There are a few threads about determinism here and a few about interpretations of quantum mechanics, so I thought I'd start one that combines them. Determinism is nicely defined by the Stanford Encyclopedia of Philosophy as: Ref: Stanford Encyclopedia I think one of the more contentious phrases used in this definition is the term, "natural law" which is explained this way: What exactly does "laws of nature" entail? I think its important to first recognize we're not talking about "supernatural laws" when referring to determinism. The point is, are any laws of nature not deterministic? From reading this article, and many others like it, quantum mechanics is always mentioned as a non-deterministic law. Here, the Stanford Encyclopedia mentions it: In conclusion, the article does not resolve whether nature is deterministic or not. We can say quantum mechanics is 'deterministic' but that doesn't address a number of issues, namely the random nature of radioactive decay nor why one possible evolution of the Schrödinger equation is observed and another is not. This is also discussed in the article. If nature has a 'random' element to it or not however, is less of a concern regarding consciousness for two reasons. There are two more immediate considerations. 1) At the macroscopic scale, such things as quantum interactions seem to cancel out. Even if they are statistical or random, does that have anything to do with consciousness? Generally this seems to be dismissed as a red herring. Who cares if things are truly random or not at the microscopic scale of an atom? Our brains, the contention is, are governed not by quantum interactions, but by gross interactions between millions or billions of molecules at any given 'switch' junction. So regardless of whether there is any truly random mechanism in the universe, by the time you add up all the large numbers of interactions, the mind is deterministic in the sense that it is not governed by individual molecular interactions, but by enormous numbers of interactions which may be very (exceedingly) slightly chaotic, but far from random. 2) Even if quantum mechanics provides for a random mechanism, and even if our brain utilizes this mechanism to function, a switch of some type that produces a random outcome is not special enough in any way to explain why consciousness should emerge. One can insert a pseudo-random switch into a computer, so computationalism is not discouraged by an indeterminate or random mechanism. If our brains operate on a macroscopic scale where quantum interactions cancel out, and even if it doesn't, even if there are random mechanisms that our brains rely on to function, the idea that the universe is essentially deterministic remains a valid concept with respect to consciousness. Given this perspective on the subject, and only this perspective on the subject, it seems it doesn't matter if the world is deterministic or not. Now I still have to add though, that there is one concept regarding QM that still seems to sit on the sidelines waiting to be recognized (though I certainly don't claim to be the only one that recognizes it). Let's assume for one minute that the many worlds theory of quantum mechanics is true. Let's say that for every possible interaction at the molecular level, all possible interactions actually occur and the world splits off into multiple worlds on another dimension. The first point to make is that this theory is completely deterministic in the sense that all possible futures exist as a function of a past event. This is an important point. In the many worlds theory, we have all possible worlds existing at the same time, and the sum of all these worlds is deterministic, not random at all. The second point then, and the biggest question of all is that if all these worlds actually exist, why are we only conscious of a single world? Is there a mechanism or law of nature that results in our being aware of only a single world?