Re: computationalism and supervenience

From: 1Z <>
Date: Tue, 12 Sep 2006 09:15:12 -0700

Stathis Papaioannou wrote:
> Brent Meeker writes:
> > >>I could make a robot that, having suitable thermocouples, would quickly withdraw it's
> > >>hand from a fire; but not be conscious of it. Even if I provide the robot with
> > >>"feelings", i.e. judgements about good/bad/pain/pleasure I'm not sure it would be
> > >>conscious. But if I provide it with "attention" and memory, so that it noted the
> > >>painful event as important and necessary to remember because of it's strong negative
> > >>affect; then I think it would be conscious.
> > >
> > >
> > > It's interesting that people actually withdraw their hand from the fire *before* they experience
> > > the pain. The withdrawl is a reflex, presumably evolved in organisms with the most primitive
> > > central nervour systems, while the pain seems to be there as an afterthought to teach us a
> > > lesson so we won't do it again. Thus, from consideration of evolutionary utility consciousness
> > > does indeed seem to be a side-effect of memory and learning.
> >
> > Even more curious, volitional action also occurs before one is aware of it. Are you
> > familiar with the experiments of Benjamin Libet and Grey Walter?
> These experiments showed that in apparently voluntarily initiated motion, motor cortex activity
> actually preceded the subject's awareness of his intention by a substantial fraction of a second.
> In other words, we act first, then "decide" to act.

Does Benjamin Libet's Research Empirically Disprove Free Will ?
Scientifically informed sceptics about FW often quote a famous
experiment by benjamin Libet, which supposedly shows that a kind of
signal called a "Readiness Potential", detectable by electrodes,
precedes a conscious decisions, and is a reliable indicator of the
decision, and thus -- so the claim goes -- indicates that our decisions
are not ours but made for us by unconsious processes.

In fact, Libet himself doesn't draw a sweepingly sceptical conclusion
from his own results. For one thing, Readiness Potentials are not
always followed by actions. he believes it is possible for
consicousness to intervene with a "veto" to the action:

    "The initiation of the freely voluntary act appears to begin in the
brain unconsciously, well before the person consciously knows he wants
to act! Is there, then, any role for conscious will in the performing
of a voluntary act?...To answer this it must be recognised that
conscious will (W) does appear about 150milliseconds before the muscsle
is activated, even though it follows the onset ofthe RP. An interval of
150msec would allow enough time in which the conscious function might
affec the final outcome of the volitional process."

(Libet, quoted in "Freedom Evolves" by Daniel Dennett, p. 230 )

    "This suggests our conscious minds may not have free will but
rather free won't!"

(V.S Ramachandran, quoted in "Freedom Evolves" by Daniel Dennett, p.
231 )

However, it is quite possible that the Libertarian doesn't need to
appeal to "free won't" to avoid the conclusion that free won't doesn't

Libet tells when the RP occurs using electrodes. But how does Libet he
when conscious decison-making occurs ? He relies on the subject
reporting the position of the hand of a clock. But, as Dennett points
out, this is only a report of where it seems to the subject that
various things come together, not of the objective time at which they

    Suppose Libet knows that your readiness potential peaked at second
6,810 of the experimental trial, and the clock dot was straight down
(which is what you reported you saw) at millisecond 7,005. How many
milliseconds should he have to add to this number to get the time you
were conscious of it? The light gets from your clock face to your
eyeball almost instantaneously, but the path of the signals from retina
through lateral geniculate nucleus to striate cortex takes 5 to 10
milliseonds -- a paltry fraction of the 300 milliseconds offset, but
how much longer does it take them to get to you. (Or are you located in
the striate cortex?) The visual signals have to be processed before
they arrive at wherever they need to arrive for you to make a consicous
decision of simulataneity. Libet's method presupposes, in short, that
we can locate the intersection of two trajectories: # the
rising-to-consciousness of signals representing the decision to flick #
the rising to consciousness of signals representing successive
clock-face orientations so that these events occur side-by-side as it
were in place where their simultaneity can be noted.

("Freedom Evolves" by Daniel Dennett, p. 231 )

Dennett refers to an experiment in which Churchland showed, that just
pressing a button when asked to signal when you see a flash of light
takes a normal subject about 350 milliseconds.

Does that mean that all actions taking longer than that are unconcisous

    The brain processes stimuli over time, and the amount of time
depends on which information is being extracted for which purposes. A
top tennis player can set up to design a return of service within 100
milliseconds or so. The 78 feet from base line to base line can be
traversed by a serve from Venus Williams [...] in less than 450
milliseconds [...] And since the precise timing and shape of that
return depends critically on visual information and put it to highly
appropriate use in that short a time. As Churchland showed, just
pressing a button when asked to signal when you see a flash of light
takes a normal subject about 350 milliseconds.

("Freedom Evolves" by Daniel Dennett, p. 238 )

    Our lives are full of decisions to act when the time is ripe,
revisable commitments to policies, and attitudes that will shape
responses that must be executed top swiftly to be reflectively
considered in the light of actions.

("Freedom Evolves" by Daniel Dennett, p. 239 )

    The timing tricks usually fit together seamlessly and are
incorporated into the brain's own monotoring of what it is up to, but
in artifical cicumstances (as set up by clever experimenters) the
tricks can be exposed.

("Freedom Evolves" by Daniel Dennett, p. 239 )

It is important to separate the idea that of an action being done (or
not) by you, being consciously done (or not) by you, and the being done
(or not) by you at a moment in time. The Tennis player who reacts too
quickly to have made a conscious decision is reacting too quickly ot
have made a decision at that time. On the other hand, their decisions
is not unwelcome or unexpected. It feels like their decision. And why
should it not when it is the outcome of long practice, practice of the
kind that is necessary to fulfil any taks that requires precise timing,
such as sport or music. The consciousness of the decision comes from
the cnsncious decision to train oneself to react in a certain way. The
consciousness of the act is stored, and pre-prepared, and using it we
can perform feats where Libet's 300m sec. delay would be quite

    One thing going for this hypothesis is that such judgements of
simultaneity are unnatural acts in the first place, unless they are
framed for a particular purpose, such as your trying to get your
staccato attack in sync with the conductor's downbeat, or trying to
connect with a low fastball so a to send it straight back over the
pitcher's head.

("Freedom Evolves" by Daniel Dennett, p. 235 )

Dennett's idea of "stored" conscious volition is quite in line with our
theory. Indeed, we would like to extend it in a way that Dennett does
not. We would like to extend it to stored indeterminism. Any decision
we make in exigent situations wher we do nto have the luxury of
conisdered thought must be more-or-less determinsistic -- must be
more-or-less determined by our state of mind at the time - -if they are
to be of any use at all to us. Otherwise we might as well toss a coin.
But our state of mind at the time can be formed by rumination, training
and so over a long period, perhaps over a lifetime. As such it can
contain elemetns of indeterminism in the positive sense -- of
imagination and creativity, not mere caprice.

This extension of Dennett's criticism of Libet (or rather the way
Libet's results are used by free-will sceptics) gives us a way of
answering Dennett's own criticisms of Robert Kane, a prominent defender
of naturalistic Free Will.

> These studies did not examine pre-planned
> action (presumably that would be far more technically difficult) but it is easy to imagine the analogous
> situation whereby the action is unconsciously "planned" before we become aware of our decision. In
> other words, free will is just a feeling which occurs after the fact.

It's equally easy to imagine the opposite.

> This is consistent with the logical
> impossibility of something that is neither random nor determined, which is what I feel my free will to be.

FW can be an appropriately structured mixture of the two.

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Received on Tue Sep 12 2006 - 12:16:09 PDT

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