, as not to know the nature and quality of the act he was doing; or if he did know it, that he did not know he was doing what was wrong The M’Naghten Rules are a test of non-culpable... may well be that the only choice I can make, consistent with my values and beliefs, is for me to turn down the job But, these philosophers argue, if my decisions can only go one way, they are determined, and therefore they are not free We have already seen that there are reasons to doubt the claim that the mere fact that someone’s actions are determined entails that they are not free; the claim seems... assignment is arbitrary, and the arbitrariness of the assignment of weight transfers to the subsequent decision A power to vary the weight your reasons would have for you, were you to weigh them, introduces an element of chance into your decision-making It does not enhance freedom; it actually reduces it If we are to be capable of making free decisions, then, we do not need, or want, the power to weight our . 7 The neuroscience of free will Can neuroscience, and the other sciences of the mind, shed light on one of the oldest and most difficult of all philosophical. than the dissolution of the self. Since the feeling of willing can dissociate from the reality of willing, we ought to assume that both will and the accompanying