"Philosophers have argued that either Determinism is true or Indeterminism is true, but also that Free Will either exists or it does not. This creates four possible positions. Compatibilism refers to the view that free will is, in some sense, compatible with Determinism. The three Incompatibilist positions, on the other hand, deny this possibility. They instead suggest there is a dichotomy between determinism and free will (only one can be true).
To the Incompatibilists, one must choose either free will or Determinism, and maybe even reject both. The result is one of three positions:
Metaphysical Libertarianism (free will, and no determinism) a position not to be confused with the more commonly cited Political Libertarianism.
Hard Determinism (Determinism, and no free will).
Hard Indeterminism (No Determinism, and no free will either).
Thus, although many Determinists are Compatibilists, calling someone a 'Determinist' is often done to denote the 'Hard Determinist' position.
The Standard argument against free will, according to philosopher J. J. C. Smart focuses on the implications of Determinism for 'free will'.[10] He suggests that, if determinism is true, all our actions are predicted and we are not free; if determinism is false, our actions are random and still we do not seem free.
In his book, The Moral Landscape, author and neuroscientist Sam Harris mentions some ways that determinism and modern scientific understanding might challenge the idea of a contra-causal free will. He offers one thought experiment where a mad scientist represents determinism. In Harris' example, the mad scientist uses a machine to control all the desires, and thus all the behaviour, of a particular human. Harris believes that it is no longer as tempting, in this case, to say the victim has "free will". Harris says nothing changes if the machine controls desires at random - the victim still seems to lack free will. Harris then argues that we are also the victims of such unpredictable desires (but due to the unconscious machinations of our brain, rather than those of a mad scientist). This implicitly assumes a philosophy of materialism, which could be disputed along with Harris's hard determinism. Based on this introspection, he writes "This discloses the real mystery of free will: if our experience is compatible with its utter absence, how can we say that we see any evidence for it in the first place?"[11] adding that "Whether they are predictable or not, we do not cause our causes."[12] That is, he believes there is compelling evidence of absence of free will." -
http://en.wikipedia.org/wiki/Determinist
"Other proponents of emergentist or generative philosophy, cognitive sciences and evolutionary psychology, argue that determinism is true.[24][25][26][27] They suggest instead that an illusion of free will is experienced due to the generation of infinite behaviour from the interaction of finite-deterministic set of rules and parameters. Thus the unpredictability of the emerging behaviour from deterministic processes leads to a perception of free will, even though free will as an ontological entity does not exist.[24][25][26][27] Certain experiments looking at the Neuroscience of free will can be said to support this possibility."
"Some (including Albert Einstein) argue that our inability to predict any more than probabilities is simply due to ignorance.[36] The idea is that, beyond the conditions and laws we can observe or deduce, there are also hidden factors or "hidden variables" that determine absolutely in which order photons reach the detector screen. They argue that the course of the universe is absolutely determined, but that humans are screened from knowledge of the determinative factors. So, they say, it only appears that things proceed in a merely probabilistically determinative way. In actuality, they proceed in an absolutely deterministic way."
"The challenge for determinism is to explain why and when decay occurs, since it does not seem to depend on external stimulus. Indeed, no extant theory of physics makes testable predictions of exactly when any given atom will decay. At best scientists can discover determined probabilities in the form of the element's half life.
The time dependent Schrödinger equation gives the first time derivative of the quantum state. That is, it explicitly and uniquely predicts the development of the wave function with time.
So if the wave function itself is reality (rather than probability of classical coordinates), quantum mechanics can be said to be deterministic.
According to some,[citation needed] quantum mechanics is more strongly ordered than Classical Mechanics, because while Classical Mechanics is chaotic (appears random, specifically due to minor details - perhaps at a smaller scale), quantum mechanics is not. For example, the classical problem of three bodies under a force such as gravity is not integrable, while the quantum mechanical three body problem is tractable and integrable, using the Faddeev Equations.[clarification needed] This does not mean that quantum mechanics describes the world as more deterministic, unless one already considers the wave function to be the true reality. Even so, this does not get rid of the probabilities, because we can't do anything without using classical descriptions, but it assigns the probabilities to the classical approximation, rather than to the quantum reality.
Asserting that quantum mechanics is deterministic by treating the wave function itself as reality implies a single wave function for the entire universe, starting at the origin of the universe. Such a "wave function of everything" would carry the probabilities of not just the world we know, but every other possible world that could have evolved. For example, large voids in the distributions of galaxies are believed by many cosmologists to have originated in quantum fluctuations during the big bang."
