Free-will & Determinism
Determinism involves the idea that all our mental states and actions, including our choices and decisions are effects necessitated by preceding causes. Thus our futures are fixed and unalterable in much the same way that the past is.
In everyday life, we suppose that free actions are the only ones for which we can hold persons morally responsible, or for which we can appropriately feel gratitude or resentment. Ordinary morality says that we are excused for doing something that would otherwise be blameworthy if we can establish that in some sense or other we had no choice in the matter and that we could not have acted otherwise.
Some philosophers, incompatibilists, believe that determinism if true destroys moral responsibility, undermines personal relations, and destroys our hopes by making all actions unfree. Freedom and determinism are incompatible.
Incompatibilists who believe that determinism is false, and hence that some actions are morally responsible, are often called libertarians.
Incompatibilists who believe that determinism is true, and moral responsibility is therefore an illusion, are sometimes called hard determinists.
Compatibilist philosophers deny that determinism has any such effect on freedom and moral responsibility. Freedom and determinism are compatible. They are sometimes called soft determinists.
Compatibilists say that we only need to be free in the sense we are not 'compelled' or 'coerced'. Our actions only need to be voluntary in this sense. All we need is voluntariness.
G E Moore‘s famous said that I am free in performing an action if I could have done otherwise, but this latter proposition is to be understood as I would have done otherwise if I had chosen. So I could have done otherwise even if determinism is true.
Moore's analysis seems to capture much of the everyday-life distinction between excused and unexcused infractions of morality. Some actions result from effective choices by the actor, and hence are free, and some do not result from such choices, and so are not free. Moore's analysis, nevertheless, seems beside the point to libertarians, because, as they say, if determinism is true, I could not have chosen otherwise in the right sense, and therefore could not have done otherwise. I could not have originated anything. Thus, they say, moral responsibility collapses.
The philosopher Ted Honderich has argued that the long running compatibilism-incompatibilism controversy springs from what it overlooks, the systematic ambiguity of talk of freedom. We each have two conceptions of freedom, not one. One involves both origination and voluntariness, while the other involves voluntariness alone. If this is so, compatibilism and incompatibilism are both false – both claim that we have just one conception of freedom or that there is one correct conception of it.
Julian Baggini and Daniel Dennett (both compatibilists), who have recently entered the fray against incompatibilist Sam Harris, both argue that the idea of freedom from any constraints whatever is incoherent. No one could ever be free all the way down.
The debate continues...
Here's a short summary of Dennett's view by Tom Clark, a former student of Dennett's. This is quoted by Harris in his book and endorsed by Dennett.
Harris is of course right that we don't have conscious access to the neurophysiological processes that underlie our choices. But, as Dennett often points out, these processes are as much our own, just as much part of who we are as persons, just as much us, as our conscious awareness. We shouldn't alienate ourselves from our own neurophysiology and suppose that the conscious self, what Harris thinks of as constituting the real self (and as many others do, too, perhaps), is being pushed around at the mercy of our neurons. Rather, as identifiable individuals we consist (among other things) of neural processes, some of which support consciousness, some of which don't. So it isn't an illusion, as Harris says, that we are authors of our thoughts and actions; we are not mere witnesses to what causation cooks up. We as physically instantiated persons really do deliberate and choose and act, even if consciousness isn't ultimately in charge. So the feeling of authorship and control is veridical. Moreover, the neural processes that (some-how—the hard problem of consciousness) support consciousness are essential to choosing, since the evidence strongly suggests they are associated with flexible action and information integration in service to behaviour control. But it's doubtful that consciousness (phenomenal experience) per se adds anything to those neural processes in controlling action.” (Tom Clark, personal communication.) (quoted from Sam Harris (2015-04-03). Free Will (Kindle Locations 260-270). Simon & Schuster, Inc. Kindle Edition.)