They aren't quite interchangeable but they are closely related.
It spins on the difference between material and physical. "Materialism" really responds to an older view - the newtonian one and maybe also the relativistic one. In this case, materialistic and deterministic are interchangeable.
That sort of materialism implies determinism.
So what is the point of even using a term that has been overtaken by scientific knowledge?
Only QM changes the picture. But if you introduce QM and call QM "a purely physical
theory" then you are introducing the inherent acausality of QM into your notion of physical and physicalism. At this point, free will is not incompatible with the laws of physics, because the laws of physics have expanded enough to encompass acausality. That help?
I don't think there is a notion of physical. It is something that will change as we discover new things. It certainly changed a lot in the last century. I looks like the notion of physical will change a lot this century too.
The problem is not that free will is incompatible with the laws of physics. The problem is that free will has no intelligible definition. The physics or even metaphysics are irrelevant, nobody has proposed what ~determinate && ~arbitrary means.
QM may allow for randomness, but it does not allow for something which is not determinate and also not random. That idea still does not make sense.
That's still being argued about.
But what is not argued is that if it turns out that real randomness exists, then real randomness will be part of physics. Nobody has ever suggested that there is some area of reality where physicists will simply throw up their hands and say "not our department".
....or acausal free will or fate/karma.......
It does not matter what you call it, if it is not determined and not arbitrary, what is it?
Giving it a name does not help.
Sure, without some degree of determinism, free will couldn't operate. There is an analogy available with a car. Free will is like your hands on the driving wheel. But without the rigid deterministic mechanisms inside the body of the car, your attempts to impose your free will on the movement of the car would fail. You need the car to behave deterministically in order to be able to drive the car. Now just think of the your body as an extension of the car and the thing doing the driving to be your "I".
That is merely to push the problem further back. Without some degree of determinism your driver could not work. Then without some degree of determinism your "I" could not work.
You must finally address the problem that when you have sorted out all the determinate parts and distil a - something - an entity or a principle - that is purely indeterminate.
So if the purely indeterminate is not arbitrary, then what is it?
It wasn't nonsense. Multiverse theory is proposed because otherwise you have to explain why the cosmological constants look fine-tuned for life. If there are lots and lots of Universes, it ceases to be a problem. It's a metaphysical answer. Not an empirical one.
Let's get this clear. Multiverse theory is proposed because the maths in String Theory suggests that there are many universes.
That makes it empirical, not metaphysical.
Originally it was believed that the maths was simply wrong or incomplete, but others have suggested that in fact the maths is right and there are many universes.
Some debate about the anthropic principle has arisen from the mathematical problem, but it would have never been proposed if the maths did not suggest it in the first place.
