Vernon asked:

What does the study of identical twins, who were raised in different circumstances, say about the
concept of free will? It seems psychologists, with their talk about nature and nurture being the factors
that affect behavior, imply that they don't believe in "free will". I used to, but there was something in
my genes or my environment which caused me to rethink this belief. I'm also thinking, that this would
be an actual, real world, experiment with which philosophers could do a scientific study.

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Since 'identical' twins aren't, it wouldn't say anything, because the experiment you're envisioning
would require that two people be identical down to the molecular level, then see whether they
behaved differently in the same environment. But there are no two people with identical neural nets;
we don't have enough genetic information to determine dendritic connections between all our
neurons, much less details like the configuration of presynaptic membranes. No way.

But let's assume that we coulddo it, i.e., create, and determine that we have created, two identical
people. Further, let's assume that we could create identical environments for those two people (an
impossible job in itself, but never mind). Then, we assume, given identical inputs, i.e., sensations, that
we would have identical outputs (including thoughts). Here's the problem with that. Given that our
neural nets are complex enough so that neural dynamics are chaotic (a reasonable assumption, for
which Walter Freeman, for example, has presented evidence), then in a chaotic system, we have
points at which the system can move to two or more states from some initial state, with infinitesimal
perturbations determining the different path. That is, something literally so small or faint that we could
not even in theory measure it could change the neural dynamics of the two systems (the peoples'
brains) in different ways, so that the two people would then be and behave differently. We would then
be in the position of having to ask whether such an undetectable event occurred, not something a
scientist likes to contemplate.

Here's the other problem. As far as I know, there is no empirical way to decide the question of free
will. First, no one knows what it is. I mean, think about it. Just what does "free" mean? Free to do
what you decide to do? Free of physical laws? Free to decide? Well, we have the first and third, as far
as we can tell, don't we? Why aren't we free to decide, even if our decisions are determined by
physical laws? Let's look at that point in a bit more detail. On the one hand, we want our decisions
free of physical determination. On the other hand, unless we want randomness, our decisions have to
be determined by something.Mental laws? Wouldn't we be just as "unfree" if our decisions were
determined by mental laws (whatever those might be) as physical?

So we seem to want something which is neither determined nor random (and the latter includes, of
course, weighed chance, like dice or quantum uncertainties). Now, what could that possibly be? I
have no idea. We seem caught between random decisions and decisions thoroughly caused by some
kind of antecedents which, ultimately (if we want to avoid regress), we have no control over. These
are the concepts we work with at this point; maybe there are others we will discover. Thus, can we
claim to know all physical laws? There might be some which give us "free will", even though we don't
know what that is, might there not? My point is that our feeling of free decision may or may not be an
illusion; we simply do not know, so we might as well act as if it is not. If we do not act that way, we
avoid responsibility for consequences that we may well be responsible for; if we do act that way, we
assume such responsibility, and that assumption would seem to be the most ethical default position.

Steven Ravett Brown