If 'free will' is the ability to make a choice between two or more 'action' options, it seems likely that it's an illusion.
At every instant of our lives there is a collision between the past and the present.
The past which, it appears, we cannot change includes all the almost countless 'conditions' that make us uniquely us:
... when we were born, our parents, our sex, our height, weight, intelligence (or lack of)
what education we've had, what jobs we've done, where we've travelled, who we've met ...
The present is a 'soup' of all those physical conditions of the universe (which includes us and our physical state, brain chemicals, where we are on the planet ... ). There is, as far as I'm aware, no way we can alter the ingredients of the soup in the present moment. (What we do in THIS instant will change the conditions of the NEXT instant but the present conditions seem not to be amenable to change ... they just ARE.)
So ...
What you can do, at any instant of your life is completely controlled by the meeting of your incredibly complex past and the incredibly complex present.
Those who say 'anything is possible' are being hopelessly naive. I am 164cm tall. No matter how much, at this moment, I want to be 170cm tall it is totally impossible for me to fulfill that desire. And I might want to be in the middle of the Amazonian jungle at this very moment but if I'm in the middle of London's Oxford Street I'm not going to get my heart's desire.
I might be thirsty right at this moment and you might think I can choose to get up and fetch a glass of water but wait ... is my thirst strong enough to overcome my need to finish this post? Can I overcome the upbringing I have that a job must be finished before I can walk away from it? Is my knee still too sore from this morning's run for me to be able to walk from the couch to the kitchen? Will an expected and important email plop into the IN box just as I start to get up drawing my attention away from the fact I'm thirsty?
The more you think about this instant and the restrictions placed on 'choice', the more obvious it becomes -- at least to me -- that what you can do at this instant is extremely limited and possibly so limited that what you'll do is predetermined by
PAST CONDITIONS ><PRESENT CONDITIONS
There are lots of arguments about whether free will is desirable or not but that doesn't actually change whether it exists or not.
And for those who believe in an omniscient, omnipresent deity ... my view is that omniscience is a bit like pregnancy. You can't be a little bit pregnant; you either are or you aren't. Likewise with omniscience ... you're either omniscient (you know EVERYTHING) or you aren't.
If you know everything, you know the present, the past and the FUTURE. If you know the future it is predetermined and therefore no-one can do anything other than that which the are predetermined to do = no free will.
A deity cannot, I suggest, be anything less than omniscient because this would mean not being all powerful, a condition I would suggest is impossible for the kind of deity claimed by all the major religions.
