As some of you know, I’ve recently been working in a medical lab doing computational medicine/neuroscience work. Specifically, I’m working on:
- A study on optimal vaccine distribution
- A study on brain modelling <---- this is the one of interest for this
- A study on machine learning in medical education
I’ve been work on that middle study for about a year, and I recently got a couple of interesting results. One of them is a model for predicting (or inferring) brain activity states from a sequence of brain activity states. Being a model this is, of course, an abstraction. I am not simulating all of the hundreds of billions of neurons in the brain, and all of the connections. Without getting too much into the technical details, I’m using graphs that have self-contained modification rules.
Our initial experiment was to use deterministic rules only. This was not very successful.
So we added stochastic rules (rules with an associated probability). This means that it is only possible to predict either the most probable next brain state or predict some set of brain states with associated probabilities of occurring.
When we changed to stochastic rules, the accuracy went up considerably. Currently, it is about 60% accurate at predicting the next most likely brain state.
Now, the intent of this research has nothing to do with free will. Rather the next steps are to further improve accuracy, and see if there are transition patterns that would allow us to recognize a neurological injury, disease, or the state (at rest, overloaded, etc.). Wonderful.
But it did get me thinking about free will. Any time you have a stochastic model, the obvious question is whether the underlying process being modeled is, in fact, stochastic, or is there some information that is missing that would allow for a deterministic model to be produced.
Suppose we find a fully deterministic model with 100% accuracy. Would you take this as evidence against free will? It seems to me like a deterministic model with 100% accuracy has to imply that there is no free will. … Except there’s always that little bit of wiggle room coming from the models having some layers of abstraction.
Consider now the stochastic model. Suppose the accuracy is improved such that the next most probable brain state matches the actual brain state with some percentage x. (Let’s say x=95%, but you can pick whatever you wish). And furthermore, suppose that in the remaining cases, the brain is always within the top N predicted states (again, you can pick N to be whatever you like). The point is suppose that the model has, with these conditions, 100% accuracy. Would you consider this to be evidence for or against free will?
Consider now our existing stochastic model with an accuracy of about 60% at predicting the next brain state with a certain probability. Do you consider this to be evidence for or against free will?
Let’s just generalize, what sort of scientific evidence would you consider definitive or at least extremely compelling with respect to the existence of non-existence of free will? The non-existence of free will has the misfortune of being on the trying to prove a negative, so we’ll only hold it to the standard of extremely compelling.
FYI, I believe in free will. I have no real evidence for this other than my own experiences and observations of the universe. When I see the universe, I do not see something that is driven purely by the inevitableness from an initial physical state. I believe that we have a soul/spark/whatever that allows us some control over the mechanisms of our thinking. I’m not necessarily trying to (or going to try to) convince anyone I’m correct, I’m just stating what I think to provide context to the post.
Note, to any mods, I fully expect that this thread will descend into a more general free will debate. I’m ok with that. There’s no need (from my point of view) to call any such discussion as a hijack.