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Neurophysiology and freedom of the will

Published online: 5 February 2004� Springer-Verlag 2004

Abstract In the first two sections of the paper, some basic terminologicaldistinctions regarding ‘‘freedom of the will’’ as a philosophical problem areexpounded and discussed. On this basis, the third section focuses on theexamination of two neurophysiological experiments (one by Benjamin Libet andone by William Grey Walter), which in recent times are often interpreted asproviding an empirical vindication of determinism and, accordingly, a refutationof positions maintaining freedom of the will. It will be argued that bothexperiments fall short in this respect, and that in general—for methodicalreasons—the prospects of ever deciding the dispute about freedom of the willthrough empirical research are rather poor.

Zusammenfassung In den ersten beiden Teilen dieses Beitrags werden einigegrundlegende terminologische Unterscheidungen bezuglich ‘‘Willensfreiheit‘‘ alsphilosophisches Problem erlautert und diskutiert. Auf dieser Grundlage befasstsich der dritte Teil mit der Untersuchung zweier neurophysiologischer Experi-mente (eines von Benjamin Libet, das andere von William Grey Walter), die injungerer Zeit gern als empirische Bestatigung des Determinismus und damit alsWiderlegung von Positionen interpretiert werden, die eine Freiheit des Willensbehaupten. Wir argumentieren, dass beide Experimente in dieser Hinsichtmangelhaft sind und dass allgemein die Aussichten, den Disput uber Willens-freiheit durch empirische Forschung zu losen, aus methodischen Grunden ehergering sind.

Resume Les deux premieres sections de l’article exposent et discutent certainesdistinctions terminologiques concernant le « libre arbitre » en tant que problemephilosophique. Sur cette base, la troisieme section se concentre sur l’examen dedeux experiences neurophysiologiques (l’une par Benjamin Libet et l’autre par

Poiesis Prax (2004) 2: 275–284DOI 10.1007/s10202-003-0056-z

D. HartmannFB1, FG Philosophie, Universitat Duisburg-Essen,Campus Essen, 45117 Essen, GermanyE-mail: Dirk.hartmann@uni-essen.deTel.: +49-201-1834631

Dirk Hartmann

William Grey Walter), souvent interpretees ces derniers temps comme fournis-sant une justification au determinisme et, par consequent, une refutation despositions affirmant la liberte de la volonte. L’argumentation fait ressortir que lesdeux experiences ne parviennent pas a leur but a cet egard et que de facongenerale, pour des raisons methodologiques, les perspectives de trancher laquestion du libre arbitre par la recherche empirique sont plutot mauvaises.

1 Introductory note

The old and honorable problem of whether human will is free or determineddoes, rightly seen, comprise several distinct, though cohering questions. Firstly,there is the conceptual question of how the meaning of notions like ‘‘deter-minism’’, ‘‘will’’ and ‘‘free will’’ should be terminologically fixed. Only on thebasis of their foregoing semantic explication, the further question of whether thewill is free or determined will get a determinate sense. Regarding possibleanswers to it, we can distinguish between two kinds of arguments then—a prioriarguments, on the one hand, and empirical arguments, on the other. In thispaper, I will venture to examine some empirical arguments, more preciselycertain neurophysiologic experiments, which in recent times are often cited infavor of determinism and against positions maintaining freedom of the will.However, I will first explain and discuss certain pivotal terminological distinc-tions and deliberations related to them, before I will finally be able to focus onsaid experiments in what will be the third section of my article.

2 Freedom and determinism—some (hopefully)clarifying terminological remarks

So, terminology first: traditionally, the position of determinism is thought of asrelying on the so called ‘‘principle of causality’’ (‘‘Satz vom zureichendenGrund’’), which says that every event has a cause. Though there are exceptions, Ithink it is safe to say that most philosophers of science agree that the concepts‘‘cause’’ and ‘‘effect’’ can not be satisfyingly defined without any recourse toexperimentally established ‘‘natural laws’’, especially laws of succession.Roughly put, the members of a set of events taken together constitute a cause forsome later event if there are true natural laws (at least one of which must be alaw of succession) which, together with the assumption that the earlier eventstook place, allow to infer (relevantly) the coming to pass of the later event. Eachof the earlier events from the set may then also be called a ‘‘determining factorfor’’ or a ‘‘partial cause of’’ the later event.

Accordingly, determinism is the assumption that all events can in principle beaccounted for by taking recourse to earlier events and appropriate laws ofsuccession—’’in principle’’ only, because we neither know all natural laws, norever have a complete overview over all situations.

With respect to the notion of ‘‘freedom’’ we have to distinguish between‘‘freedom of action’’, on the one hand, and ‘‘freedom of will’’, on the other.Freedom of action is—sloppily put—instantiated if one may act according to

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one’s own wants and decisions. Here, a host of further distinctions and refine-ments can be appended. For example, we may want to distinguish the ‘‘physicalfreedom’’ of not being in chains or being paralyzed from what could be called‘‘political freedom’’, according to which one does not have to expect sanctionswhen acting in certain ways, etc. Or we may want to distinguish both physicaland political freedom from ‘‘psychic freedom’’, which consists in that thecarrying out of one’s deliberate decisions is not thwarted by counteracting‘‘inner’’ forces like emotions and drives.

With respect to my topic, what is more important than elaborating on free-dom of action and its various forms, however, is to clarify the concept of‘‘freedom of will’’. And for this it is inevitable to first explicate the concept ofwill itself. In an anti-Schopenhauerian spirit, I propose not to call every spon-taneous urge, desire or wish a manifestation of ‘‘will’’ already, at least not withinthe context of the philosophical debate. This context-related restriction isnecessary since the philosophical debate about freedom of the will is really onlyabout the question of whether the forming of decisions via reflective deliberationis causally determined (and what it would mean if it is not). Surely, theproponents of the free will thesis do not want to deny that among humanmotivational states mere urges, drives or desires can be found, which ‘‘happen’’to us plain and simple. I thus propose that only if a person P has gone through astage of deliberation about options and then eventually decides to do action A, Pis said to have formed the will or volition to do A. (In contrast to German, thereseems to be no suitable verb directly related to the English noun ‘‘will’’—’’P iswilling to do A’’ obviously means something different. Maybe ‘‘P wants to doA’’ is a sufficiently adequate verb, leaving, e.g., ‘‘P desires to do A’’ for what isnot the result of foregoing reflective deliberation. Of course, I’m fully aware thatordinary language would not restrict usages like that, but—as hinted onabove—we need some appropriate terminological conventions to be able toadequately discuss the philosophical claims.)

As said, the philosophical question regarding the freedom of the will is to beunderstood as about the status of decision-making via reflective deliberation.The connection to action is then straightforward: if even reflective decision-making is causally determined, then there is little reason to assume that humanagency as a whole is not. On the other hand, if reflective decision-making is notto be explained causally in full, then this trait seems to be transferable to allactions insofar as these can be subjected to reflexive deliberation.

The proponents of the freedom of the will thesis often claim that (in contrast,e.g., to a mere reflex) one always could have refrained from carrying out anaction. With respect to the forming of a volition, this corresponds to the claimthat one always could have decided to act differently. Here, I think that deter-minists are justified in asking what exactly this is supposed to mean, though.Indeed, it should mean more than just that the forming of a volition is notcausally determined. For this would still leave the possibility that volitions formrandomly, by mere chance—and it would be an obvious misnomer to callrandom events ‘‘free’’.

This difficulty in making ‘‘freedom of the will’’ intelligible in an anti-deter-minist sense has lead many philosophers to adopt concepts of ‘‘freedom of thewill’’ which are compatible with determinism. Such positions are therefore called‘‘compatibilistic’’.

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The most elaborate attempt to devise a compatibilist definition of ‘‘freedom ofthe will’’ can be attributed to Harry G. Frankfurt (1971). Terminologically, hedistinguishes mere wants from volitions, which are effective wants. (Note thatthis means that Frankfurt does not follow my proposal to use ‘‘to want’’ as theverb corresponding to the noun ‘‘will’’. In his use, ‘‘to want’’ is ratherinterchangeable with ‘‘to desire’’). Frankfurt furthermore makes a distinctionbetween first and second order wants and volitions. Let us elaborate a bit onthis: the intentional objects of first order wants and volitions are actions—forexample wanting to smoke a cigarette now is a first order want. A first ordervolition in Frankfurt’s understanding is a first order want that is actuallyeffective with respect to bringing about the action which is its intentional object.Second order wants and volitions analogously refer to first order wants andvolitions. For example, wanting to have a certain want or volition is a secondorder want. Frankfurt now suggests treating the concept of freedom of the willin close analogy to the concept of freedom of agency. Just like freedom of actionmeans that one is actually able (or allowed) to carry out all the actions corre-sponding to one’s first order wants, freedom of will is to mean that one iscapable to actually have the first order volitions complying with one’s secondorder wants. Hence, if someone happens to have conflicting first order wants, hiswill is free if he can form a second order volition according to which a particularwant from the set of his conflicting first order wants becomes his first ordervolition. Unfree, on the other hand, is he who at best can have the mere wantthat a certain first order want of his is also his volition.

High time for an example: someone has both the want to smoke and the wantto abstain from smoking for the sake of his health. If he is merely capable ofhaving the second order want that his first order want to abstain from smoking isalso his volition, then he is unfree, while he is free if he is capable of having thatsecond order want as a volition.

Frankfurt’s proposal indeed satisfies certain intuitions. He who is the slave ofhis wants and desires is said to be ‘‘weak-willed’’, regardless of the degree of thefreedom of action he may be enjoying. This applies even if he should somehowhappen to have no second order wants at all (like, for example, an animal), or ifhe accidentally has only such second order wants that are not in conflict with hisfirst order wants (Frankfurt’s example for this is what he calls the ‘‘willingaddict’’). As ‘‘strong-willed’’, on the other hand, we regard people who are notmere slaves of their wants, but who have got reflective control over them so thatthey are capable of pushing through their reflectively formed decisionseven against competing wants. Traditionally, one does speak of the virtues oflevel-headedness (Besonnenheit) and vigor (Tatkraft) here. The first is thecapability of being able to reflect on wants before they actually become effective,and the second is the capability of carrying out one’s reflectively formed deci-sions even against the interference of competing wants.

However, what some see as a benefit others may very well regard as ashortcoming of Frankfurt’s concept of freedom of the will, namely that, at theend of the day, it is pertaining to nothing but psychic freedom, a specific kind offreedom of action. For, according to Frankfurt, the question is whether some-one is capable of making his reflectively formed decisions effective despiteinternal counteracting factors like emotions, drives, conflicting desires and soon. But the classical philosophical topic of the freedom of the will as discussed

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by the incompatibilists—determinists and libertarians alike—does first andforemost pertain to the process of the forming of decisions as volitions them-selves—and so Frankfurt, like all compatibilists, is to face the charge of havingdone nothing but changing the topic.

This again leaves us with the classical incompatibilist choice between adeterminist position, which denies freedom of the will, and an anti-deterministposition that affirms it. We already found that the anti-determinist is obliged toexplicate a concept of freedom of the will that amounts to more than just theclaim that the forming of decisions is not causally determined. The anti-deter-minist has to show how the ‘‘free’’ reflective forming of decisions is to bedistinguished from random processes. In this respect a classical position claimsthat, while actions are not causally effected, in contrast to mere random eventsthey are, however, based on reasons. To this determinists often retort that it isprecisely the reasons which cause the actions. And then there ensues the famousdispute about whether reasons are causes or not.

3 Empirical theories and experiments on the issueof the freedom of the will

Though in my opinion indeed crucial, I will not pursue the ‘‘reasons versuscauses’’ debate here—the topic would require a paper of its own at the very least.On the other hand, in the meantime we have got enough of an overview of thedebate on freedom of the will and the main concepts related to it to be finallyable to turn to what I promised in the beginning, namely the discussion of someattempts to decide the issue empirically in favor of determinism. More precisely,I will discuss two such ventures.

The first attempt is based on certain experiments of the neurophysiologistBenjamin Libet, or—better—on specific interpretations of those experiments.For example, Gerhard Roth, in his book ‘‘Das Gehirn und seine Wirklichkeit’’(Roth 1994, pp.262), maintains that Libet’s experiments effectively settle theissue as they show that the conscious decision to act occurs after the physio-logical readiness potential which causally triggers the act (Libet 1985). A‘‘readiness potential’’ is a (relatively) slowly rising negative electric potentialwhich spreads over the cortex before motor nerves get activated. It can bemeasured non-invasively on the surface of the skull.

In Libet’s experiment, the subjects were instructed to make ‘‘spontaneouswillful decisions’’ to bend a finger or hand. ‘‘Spontaneous willful decision’’(‘‘spontaner Willensentschluß’’) is the comprehensive expression used by Roth,but it fits quite well with Libet’s approach. Libet himself writes in his originalpaper:1

The subjects were free [...] to choose to perform this act at any time thedesire, urge, decision or will should arise in them. (They were also free notto act out any given urge or initial decision to act; and each subject indeedreported frequent instances of such aborted intentions). [...] In the presentexperimental paradigm subjects agree to comply with a variety of

1Libet (loc. cit. p. 530)

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instructions from the experimenter. [...] The subject is also instructed toallow each such act to arise ‘‘spontaneously’’, without deliberately plan-ning or paying attention to the ‘‘prospect’’ of acting in advance.

With respect to a point that rotates within a period of 1–3 seconds (a so-called‘‘Wundtsche Komplikationsuhr’’), subjects are instructed to memorize the timeat which the decision was made. It turned out that the reported time for the‘‘spontaneous willful decision’’ always lay some hundreds of milliseconds afterthe time where the readiness potential kicked in.

According to Roth, this shows that the ‘‘Ego as the author of actions’’ is anillusion, for the ‘‘brain is plotting the actions’’ before one even becomes aware ofit. However, mainly because of methodical problems, the experiment can notlegitimately be interpreted this way. In this, I do not want to stress so much thevarious shortcomings regarding the experimental design which a multitude ofphysiologists and psychologists have pointed out in the discussion about Libetsexperiment.2 For me, a specific philosophical aspect is more important.According to the proposal I made above in Section 2, the ‘‘will’’ or ‘‘volition’’ tocarry out an action would be formed through a decision that brings to a close anepisode of reflective deliberation of alternatives: for example, one wonderswhether one should spend the holidays at the sea or in the mountains, and aftergiving the matter some thought, one decides in favor of holidays in the moun-tains. As long as the decision is not yet enacted, one may say that one’s ‘‘will’’ isto spend the holidays in the mountains. Please note that Libet’s experiment doesnot at all tackle the issue of whether forming a volition in this sense is deter-mined or not as he restricts his experimental setting to ‘‘spontaneous’’ decisionsactions. Libet’s subjects were instructed to refrain from forming decisions as andthe final step of a foregoing deliberation, and they were especially to refrainfrom any decisions to enact the flexing of the finger or hand at a certain futurepoint in time since this would not count as ‘‘spontaneous’’. Indeed, it is clearthat in such cases the time of the decision would have clearly preceded theinitialization of the readiness potential. Libet reports that, despite the instruc-tion, subjects nevertheless sometimes tended to plan their actions beforehand:3

In some trials, subjects did report experiencing some general preplanningor preparation to act in the near future a few seconds before the act, despitethe encouragement to be completely spontaneous.

Interestingly, he did not sort out these trials as aberrations, for:

However, subjects all insisted that the more specific urge or intention toperform the actual movement was still experienced just before each act[...]; and they clearly distinguished this urge or intention from any ad-vance feelings of preplanning to move within the next few seconds.

Here, the suggestive choice of words may get one’s attention: the proper‘‘intention’’ is what is experienced directly before the action, while episodes ofpreplanning are described as mere ‘‘feelings’’. Though I think that this assess-ment is clearly inadequate, I will not pursue this issue any further. I even will, forthe sake of the argument, agree to extend the use of the expression ‘‘forming a

2See the critics in Libet (1985)3Libet (loc. cit. p. 532)

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volition or will’’ so that it also applies if the decision is spontaneous, that is, ifthe preceding phase of deliberation is really short or even missing. I also onlyvery briefly remark that we most definitely should not assume the position thatevery action is preceded by a decision—be it well thought out or spontaneous.But what I really want to bring to the reader’s attention is that, contrary toRoth’s interpretation, even with respect to ‘‘spontaneous willful decisions’’,Libet’s findings do not at all imply the causal pre-determination of the corre-sponding actions. For it is widely acknowledged that, despite there being areadiness potential, an action can still be refrained from as long as the motornerves themselves are not yet activated. Libet himself emphasizes this in statingthat the subjects still have time to ‘‘veto’’ the carrying out of the action atthe time they experience the ‘‘urge’’, ‘‘desire’’, ‘‘intention’’ or ‘‘will’’ toperform the action. Accordingly, as the readiness potential does not trigger theaction, the ‘‘willful decision’’ to act or veto is not just an epiphenomenon—evenif they become aware of the impulse to act only after the potential has alreadybuilt up.

I had discussed Libet’s experiment as an attempt to refute freedom of the willempirically. It is referred to as such by Roth and also by other philosophers.However, it is interesting that Libet himself does not at all agree to this inter-pretation of his findings. What he thinks his results show is that ‘‘freedom of thewill’’ does not consist in persons bringing about every action through an act offree will, but rather in that they are able to veto or give in to the impulses to actwhich happen to them. This is usually left out in presentations of Libet’sexperiment by philosophers adhering to a deterministic position. Now, thatempirical results have a tendency to get overinterpreted according to one’s ownphilosophical position may be deplorable, but it’s still business as usual and assuch nothing to worry about. It’s all part of the game and, hopefully, discussionwill sort things out eventually. On the other hand, to resort to dubious sources inbacking up one’s position is a more annoying issue. And with this remark I cometo the next experiment:

In his book ‘‘Consciousness explained’’, Dennett (1991, pp.167), Daniel C.Dennett reports an experiment which—whereas conducted two decades ear-lier—could maybe count as an improved version of Libet’s. The experiment wasdone in the early 1960s by the famous neurophysiologist William Grey Walter(*1910,+1977)(1963), who—among other things—improved the EEG, whichHans Berger had invented in 1924, and thereupon discovered the delta- andtheta-waves. Furthermore, Grey Walter also counts as a veteran of artificialintelligence research. Long before Valentino Braitenberg’s ‘‘Vehicles’’ (1984), heconstructed in 1948 three-wheeled robots (so-called ‘‘tortoises’’) which usedsensors to orientate themselves with respect to light sources and obstacles whilemoving through their environment.

Now, in Grey Walter’s experiment, the subjects had electrodes implanted intotheir motor cortex connecting them to a carrousel slide projector, so that alreadya readiness potential would trigger the next slide. However, the subjects did notknow about that. They were instructed to push a button whenever they wantedto see the next picture. Dennett writes:4

4Dennett (loc. cit. p.167)

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This was a ‘‘free’’ decision, timed only by an endogenous rise in boredom,or curiosity about the next slide, or distraction, or whatever.

Even though there is no explicit mentioning of a spontaneity requirement, itstill seems that subjects were to act spontaneously, for the results of theexperiment—to which I will turn soon—would make no sense otherwise.

Of course, the button the subjects were to press was a dummy. According toDennett they reported:5

that just as they were ‘‘about to’’ push the button, but before they actuallydecided to do so, the projector would advance the slide—and they wouldfind themselves pressing the button with the worry that it was going toadvance the slide twice!

That is, the projector seemed to possess precognitive abilities regarding thesubjects decisions.

Now, to be sure, it is everything but crystal clear what it is supposed to meanto be ‘‘about to push the button without already having decided to actually doit’’. So let me devote a few remarks to this issue: with respect to the ‘‘being aboutto’’ one could imagine that the subjects were mentally prepared to press thebutton soon. And that they still had not yet ‘‘actually decided to do so’’ could beunderstood such that they nevertheless neither had formed a definite intentionregarding the precise time at which to press the button, nor excluded the pos-sibility of still getting second thoughts about the imminent button-pressing.

For the discussion to follow, we have to take into account that the build-up ofa readiness potential is neither specifically varying with the kind of bodymovement to follow, nor necessarily resulting in any such movement at all. Inthose cases where a body movement takes place, a readiness potential builds upabout 0.8 seconds before the movement, and the build-up spreads over thecortex unspecifically. Only 0.05 (0.09/0.1) seconds before the activation of thepertinent motor nerves, the unspecific readiness potential settles on the pyramidcells of the motor cortex (Kornhuber 1974). Before this point, any action canstill be abstained from (in Libet’s words: can be vetoed)—the readiness potentialthen breaks down soon.

Now, if the carrousel projector reacts to unspecific readiness potentials, then itis of course not surprising if it already advances the slide in the phase of the‘‘being about’’ to press the button. In fact, the projector then will do thisindependently of whether the subjects will really end up pressing the button orwhether they will refrain from doing so after all. It should also be no wonderthat the slide would be advanced before the ‘‘actual decision’’.

But so what? Does this result in any way support the thesis of the causaldetermination of action? Obviously not. Because of both the missing specificityand the possible intervening veto, the readiness potentials are not causes, but atmost necessary conditions of the actions they precede, and this holds true even ifthey precede any perceived impulses to act.

And now I have to address something else: despite my thorough search for it,I simply could not get hold of the original paper by Grey Walter, which Dennettcites. Additionally, I found that (apart from a multitude of philosophers

5Dennett (loc. cit. p. 167)

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drawing on Dennett’s presentation) nobody else reports about Grey Walter’sexperiment. When I asked Dennett to bring some light into this, I got thefollowing answer (email from May 10, 1999):

Grey Walter probably didn’t ever publish the talk he gave us in Oxford(which I attended), for several reasons:

1) it was not properly controlled (but too interesting not to tell a group ofstudents about!) and

2) even back then, he was probably out-of-bounds as far as the ethics ofthe experiments were concerned.

He told us that he told his patients that he needed to do follow up testingon their epilepsy post-surgically (but in fact, he was simply eager to usethem as long-term experimental subjects). These people had phone-jackscemented into their skulls for months! Or so he told us. Several neuro-scientists have recently expressed doubt that he ever did the experiments. Iremember seeing X-rays he showed us, but that proves nothing. In anyevent, you should stop your search, for it is surely futile. Others havelooked in vain, too.

Now, what are we to do with that? In his book, Dennett devotes quite somespace to the Grey Walter experiment. To the unsuspecting reader it seems like, inhis account of the ‘‘precognitive carrousel’’, Dennett is referring to a publica-tion, and in places, especially where the expression ‘‘about to’’ appears withinquotation marks, it looks as if he is indirectly quoting from it. But unfortunatelyDennett does not deem it worth mentioning that there is no publication after alland that the experiment of which he had heard almost three decades ago wasbadly controlled and maybe in the end did not even take place. Alas, I andothers (like Michael Pauen, who first told me about Dennett’s report) werewasting quite some time in a desperate search for a ghost paper. Well, Dennettshall be forgiven as he has clarified the issue in the meantime.6 But, of course, onthis background, it is a legitimate question whether one should at all mention,let alone discuss, the Grey Walter experiment anymore. Now, in my opinion, atleast the question of whether an experiment of this kind could in principleempirically decide the issue of the freedom of the will definitely remains of someinterest. And we have seen that the answer to that is ‘‘no’’.

As said, the source referred to by Dennett is nowhere to be found. That ismore often the case in science than one may think. Without any reference to asource, reports are repeatedly to be found (for example also in Roth’s book)according to which the lifting of an arm or similar reactions can be triggered bythe stimulation of certain motor areas of neurological patients, such that thepatients then claim that they had the will to do just that. The only relatedexperiment I know of was conducted by Wilder Penfield (1958) and showed theexact opposite—movements triggered by stimulation of the motor cortex wereexperienced by the subjects as having been forced on them. To be sure, one maysurmise that, for the triggering of movements which subjects would say were‘‘intended’’, ‘‘higher’’ brain areas would have to be stimulated. I am not aware

6I want to emphasize that it was Dennett himself, who, by kindly granting me permission toquote his email, made it possible to resolve the ‘‘Grey Walter issue’’ once and for all.

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of any experiment devoted to this, though. In any case, we are not licensed torely on rumors that pertinent incidents were occasionally observed during brainsurgery sessions. But let us assume—for the sake of the argument—there reallywere a successful, reproducible experiment in this vein. Would this show thatactions or the forming of volitions to act are causally determined? Again theanswer has to be ‘‘no’’. Even if—especially in artificial situations like brainsurgeries—illusions of intended body movements could be produced in a sys-tematic fashion7, this by itself would not suffice to show that there are no freeactions, but only causally determined behavior. After all, the fact that we cansystematically produce certain perceptual illusions does not show that in truththere are no perceptions, but only illusions either.

So, how would one have to verify empirically that all our acting is causallydetermined? Well, one would have to succeed in fully bringing persons undercausal control. That is, one would have to be able to use laws of succession topredict whatever they do. And in this, the means of description must not betrivial, according to the motto: ‘‘whenever a stimulus is presented, then areaction occurs. A stimulus is now presented, and indeed: a reaction occurs.’’Rather, they must be fine-grained enough to at least accommodate our estab-lished language-games pertaining to human agency (chances are they must be afair bit more articulate). Finally, the causal control must not be limited to suchsituations where the person is undergoing treatments which specifically impairthe abilities pertinent to conscious planning, deliberation and so on. I amthinking of things like drugging, mesmerizing, or invasive brain surgery. On thisbackground, the prospects of ever deciding the dispute about freedom of the willempirically seem to me quite poor, actually.

References

Braitenberg V (1984) Vehicles. MIT Press, Cambridge, MADennett DC (1991) Consciousness explained. Little, Brown and Company, New YorkFrankfurt HG (1971) Freedom of the will and the concept of a person. J Philos 68:11–25Kambartel F (1993) Kann es gehirnphysiologische Ursachen unseres Handelns geben? In:

Elepfandt A, Wolters G (eds) Denkmaschinen? Interdisziplinare Perspektiven zum ThemaGehirn und Geist. Universitatsverlag, Konstanz

Kornhuber H (1974) Cerebral cortex, cerebellum and basal ganglia: An introduction to theirmotor functions. In: Schmitt FO, Worden FG (eds) The neurosciences third study program.MIT Press, Cambridge, MA

Libet B (1985) Unconscious cerebral initiative and the role of unconscious will on voluntaryaction. (published with critical commentary from reviewers and Libet’s reply) BehavioralBrain Sci 8:529–567

Penfield W (1958) The excitable cortex in conscious man. Liverpool PressRoth G (1994) Das Gehirn und seine Wirklichkeit. Suhrkamp, FrankfurtWalter GW (1963) Presentation to the Osler Society. Oxford (talk according to Dennett 1991)

7See also the illuminating discussion in Kambartel (1993)

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