Following on from the last post, I want to talk about determinism. This is a companion concept to reductionism, whereby if you know the initial state of the big bang and all the fundamental equations on particle movement and interactions, you can in theory predict anything and everything in the universe, as a sequence of cause-and-effect. Of course, ever being able to gather all the required data to do that is, let's say, highly doubtful, let alone the considerations of actual modelling and computation. Nevertheless, if everything happens according to purely physical principles then everything in the future is already determined by what currently is which itself was determined by what was before etc.
Taken to it's ultimate conclusion this stipulates that the concept of free will is a false one, because your actions are entirely predictable as an effect of the chemical processes in your brain which are predictable as an effect of genetic evolution which is predictable as an effect of…etc etc. It would suggest that, for example, the political future of the planet is already fixed. Certain people will react in certain ways to certain events. My writing this blog post is inevitable as is your reaction to it (whatever that may be).
Quantum theory, according to Deutsch, undoes determinism by treating the most fundamental particle interactions as being unpredictable. While he doesn't explicitly state it, the implication seems to be that this is because those interactions are intrinsically random. However, this randomness is spread over an infinite number of universes, resulting in every possible outcome of those interactions taking place somewhere in the multiverse.
Essentially, instead of being determined to follow a particular path, we are instead determined to follow every path. For some reason, Deutsch thinks this constitutes free will. I fail to see how as actions are still physically determined, even if the base interactions that determine them are random. The random interaction (the big money question being what makes it random) determines the person's action in one universe. It also does so in another, just with a different result. Unless you can somehow control the random bit, you're stuck. If you can control it, it's not really random is it? 😉
Up next: The meaning of why.
This isn't strictly about the book but rather about how a misunderstanding of a common word greatly influences the science vs religion flame wars.