Revisiting Quantum Mechanics and Free Will

In my last post, I made some rather broad claims regarding the nature of the universe and determinism.  I'd like to go into a little bit of that more deeply.

From Quantum Mechanics, we know that with all of the smallest particles, we cannot determine their location and velocity exactly. Instead, we can only say with what probability they will be in a location or have such a velocity.

For the purposes of this argument, let's presuppose that there are no hidden variables that determine location that we can't identify. Instead, let's assume at the most basic level, this universe is inherently probilistic.

Now, let's recover Laplace's Demon.  Remember that the demon is defined as some extra-universal entity which has perfect knowledge of every particle in the universe at a single moment in time. Also, the demon has unlimited computing power and our current level of knowledge of quantum mechanics.

In this case, the Demon cannot say what the universe will look like in the next period of time.  Instead, he can calculate all of the infinitely possible next states of the universe, and the probablitity of each of them occurring.  Now suppose that he calculates the next states of the universe from that set of states, and so on until the end of time.  Here is the essential question: can anything happen in the universe that would not appear in the Demon's model of the universe?

I do not see how it could.  But how does this apply to Free Will?

Let us suppose that our theory of the mind is physicalism and functionalism (note: they are not mutually exclusive).  Physicalism is the philosophy that only physical things exist. In Philosophy of Mind, it states that a mind is a physical thing in all aspects.  For humans, this means that a mind is solely the brain and whatever other neural connections attached to it.  Functionalism is the idea that minds are defined by their functional roles, e.g. if some computer's circuitry mimics human vision processing perfectly, on a mental level, there is no way to distinguish the two.

From these definitions and my previous assertion that only things calculated by my expanded Laplace's Demon can happen in this universe, the only viable conclusion is that every mental action, every thought, can be predicted by the Demon.  Which means everything is determined, free will cannot exist.

When I say "free will,"I mean the ability to make choices free from constraints.  But since all mental thoughts are constrained by the physical, and the physical is determined (or at the very least, predictable, which amounts to the same thing), then our entire mental lives are determined.

Of course, Laplace's Demon cannot exist due to the boundary constraints of the universe.  Quite simply, any machine with its predictive power would require more particles than the entire universe and it would take longer to compute than the age of the universe.

Yes, Zach Weiner not only can make the same argument I can in a more concise form, but can also make it into a sex joke at the same time.  Go read his comic. SMBC-Comics.com

Free will could only exist if mental activity was immaterial or in a separate universe from this one where physics works differently.  To illustrate this concept, imagine a game of World of Warcraft. Even if you knew the entire programming code of the game, you would not be able to predict the actions of the players' avatars because their actions are dependent on what the players do, and the players are entities not described or constrained by the programming.

So should we check out now because everything that can happen, will happen, and that's that?  Not quite.  Because we know that Laplace's Demon cannot exist, any predictive models we develop will have a certain inherent inaccuracy.  To extend the metaphor used above, even if our model is the game's programming, there are still the elements(the players at home) that we can't know.

This means that when we construct models on decision making and behavior (and from that, some of cognitive science, all of economics, and all of political philosophy),  we need to try to account for as man variables as possible while still acknowledging that there are errors being made.  We need to assume everyone has free will while simultaneously acknowledging that they don't.

Due to the obvious contradiction above, I foresee numerous debates involving which variables can be accurately measured and predicted (and with what precision and accuracy), and from those debates, the relative strengths and weaknesses of different models. However, as long as everyone involved in those debates is relying on this same philosophical framework, I think the disagreements that will arise can be handled amicably and with careful acknowledgement of where the differing viewpoints come from.

Hopefully, these past two posts help place all of my other posts in a more understandable framework, and my intention is for all claims I make on this blog in regards to economics and political philosophy to be in basic accordance with this structure.