[Once again, I’ve been inspired by a post on Albert Wenger’s blog, this time about whether or not free will exists.]
I’ve spent a long time thinking about this one as well. I think you’re probably right, but here’s the best alternative I’ve been able to come up with. These ideas are heavily inspired by having finally finished Gödel, Escher, Bach.
Basically, it’s clearly true that determinism holds over the space of physical objects if you assume that a continuous set of physical laws governs all physical interactions. If my brain is just a physical object, then the arrangement of its atoms at present is exclusively a function of their arrangement in the past.
But how justified are we in making that assumption about the continuity and coverage of physical laws?
Let’s start with coverage: it’s actually not hard to think of something that doesn’t interact with the physical world in quite the same way as an apple – a computer program.
Yes, a program is represented by marks on a disk, and yes it is executed by a set of magnets that write and erase those marks using electricity routed through a CPU. But ultimately those purely physical components produce an informational state projected through my screen. And as I write I am interacting not only with the keys of my keyboard but also but with the abstract state of the system. And the state per se has causal power: perform a Caesar cipher on your blog post and it becomes virtually meaningless to me despite having extremely similar statistical properties and on-disk representation.
So then where does the meaningfulness of the program state reside? Can we point to a memory address that distinguishes “meaningful” from not meaningful (even in principle)? Can we point to an atom in my brain that makes the text meaningful to me, even though it would remain meaningful to you even if my brain we destroyed (and vice versa) but become meaningless if all brains were destroyed?
The point here is that even in closed physical systems, there is an information “layer” that has both its own rules (i.e. “logic”) and yet tangibly influences the physical world. This is the layer where the program-ness of a program resides, or the law-ness of physical laws, or the meaningful-ness of a sentence.
Normally this layer is well behaved – I encode my experiences into words that you understand; when fundamental particles interact they “check” which laws to follow and then they follow them.
But the layer has known flaws, specifically when self-reference enters the picture. Gödel’s incompleteness theorem establishes that there are questions which can be precisely formulated but not decided, e.g whether the statement “this statement is a lie” is true or not (or the somewhat related question of whether an arbitrary computer program will ever terminate.) These questions aren’t undecidable because of a deficit in our ability to measure (a la Heisenberg uncertainty) but rather because of an irresolvable quirk in the laws of the information layer.
The interesting thing about consciousness (the domain within which free will would presumably operate) is that it is deeply and inherently self-referential. The very exercise of writing this comment is an example of an information state reflecting on its own statefulness.
Now let’s circle back to the question of consistency in physical laws. Usually it seems like the surest bet: no one has ever been fired for predicting that an apple will obey gravity.
But when we start talking about the way that particles in our brain interact with the information layer (in ways we understand only loosely, at best) and we focus in on an area (self-reference) where the information layer is already know to misbehave, how confident can we be that the rules we’ve observed elsewhere operate the same way here?
Or more colorfully, how certain can we free will isn’t some sort of buffer overflow in the operating system of the universe?