In a recent article, Libet writes: “it is only the final ‘act now’ process that produces the
voluntary act. That ‘act now’ process begins in the brain about 550 msec before the act, and it
begins unconsciously” (2001, p. 61).
“There is,” he says, “an unconscious gap of about 400
msec between the onset of the cerebral process and when the person becomes consciously aware
of his/her decision or wish or intention to act.” (Incidentally, a page later, he identifies what the
agent becomes aware of as “the intention/wish/urge to act” [p. 62].) Libet adds: “If the ‘act now’
process is initiated unconsciously, then conscious free will is not doing it.”
I have already explained that Libet has not shown that a decision to flex is made or an
intention to flex acquired at -550 ms. But even if the intention emerges much later, that is
compatible with an “act now” process having begun at -550 ms. One might say that “the ‘act
now’ process” in Libet’s spontaneous subjects begins with the formation or acquisition of a
proximal intention to flex, much closer to the onset of muscle motion than -550 ms, or that it
begins earlier, with the beginning of a process that issues in the intention.
about that (just as we can be flexible about whether the process of my baking my frozen pizza
began when I turned my oven on to pre-heat it, when I opened the oven door five minutes later to
put the pizza in, when I placed the pizza on the center rack, or at some other time). Suppose we
say that “the ‘act now’ process” begins with the unconscious emergence of an urge to flex – or
with a pretty reliable relatively proximal causal contributor to urges to flex – at about -550 ms
and that the urge plays a significant role in producing a proximal intention to flex many
milliseconds later. We can then agree with Libet that, given that the “process is initiated
unconsciously, . . . conscious free will is not doing it” – that is, is not initiating “the ‘act now’
process.” But who would have thought that conscious free will has the job of producing urges?
In the philosophical literature, free will’s primary locus of operation is typically identified as
deciding (or choosing); and for all Libet has shown, if his subjects decide (or choose) to flex
“now,” they do so consciously.
Libet asks (2001, p. 62), “How would the ‘conscious self’ initiate a voluntary act if,
factually, the process to ‘act now’ is initiated unconsciously?” Here is one answer. An “‘act
now’ process” that is initiated unconsciously may be aborted by the agent; that apparently is
what happens in instances of spontaneous vetoing, if “‘act now’ processes” start when Libet says
Now, processes have parts, and the various parts of a process may have more and less
proximal initiators. A process that is initiated by the welling up of an unconscious urge may
have a subsequent part that is directly initiated by the conscious formation or acquisition of an
intention. “The ‘conscious self’” – which need not be understood as something mysterious –
might more proximally initiate a voluntary act that is less proximally initiated by an unconscious
urge. (Readers who, like me, prefer to use ‘self’ only as an affix may prefer to say that the
acquisition or formation of a relevant proximal intention, which intention is consciously acquired
or formed, might more proximally initiate an intentional action that is less proximally initiated
Recall that Libet himself says that “conscious volitional control may operate . . . to select
and control [‘the volitional process’], either by permitting or triggering the final motor outcome
of the unconsciously initiated process or by vetoing the progression to actual motor activation”
(1985, p. 529; also see 1999, p. 54). “Triggering” is a kind of initiating. In “triggering the final
motor outcome,” the acquisition of a proximal intention would be initiating an action in a more
direct way than does an urge that initiated the process that issued in the intention. According to
one view of things, when proximal action-desires help to initiate overt actions they do so by
helping to produce pertinent proximal intentions the formation or acquisition of which directly
What Libet says about triggering here coheres with this.
Nothing warrants Libet’s claim that type II RPs are correlated with decisions or
intentions rather than with urges strong enough to issue pretty regularly in related intentions and
actions. Moreover, that, in certain settings, (roughly) proximal urges to do things arise
unconsciously – urges on which the agent may or may not act about half a second after they arise
– is no cause for worry about free will. Even if one grants Libet much more than his critics tend
to grant him, as I have done, it can be shown that his data fall well short of providing good
grounds for accepting his main theses.
I have argued that the “urge” hypothesis about what the type II RPs indicate in Libet’s studies is
less implausible than the “decision” or “intention” hypothesis. Is there an independent way to
test these hypotheses – that is, to gather evidence about whether it is (roughly) proximal urges
that emerge around -550 ms in Libet’s studies or instead decisions or intentions?
thought runs as follows: (1) all overt intentional actions are caused by decisions (or intentions);
(2) the type II RPs, which emerge around -550 ms, are correlated with causes of the flexing
actions (because they regularly precede the onset of muscle motion); so (3) these RPs indicate
that decisions are made (or intentions acquired) at -550 ms. I have shown that this line of
thought is unpersuasive. A lot can happen in a causal process that runs for 550 ms, including a
subject’s moving from having an unconscious roughly proximal urge to flex to consciously
deciding to flex “now” or to consciously acquiring a proximal intention to flex. One can reply
that, even so, 3 might be true. And, of course, I can run through my argumentation about the
veto and related matters again to remind the imaginary respondent why 3 is improbable. But
If makings of proximal decisions to flex or acquisitions of proximal intentions to flex (or
the physical events that realize these things) cause muscle motion, how long does it take them to
do that? Does it take about 550 ms? Might reaction time experiments show that 550 ms is too
long a time for this? Some caution is in order here. Lüder Deeke has distinguished among three
kinds of decision: decisions about what to do, decisions about how to do something, and
decisions about when to do something (1996, pp. 59-60). In reaction time experiments, subjects
have decided in advance to perform the assigned task – to “A,” for short – whenever they
perceive the relevant signal. When they perceive the signal, there is no need for a proximal
decision to A, as Deeke observes (p. 59). (If all decisions are responses to uncertainty about
what to do and subjects are not uncertain about what to do when they perceive the signal, there is
no place here for proximal decisions to A.) However, it is plausible that when they perceive the
signal, they acquire an intention to A now, a proximal intention. That is, it is plausible that the
combination of their conditional intention to A whenever they perceive the signal (or the neural
realizer of that intention) and their perception of the signal (or the neural realizer of that
perception) produces a proximal intention to A. The acquisition of this intention (or the neural
realization of that event) would then initiate the A-ing.
And in at least one reaction time
experiment (described shortly) that is very similar to Libet’s main experiments, the time between
the “go” signal and the onset of muscle motion is much shorter than 550 ms. This is evidence
that proximal intentions to flex – as opposed to (roughly) proximal urges to flex – emerge much
closer to the time of the onset of muscle motion than 550 ms. There is no reason, in principle,
that it should take people any longer to start flexing their wrists when executing a proximal
intention to flex in Libet’s studies than it takes them to do this when executing such an intention
in a reaction time study.
The line of reasoning that I have just sketched depends on the assumption that, in
reaction time studies, a proximal intention to A is at work. An alternative possibility is that the
combination of subjects’ conditional intentions to A whenever they perceive the signal and their
perception of the signal initiates the A-ing without there being any proximal intention to A. Of
course, there is a parallel possibility in the case of Libet’s subjects. Perhaps the combination of
their conditional intentions to A whenever they feel like it – conscious intentions, presumably –
together with a relevant feeling (urge) initiates a flexing without there being any proximal
intention to flex. If that possibility is an actuality, then Libet’s thesis is false, of course: there is
no intention to flex “now” in his subjects and, therefore, no such intention is produced by the
brain before the mind is aware of it.
The reaction time study I mentioned is reported in Haggard and Magno 1999:
Subjects sat at a computer watching a clock hand . . . whose rotation period was 2.56 s. . .
. After an unpredictable delay, varying from 2.56 to 8 s, a high-frequency tone . . . was
played over a loudspeaker. This served as a warning stimulus for the subsequent
reaction. 900 ms after the warning stimulus onset, a second tone . . . was played. [It]
served as the go signal. Subjects were instructed to respond as rapidly as possible to the
go signal with a right-key press on a computer mouse button. Subjects were instructed
not to anticipate the go stimulus and were reprimanded if they responded on catch trials.
“Reaction times were calculated by examining the EMG signal for the onset of the first sustained
burst of muscle activity occurring after the go signal” (p. 104). “Reaction time” here, then, starts
before any intention to press “now” is acquired: obviously, it takes some time to detect the
signal, and if detection of the signal helps to produce a proximal intention, that takes some time
too. The mean of the subjects’ median reaction times in the control trials was 231 ms (p. 104).
If a proximal intention to press was acquired, that happened nearer to the time of muscle motion
than 231 ms and, therefore, much nearer than the 550 ms that Libet claims is the time proximal
intentions to flex are unconsciously acquired in his studies. Notice also how close we are getting
to Libet’s time W, his subjects’ reported time of their initial awareness of something he variously
describes as an “intention,” “urge,” “wanting,” “decision,” “will,” or “wish” to move (-200 to -
150 ms). If proximal intentions to flex are acquired in Libet’s studies, Haggard and Magno’s
results make it look like a good bet that they are acquired around time W. How seriously we
should take his subjects’ reports of the time of their initial awareness of the urge, intention, or
whatever, is a controversial question, and I will say nothing about it here.
Patrick Haggard, in his contribution to a recent discussion with Libet, asserts that
“conceptual analysis could help” (Haggard and Libet 2001, p. 62). This article may be read as a
test of his assertion. In my opinion, the result is positive. Attention not only to the data but also
to the concepts in terms of which the data are analyzed makes it clear that Libet’s striking claims
about decisions, intentions, and free will are not justified by his results. Libet asserts that his
“discovery that the brain unconsciously initiates the volitional process well before the person
becomes aware of an intention or wish to act voluntarily . . . clearly has a profound impact on
how we view the nature of free will” (2004, p. 201). Not so. That, in certain settings, (roughly)
proximal urges to do things arise unconsciously or issue from causes of which the agent is not
conscious – urges on which the agent may or may not subsequently act – is a cause neither for
worry nor for enthusiasm about free will.
Adams, F. and A. Mele. 1992. “The Intention/Volition Debate.” Canadian Journal of Philosophy
Brand, M. 1984. Intending and Acting. Cambridge: MIT Press.
Coles, M. and M. Rugg. 1995. "Event-Related Brain Potentials: An Introduction." In M. Rugg
and M. Coles, eds. Electrophysiology of Mind. Oxford: Oxford University Press.
Deeke, L. 1996. “Planning, Preparation, Execution, and Imagery of Volitional Action.”
Cognitive Brain Research 3: 59-64.
Frankfurt, H. 1988. The Importance of What We Care About. Cambridge: Cambridge University
Gomes, G. 1999. “Volition and the Readiness Potential.” Journal of Consciousness Studies 6:
Haggard, P. and Eimer, M. 1999. “On the Relation Between Brain Potentials and the Awareness
of Voluntary Movements.” Experimental Brain Research 126: 128-33.
Haggard, P. and B. Libet. 2001. “Conscious Intention and Brain Activity.” Journal of
Consciousness Studies 8: 47-63.
Haggard, P. and E. Magno. 1999. Localising Awareness of Action with Transcranial Magnetic
Stimulation.” Experimental Brain Research 127: 102-07.
Haggard, P., C. Newman, and E. Magno. 1999. “On the Perceived Time of Voluntary Actions.”
British Journal of Psychology 90: 291-303.
Kane, R. 1996. The Significance of Free Will. New York: Oxford University Press.
Libet, B. 2004. Mind Time. Cambridge, Mass. Harvard University Press.
. 2001. “Consciousness, Free Action and the Brain.” Journal of Consciousness Studies 8: 59-
. 1999. “Do We Have Free Will?” Journal of Consciousness Studies 6: 47-57.
. 1992. “The Neural Time-Factor in Perception, Volition and Free Will.” Revue de
Métaphysique et de Morale 2: 255-72.
. 1989. “The Timing of a Subjective Experience.” Behavioral and Brain Sciences 12: 183-84.
. 1985. “Unconscious Cerebral Initiative and the Role of Conscious Will in Voluntary
Action.” Behavioral and Brain Sciences 8: 529-66.
Libet, B., C. Gleason, E. Wright, and D. Pearl. 1983. “Time of Unconscious Intention to Act in
Relation to Onset of Cerebral Activity (Readiness-Potential).” Brain 106: 623-42.
Libet, B., E. Wright, and A. Curtis. 1983. “Preparation- or Intention-to-Act, in Relation to Pre-
Event Potentials Recorded at the Vertex.” Electroencephalography and Clinical
Neurophysiology 56: 367-72.
Libet, B., E. Wright, and C. Gleason. 1982. “Readiness Potentials Preceding Unrestricted
‘Spontaneous’ vs. Pre-Planned Voluntary Acts.” Electroencephalography and Clinical
Neurophysiology 54: 322-35.
Mele, A. n.d. “Decisions, Intentions, Urges, and Free Will: Why Libet Has Not Shown What He
Says He Has.” In J. Campbell, M. O’Rourke, and D. Shier, eds. Explanation and Causation:
Topics in Contemporary Philosophy (MIT Press, forthcoming).
. 2003. Motivation and Agency. New York: Oxford University Press.
. 1997. “Strength of Motivation and Being in Control: Learning from Libet.” American
Philosophical Quarterly 34: 319-33.
. 1992. Springs of Action: Understanding Intentional Behavior. New York: Oxford University
Pereboom, D. 2001. Living Without Free Will. Cambridge: Cambridge University Press.
Smith, M. 2003. “Rational Capacities.” In S. Stroud and C. Tappolet, eds. Weakness of will and
practical irrationality. Oxford: Clarendon Press, pp. 17-38.
Trevena, J. and J. Miller. 2002. “Cortical Movement Preparation Before and After a Conscious
Decision to Move.” Consciousness and Cognition 11: 162-190.
1. So if the occurrence of x (at time t1) indeterministically causes the occurrence of y (at t2),
then a complete description of the universe at t1 together with a complete statement of the laws
of nature does not entail that y occurs at t2. There was at most a high probability that the
occurrence of x at t1 would cause the occurrence of y at t2.
2. In a later article, Libet writes: “the brain has begun the specific preparatory processes for the
voluntary act well before the subject is even aware of any wish or intention to act” (1992, p.
3. Some passages in which two or more of these terms are used interchangeably are quoted in
Sections 3 and 4 below. Libet, Gleason et al report that “the subject was asked to note and later
report the time of appearance of his conscious awareness of ‘wanting’ to perform a given self-
initiated movement. The experience was also described as an ‘urge’ or ‘intention’ or ‘decision’
to move, though subjects usually settled for the words ‘wanting’ or ‘urge’” (1983, p. 627).
4. For background on the generation, analysis, and use of electroencephalograms (EEGs) and
“event-related brain potentials,” including readiness potentials, see Coles and Rugg 1995.
5. I say “apparently,” because an author may wish to distinguish an intention to flex one’s wrist
from an intention to initiate a flexing of one’s wrist. I discuss initiation in Section 4. For
completeness, I observe that if we instead ignore the quotation’s first disjunct, it makes a claim
about when an intention to prepare to flex – or to prepare to initiate a flexing of one’s wrist –
6. For a more thorough discussion of the experiment, see Libet et al 1983 or Libet, Gleason et al
7. I do not wish to exclude the possibility of such settledness in commissurotomy cases.
8. Another is that they have an intention to prepare to flex, if preparing is understood in such a
way that so intending does not entail intending to flex.
9. Recall that Libet suggests that the activation event occurs between 10 and 90 ms before the
onset of muscle motion (1985, p. 537) and later revises the lower limit to 50 ms (2004, pp. 137-
10. When does the action begin in all this – that is, the person’s flexing his wrist or fingers?
This is a conceptual question, of course: how one answers it depends on one’s answer to the
question “What is an action?” Libet identifies “the actual time of the voluntary motor act” with
the time “indicated by EMG recorded from the appropriate muscle” (1985, p. 532). I favor an
alternative position, but there is no need to disagree with Libet about this for the purposes of this
article. Following Brand 1984, Frederick Adams and I have defended the thesis that overt
intentional actions (i.e., intentional actions that essentially involve peripheral bodily motion)
begin in the brain, just after the acquisition of a proximal intention; the action is proximally
initiated by the acquisition of the intention (Adams and Mele 1992). (One virtue of this view is
that it helps handle certain problems about deviant causal chains: see Mele 2003, ch. 2.) The
relevant intention may be understood, in Libet’s words, as an intention “to act now” (1989, p.
183; 1999, p. 54; 2004, p. 148), a proximal intention. (Of course, for Libet, as for me, “now”
need not mean “this millisecond.”) If I form the intention now to start running now, the action
that is my running may begin just after the intention is formed, even though the relevant
muscular motions do not begin until milliseconds later.
11. A central point of disagreement between Haggard and Libet is usefully understood as a
disagreement about when the “‘act now’ process” begins (see Haggard and Libet 2001; also see
Haggard and Eimer 1999). Haggard apparently views the onset of lateralized response potentials
(LRP), which happens “later than RP onset,” as the beginning of the process (2001, p. 53; also
see Trevena and Miller 2002).
12. Notice that in addition to “vetoing” urges for actions that are not yet in progress, agents can
abort attempts, including attempts at relatively temporally “short” actions. When batting,
baseball players often successfully halt the motion of their arms while a swing is in progress.
Presumably, they acquire or form an intention to stop swinging while they are in the process of
executing an intention to swing.
13. See Mele 1992, pp. 71-77, 143-44, 168-70, 176-77, 190-91. Those who view the connection
as direct take the view that actions begin in the brain. See n. 11.
14. For example, unlike many critics, I did not challenge Libet’s method for timing the relevant
15. Again, a more cautious formulation of the urge hypothesis is disjunctive and includes the
possibilities that what emerges around -550 ms is a (roughly) proximal urge to flex, a pretty
reliable relatively proximal causal contributor to such an urge, a (roughly) proximal urge to
“prepare” to flex, a simulation of an urge of either kind, and the motor preparedness typically
associated with such urges.
16. Hereafter, the parenthetical clauses should be supplied by the reader. Intentions, in my
view, are realized in physical states and events, and their causes are or are realized in physical
states and events. I leave it open here that although intentions enter into causal explanations of
actions, the causal work is done, not by them (qua intentions), but by their physical realizers. I
forego discussion of the metaphysics of mental causation, but see Mele 1992, ch. 2.
17. Parts of this article derive from Mele n.d. [This is a draft to be revised in light of discussion
Here is an excerpt from Alfred R. Mele, Free Will: Action Theory Meets Neuroscience:
In a recent article, Libet writes: "it is only the final ‘act now’ process that produces the voluntary act. That ‘act now’ process begins in the brain about 550 msec before the act, and it begins unconsciously" (2001, p. 61).10 "There is," he says, "an unconscious gap of about 400 msec between the onset of the cerebral process and when the person becomes consciously aware of his/her decision or wish or intention to act." (Incidentally, a page later, he identifies what the agent becomes aware of as "the intention/wish/urge to act" [p. 62].) Libet adds: "If the ‘act now’ process is initiated unconsciously, then conscious free will is not doing it."
I have already explained that Libet has not shown that a decision to flex is made or an intention to flex acquired at -550 ms. But even if the intention emerges much later, that is compatible with an "act now" process having begun at -550 ms. One might say that "the ‘act now’ process" in Libet’s spontaneous subjects begins with the formation or acquisition of a proximal intention to flex, much closer to the onset of muscle motion than -550 ms, or that it begins earlier, with the beginning of a process that issues in the intention.11 We can be flexible about that (just as we can be flexible about whether the process of my baking my frozen pizza began when I turned my oven on to pre-heat it, when I opened the oven door five minutes later to put the pizza in, when I placed the pizza on the center rack, or at some other time). Suppose we say that "the ‘act now’ process" begins with the unconscious emergence of an urge to flex – or with a pretty reliable relatively proximal causal contributor to urges to flex – at about -550 ms and that the urge plays a significant role in producing a proximal intention to flex many milliseconds later. We can then agree with Libet that, given that the "process is initiated unconsciously, . . . conscious free will is not doing it" – that is, is not initiating "the ‘act now’ process." But who would have thought that conscious free will has the job of producing urges? In the philosophical literature, free will’s primary locus of operation is typically identified as deciding (or choosing); and for all Libet has shown, if his subjects decide (or choose) to flex "now," they do so consciously.
What Libet et al. want to show is that the notion that conscious willing plays a genuine role in the etiology of a behavior such as flexing a finger is illusory. Their evidence for this is that the process in the brain that initiates the action begins some 550 milliseconds before the action and is unconscious. Only 400 msecs later does the subject become aware of his wish or urge or intention or decision to act. This is supposed to show that the conscious intention is not causally efficacious and that conscious will is an illusion.
Mele rebuts this argument by showing that it trades on a confusion of decisions/intentions on the one hand and wishes and urges on the other. To want to do X is not the same as to decide to do X. Phil may want another Fat Tire Ale but decide not to drink another because he has already decimated Bill's supply and doesn't want to presume on his host. So even if the wanting to do action A begins in the brain a half a second before the doing of A, and is unconscious, it doesn't follow that the decision to do A begins in the brain a half second before the doing of A and is unconscious. Free will is displayed in decisions and choosings, not in wants and urges.
Basically, what Mele does quite skillfully in this article is show the indispensability of accurate conceptual analysis and phenomenology for the proper interpretation of empirical findings. The real illusion here is the supposition that the empirical findings of neuroscience can by themselves shed any light.
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