hypnagogue said:
What do you count as 'knowledge of reality'? Or more generally, what counts as 'knowledge'? Can it be purely computational in nature? Must it be mental? If so, must it be an object of experiential consciousness? Does sensory experience count?
Lots of good questions; I will address them in a different order:
What counts as 'knowledge': your perception that this question must be answered is actually part of the problem. We cannot know what 'knowledge' is. We have to acquire knowledge about things without knowing what knowledge is, yet we have been quite successful at that. That is only possible because the answer to the question "what is knowledge" is irrelevant.
Can it be purely computational in nature?: it follows from the above that this question is also unanswerable and irrelevant.
Must it be mental?: OK, now we start the process of lifting ourselves by pulling our shoelaces. Is knowledge mental? If we say it is, we imply that wherever you find knowledge you will also find a mind. If we say it isn't, then we imply it's possible for knowledge to exist completely by itself, with no relation to anything else - sort of "floating in nothingness", if that gives you the picture. Now exactly what is the difference between the two scenarios? The fact is, we can say "knowledge is mental", or we can say "knowledge is not mental", it doesn't matter. What matters is, if we say "knowledge is mental", then we cannot accept as true any assertion that implies that knowledge is non-mental. And vice-versa.
If so, must it be an object of experiential consciousness?: same scenario as before. Taking "knowledge is mental" as a premise leaves open the possibility of it being an object of experience, or not. As you duly noted. Again, it's your choice. Only be careful; as you make more choices, maintaining consistency between them becomes increasingly difficult.
Does sensory experience count [as knowledge]:? again, a matter of choice.
The challenge is not to find the answers to those questions, for they are nowhere to be found. The challenge is to make up answers that do not contradict each other. I can now answer your first question:
What do you count as 'knowledge of reality'?: nothing.
Now I need to explain what I just said in light of everything I said until that point. I'm trying to build a self-consistent abstract model of everything I know about everything. I take it as a premise that "reality cannot be known", and try to make all my knowledge consistent with that premise. You may choose differently; you may take "reality can be known" as a premise, but my experience tells me the task of keeping all your knowledge consistent with that premise to be incredibly difficult, perhaps impossible. To start with, given that in your model your conscious mind is separated from everything else in existence, you will have a heck of a hard time understanding how you can know anything at all about anything that exists (other than your conscious mind). That is actually called "the problem of solipsism", and last time I checked it had not been solved.
So you believe that physical laws are tautological, or necessary?
I don't believe in physical laws! From my perspective, the perception that the universe is ruled by laws is an illusion. Not a sensory illusion, just a cognitive one, like the ancient Egyptians who perceived the world as being ruled by the movement of celestial bodies.
How that illusion comes about is actually a very simple process. We come up with "physical laws" which supposedly allow us to predict the behavior of matter, but anyone knows that the behavior of matter is, far more often than not, extremely unpredictable. So how do we reconcile our belief in those physical laws with our inability to apply them except in extremely restricted scenarios? Simple: we come up with more "physical laws" which explain why our predictions fail. "It's there but we cannot see/measure it" kind of thing.
Again, that seems like a valid position but it's a very hard one to sustain on an intellectual level.
Given what we know, it seems they just as well could be contingent, i.e. possibly different in different universes.
It seems that way, but it isn't. You think it's possible for a universe to exist without quantum mechanics or relativity, but if you examine it more closely, you'll realize the notion is erroneous. Our science is not a description of our universe, it's a description of our point of view. The laws of physics are statements about our way of thinking about the abstract concept called "universe", not about whatever it is the concept refers to. So for as long as you remain rational, you will perceive any universe the same way: as a collection of objects moving through space and time. And when you stop being rational, then even the concept "universe" ceases to exist for you.
And if they are contingent, then by your claim we shouldn't be able to know anything about them.
Well, I think the particular features of our universe are contingent, in the sense that I can think of a universe without stars, planets, organic matter, and so on. But the particular features of our universe are not contingent on logic or anything derived from it (ie, science). For as long as a universe has space, time, and matter, it can be described with current physics. And if it doesn't have space, time, or matter, then it's not a universe to begin with.