I don’t see how reality of physics is used in your reasoning. I did see that you claim that you do use it, and that you mentioned it in the posts, but I don’t see how it’s doing some work in some argument. I don’t see how humanity accomplishing incredible things has anything to do with the world being real, we could similarly accomplish incredible things in a world that isn’t real.
My frame is grounded in thinking about decision theory, where one thing that keeps coming up is counterfactuals, reasoning about what would happen under conditions that at some point are revealed to in fact fail to hold. This is reasoning about situations and worlds that are not real, and for this form of decision making to make sense, it’s necessary for the reasoning about worlds that are not real to reach meaningful conclusions. This makes discussion of detailed claims about worlds that are not real a normal thing, not something strange. And when that crystallizes into an intuitive way of looking at things in general, it becomes apparent that if our physical world wasn’t real in a similar sense, literally nothing about anything would change as a result. Relevance of the world being real is largely an illusion.
What matters about the world being real is that it seems to be the case that we care about what happens in the physical world, possibly more than about what happens in some other hypothetical worlds. That’s a formulation of the meaning of the physical world being real that’s more clear to me than how these words are normally used (i.e. without a satisfactory clarification or an argument for truth of the claim that might also serve that purpose).
I completely agree that reasoning about worlds that do not exist reaches meaningful conclusions, though my view classifies that as a physical fact (since we produce a description of that nonexistent world inside our brains, and this description is itself physical).
it becomes apparent that if our physical world wasn’t real in a similar sense, literally nothing about anything would change as a result.
It seems to me like if every possible world is equally not real, then expecting a pink elephant to appear next to me after I submit this post seems just as justified as any other expectation, because there are possible worlds where it happens, and ones where it doesn’t. But I have high confidence that no pink elephant will appear, and this is not because I care more about worlds where pink elephants don’t appear, but because nothing like that has ever happened before, so my priors that it will happen are low.
For this reason I don’t think I agree that nothing would change if the physical world wasn’t real in a similar sense as hypothetical ones.
What I mean by reaching meaningful conclusions about counterfactuals is that you start with a problem statement, a description of a possibly counterfactual situation, and then you see what follows from that. You don’t get to decide that pink elephants follow just because the situation is counterfactual, any pink elephants would need to follow from the particular problem statement that you start with. Existence of other counterfactuals (other possible worlds) with pink elephants is completely irrelevant, because we are not reasoning about them at the moment.
Similarly, if you reason about the physical world that isn’t real, it doesn’t matter that there are other alternative physical worlds that are also not real with different properties, because we are reasoning about this particular not-real world, not those other ones. The problem statement constrains the expectations, not reality of the thing referenced by the problem statement.
I don’t see how reality of physics is used in your reasoning. I did see that you claim that you do use it, and that you mentioned it in the posts, but I don’t see how it’s doing some work in some argument. I don’t see how humanity accomplishing incredible things has anything to do with the world being real, we could similarly accomplish incredible things in a world that isn’t real.
My frame is grounded in thinking about decision theory, where one thing that keeps coming up is counterfactuals, reasoning about what would happen under conditions that at some point are revealed to in fact fail to hold. This is reasoning about situations and worlds that are not real, and for this form of decision making to make sense, it’s necessary for the reasoning about worlds that are not real to reach meaningful conclusions. This makes discussion of detailed claims about worlds that are not real a normal thing, not something strange. And when that crystallizes into an intuitive way of looking at things in general, it becomes apparent that if our physical world wasn’t real in a similar sense, literally nothing about anything would change as a result. Relevance of the world being real is largely an illusion.
What matters about the world being real is that it seems to be the case that we care about what happens in the physical world, possibly more than about what happens in some other hypothetical worlds. That’s a formulation of the meaning of the physical world being real that’s more clear to me than how these words are normally used (i.e. without a satisfactory clarification or an argument for truth of the claim that might also serve that purpose).
I completely agree that reasoning about worlds that do not exist reaches meaningful conclusions, though my view classifies that as a physical fact (since we produce a description of that nonexistent world inside our brains, and this description is itself physical).
It seems to me like if every possible world is equally not real, then expecting a pink elephant to appear next to me after I submit this post seems just as justified as any other expectation, because there are possible worlds where it happens, and ones where it doesn’t. But I have high confidence that no pink elephant will appear, and this is not because I care more about worlds where pink elephants don’t appear, but because nothing like that has ever happened before, so my priors that it will happen are low.
For this reason I don’t think I agree that nothing would change if the physical world wasn’t real in a similar sense as hypothetical ones.
What I mean by reaching meaningful conclusions about counterfactuals is that you start with a problem statement, a description of a possibly counterfactual situation, and then you see what follows from that. You don’t get to decide that pink elephants follow just because the situation is counterfactual, any pink elephants would need to follow from the particular problem statement that you start with. Existence of other counterfactuals (other possible worlds) with pink elephants is completely irrelevant, because we are not reasoning about them at the moment.
Similarly, if you reason about the physical world that isn’t real, it doesn’t matter that there are other alternative physical worlds that are also not real with different properties, because we are reasoning about this particular not-real world, not those other ones. The problem statement constrains the expectations, not reality of the thing referenced by the problem statement.