the question of WHETHER we have free will isn't anywhere near as interesting as the question of WHAT free will consists in. are there such things as hunvudlgs? how can you even begin to answer that question until you have some notion of what the hell a hunvudlg is supposed to be? likewise with free will...
some people think that a good theory of free will will be a theory that allows that even if determinism is true we can still have free will. why do some people think that is a good constraint on a theory of free will? because determinism might well turn out to be true that is why. even if determinism is true we still want to have free will, however, and one way to ensure this is to define free will in such a way so that even if determinism is true then we can still have free will.
another consideration is that even if quantum indeterminacies are an irreducible feature of this world and even if those indeterminacies percolate up to the atomic level indeterminacies can always be recast in determinist form. instead of saying event E CAUSES event F instead we have event E CAUSES EITHER event F (probability 0.5) OR event G (probability 0.2) OR event H (probability 0.2) OR event I (probability 0.1). Instead of deterministic laws we might have such indeterministic laws but the overall picture still looks the same as the determinist picture (but with an added layer of complication).
So... What on earth might free will be?
I surely do believe that we are morally responsible for our actions. Oh yes indeedie. So what does that moral responsibility consist in? That I could have done otherwise? That isn't consistent with determinism so it wouldn't be a good idea to say that (if determinism turns out to be true then we wouldn't have moral responsibility). Even if indeterminism is true it wouldn't have been a good idea to say that. I can't cause the probability weightings to change (there is no hidden variable to affect the probability weightings) so that move isn't going to help... So what on earth might free will be?
Simple example (why am I getting a feeling of deja vu?)...
Elliot Sober talks about a weather vane... When the weather vane is free its movements are caused by the weather and it moves sensitively to register its environment. Similarly one might consider that when our beliefs and desires (and other mental states are free) is when they are caused by the relevant portions of the world and they are appropriately and sensitively registering the relevant aspects of our environment. When those features of us cause our behaviour (and we are not prevented by others, and when we don't have abnormal desires that aren't sensitive to our needs like compulsions and abnormal beliefs that aren't sensitive to the world like delusions) then WE ARE FREE!!! And morally responsible even...
I like this idea because... Whether determinism or indeterminism turns out to be true I can still have free will and moral responsibility.
In case god is the issue...
I am a bright:
http://www.the-brights.net/
Instead of my morality being based on 'god says i should do x so i shall do x' my morality is based on the golden rule (expressed as 'do unto others' in christianity). i have some brute parts to my ethics just as the religious person has some brute parts to theirs (that god exists that they know what god wants that the bible is the world of god). but one doesn't need to believe in god to be a good person and there is no correlation between being a member of an established religion (or not) and ethical behaviour...