A large number of current free will theories can be sorted into one of three major categories.
The first camp, libertarian-style theories, are incompatibilist. Because determinism is false, however, we can be confident in the possibility of human agency in at least some circumstances. This is due to the believed indeterminate nature of quantum particles in the human brain. These probabilistic states can be sequenced to transfer indeterminacy to higher levels, such as the mental arena of human decision-making.
However, opponents of libertarianism point out that, even given the assumption this amplification actually occurs, indeterminism seems to be just as problematic for free will as determinism. If an event’s occurring is merely probabilistic, they say, isn’t it up to sheer luck, not human choice, whether it happens?
The second group, compatibilist-style theories, state that determinism and free will are compatible, despite the intuition that an absence of supposed “alternative possibilities” denies this freedom. To illustrate this, compatibilists have composed thought experiments in which a person lacks alternative options, but is still seemingly morally responsible for her decisions because she never sought to pursue another path.
Opponents of these theories say this process of intuition revisionism is either unreliable, incomplete or based on false assumptions. The agent who lacks alternative possibilities may in fact be acting freely — but only if one first assumes the compatibilist mantra. That would be invalid, a form of circular reasoning, they argue.
The final variety, hard incompatibilist-style theories, is the only group to deny the likelihood of free will’s existence. (Although some are simply agnostic on the point.) The lack of human freedom is a given because both determinism and indeterminism are incompatible with it, they say. If there is one possible future that cannot be altered, human choice must be mere illusion. If our actions are only up to chance, we have no control over the result. Thus, regardless of the truth value of determinism, humans must not have free will.
But hard indeterminists have detractors as well — they usually fall into one of the other two camps previously described.
So it seems that, in the horse race of free will theorizing, the final crown is yet to be claimed. Such is the fate of the current philosophic landscape: passioned debate and reasoned disagreement continue to abound.
Of that, at least, we can be certain.
