here's my attempt at a "scientific take" on this classic... argument:
The Heisenberg Uncertainty Principal, along with the Bell Theorem, and the work of Alain Aspect all go to imply freewill - if the fundamental interactions between subatomic particles are indeterminate, and if everything is composed of subatomic particles, then everything is indeterminate. of course, some atoms are more predictable then others - some decay faster, some decay slower. those that decay slower. those that decay slower are more predicatable for a longer period of time. those actually do have the time to form more complex molecules, and so on, until you have things as complex as life. so, for atoms whose behavior is predictable for a significant ammount of time, you can determine how they'll react with other atoms. how the molecules they make up react with other molecules, and so on. which brings us to a fundamental reality of chemistry - for every chemical reaction that can occure, there is an outcome you can be certain of - ie. if you mix an equivilant acid / base, they cancel each other out, and get carbon dioxide and water. You don't spontaniously get oil, or a tree, or anything. now if you factor in the half life of the resultant chemical, a neutral solution isn't the only thing you'll have - it'll decay into other things. but it'll take a lot of time. for a radioactive atom, it doesn't take much time. so... the more complex you are, the farther back in time your fate was pretermined, so to speak. unless of course, the mind is an emergent property, and isn't bound by the same laws our bodies are.
you can read more about the inherent randomness of "reality" here :