In our daily lives, we are free to do as we please, at least within the laws of physics and the laws of our society. Actually, excepting children and institutionalized adults, most of us are free to break the latter laws; we just choose not to keep them for the most part, whether out a sense of duty or out a fear of negative consequences.
In other contexts, our freedom doesn't seem so expansive. For example, when I think about science fiction, the inability to exceed the speed of light or travel back in time suddenly seems stifling. More seriously, what about meta-freedom? If our choices produce our actions, then what produces our choices? Can we choose what we choose? Humans make many decisions under the influence of anger, despair, lust, hunger, greed, fear, fatigue, intoxication, absent-mindedness, etc. We are reminded daily that we do not have complete self-control.
More abstractly, do we have ultimate control over even some of our choices, or are they all ultimately determined by things beyond our control? For any choice, ask yourself why you made that choice, and all sorts of causes should occur to you. Moreover, you will find that your choice can be attributed to causes outside your control. For example, what caused you to adopt your current political and religious views? How big of a causal factor was what your parents taught you? Did certain ideas simply appeal or seem right to you? Could you have forced yourself to disbelieve all these ideas? Could you have forced yourself even to want to force yourself to disbelieve all these ideas? More prosaically, why did you buy what you last bought at the grocery store? How much control do you have over which foods taste good to you and which foods are within your budget?
By now you might suspect I'm a determinist. Some people don't like determinism because they want their will to be free as in metaphysically autonomous. However, it takes a very strong form of indeterminism to actually free the will in this way. Suppose that none of your choices is fully controlled by any combination of God, the laws of physics, and the history of past physical states of the universe. Suppose a transcendent coin is flipped with each choice you make, such that you really could have chosen pepperoni on that pizza instead of sausage, or to be a Democrat instead of a Republican, if only the coin had been tails instead of heads. Well, you've got indeterminism aplenty now, but your "free will" is enslaved to a coin. "But it's not a coin; it's something far more mysterious!" Well, whatever it is, it's controlling your will.
To conclude your will is free, you must argue, "It's not a coin; it's my soul. It's me." This is a very strong claim, though. Do you really transcend all forces natural and supernatural? I'd object on empirical grounds, except that, though the observed correlation between brain states and behavior is growing tighter, there's still room for lots of miracles. For me, the decisive objection is theological. I believe God is omnipotent. Moreover, God is good, so I don't want anything to be outside his control. Also, I find rather elegant the idea that God uses a cup of physics and a dash of miracles to govern how choices are made in his universe.
