268 Contemporary Incompatibilism: Skeptical Views
About such studies Chun Siong Soon, Marcel Brass, Hans- Jochen Heinze,
and John- Dylan Haynes write: “Because brain activity in the SMA consistently
preceded the conscious decision, it has been argued that the brain had already
unconsciously made a decision to move even before the subject became aware of
it” (2008: 543). To secure further evidence about the issue, they designed an
experiment in which subjects monitored by fMRI (functional magnetic reson-
ance imaging) are instructed to do the following “when they felt the urge to do
so”: “decide between one of two buttons, operated by the left and right index
fingers, and press it immediately” (543). Soon and his colleagues found that, by
using readings from the frontopolar cortex and the other in the parietal cortex
they can predict with about 60 percent accuracy (see Soon et al. 2008, supple-
mentary figure 6; Haynes, 2011: 93) which button participants will press several
seconds in advance of the actual button press (544).
The following argument against free will emerges from these sorts of experi-
ments (Mele, 2013):
- The overt actions studied in these experiments do not have corresponding
consciously made decisions or conscious intentions among their causes
(empirical premise). - So probably no overt actions have corresponding consciously made deci-
sions or conscious intentions among their causes (inference from 1). - An overt action is a free action only if it has a corresponding consciously
made decision or conscious intention among its causes (theoretical premise). - So probably no overt actions are free actions (conclusion).
These neuroscientific studies raise complex issues which we won’t discuss in
detail here. We’ll instead restrict ourselves to canvassing a number of counter-
considerations that have been raised. One prominent objection to Premise 1,
developed in meticulous detail by Mele (2009), contends that there is no direct
way to tell which phenomena correspond to which neural events. In particular, in
the Libet studies, it is difficult to determine what the readiness potential corres-
ponds to—for example, whether it is an intention formation or decision, or just
an urge. If the readiness potential corresponds to a mere urge, and not to the for-
mation of an intention or the making of a decision, then the experimental result
will allow that the intention formation or decision is a conscious event. Thus, in
Mele’s analysis, the Libet studies leave open the possibility that intention-
formations and decisions are conscious events after all.
A second objection is due to Eddy Nahmias. Almost everyone on the con-
temporary scene who believes we have free will, whether compatibilist or liber-
tarian, also maintains that free action is caused by virtue of a chain of events that
stretches backward in time indefinitely. At some point in time these events will
be such that the agent is not conscious of them. Thus, all free actions are caused,
at some point in time, by unconscious events. As Nahmias points out, the worry
for free will raised by Libet’s studies is that the crucial factors in the causation
of action are not conscious. But, Nahmias argues, the no- free-will conclusion