Hmm, re-reading Timeless Causality, I don’t see how I could have learned that the idea belongs to Barbour and that you disagree with him. It sure sounds like it was your idea.
This sounds like a high-priority problem, but actually I don’t see any reference to reduction-to-similarity in Timeless Causality, although there’s a lot in Barbour’s book about it. What do you mean by “mind reduces to computation which reduces to causal arrows which reduces to some sort of similarity relationship between configurations”? Unless this is just in the sense that causal mechanisms are logical relations?
I interpreted this paragraph as sugesting that causality reduces to similarity, but given your latest clarifications, I guess what you actually had in mind was that causality tends to produce similarity and so we can infer causality from similarity.
When two regions of spacetime are timelike separated, we cannot deduce any direction of causality from similarities between them; they could be similar because one is cause and one is effect, or vice versa. But when two regions of spacetime are spacelike separated, and far enough apart that they have no common causal ancestry assuming one direction of physical causality, but would have common causal ancestry assuming a different direction of physical causality, then similarity between them… is at least highly suggestive.
Previously, I thought you considered causality to be a higher level concept rather than a primitive one, similar to “sound waves” or “speech” as opposed to say “particle movements”. That sort of made sense except that I didn’t know why you wanted to make causality an integral part of decision theory. Now you’re saying that you consider causality to be primitive and a special kind of logical relations, which actually makes less sense to me, and still doesn’t explain why you want to make causality an integral part of decision theory. It makes less sense because if we consider the laws of physics as logical relations, they don’t have a direction. As you said, “Time-symmetrical laws of physics didn’t seem to leave room for asymmetrical causality.” I don’t see how you get around this problem if you take causality to be primitive. But the bigger problem is that (at the risk of repeating myself too many times) I don’t understand your motivation for studying causality, because if I did I’d probably spend more time thinking about it mysef and understand your ideas about it better.
I’m trying to think like reality. If causality isn’t a special kind of logic, why is everything in the known universe made out of (a continuous analogue of) causality instead of logic in general? Why not Time-Turners or a zillion other possibilities?
If causality isn’t a special kind of logic, why is everything in the known universe made out of (a continuous analogue of) causality instead of logic in general?
Wait, if causality is a special kind of logic, how does that help answer the question? Don’t we still have to answer why the universe is made of this kind of logical instead of some other?
Why not Time-Turners or a zillion other possibilities?
I don’t understand how lack of Time-Turners makes you think causality is a special kind of logic or why you want to incorporate causality into decision theory (which is still my bigger question). Similar questions could be asked about other features of the universe:
Why does the universe have 3 spatial dimensions instead of a zillion other possibilities?
Why doesn’t the laws of physics allow information to be destroyed (i.e., never maps 2 different states at time t to the same state at time t+1)?
But we’re not concerned about these questions at the level of decision theory, since it seems possible to have a decision theory that works with an arbitrary number of dimensions, and with both kinds of laws of physics. Similarly, I don’t see why we can’t have a “causality-agnostic” decision theory that works in universes both with and without Time-Turners.
I think the point was more about whether causality should be thought of as a fundamental part of the rules, like this, or whether it’s more useful to think of causality as an abstraction that (ahem, excuse the term) “emerges” from the fundamentals when we try to identify patterns in said fundamentals.
Somewhat akin to how “meaning” exists in a computer program despite none of the bits fundamentally meaning anything, I think. My thoughts are becoming more and more confused as I type, though, which makes me wish I had an environment suitable to better concentration.
This sounds like a high-priority problem, but actually I don’t see any reference to reduction-to-similarity in Timeless Causality, although there’s a lot in Barbour’s book about it. What do you mean by “mind reduces to computation which reduces to causal arrows which reduces to some sort of similarity relationship between configurations”? Unless this is just in the sense that causal mechanisms are logical relations?
I interpreted this paragraph as sugesting that causality reduces to similarity, but given your latest clarifications, I guess what you actually had in mind was that causality tends to produce similarity and so we can infer causality from similarity.
Previously, I thought you considered causality to be a higher level concept rather than a primitive one, similar to “sound waves” or “speech” as opposed to say “particle movements”. That sort of made sense except that I didn’t know why you wanted to make causality an integral part of decision theory. Now you’re saying that you consider causality to be primitive and a special kind of logical relations, which actually makes less sense to me, and still doesn’t explain why you want to make causality an integral part of decision theory. It makes less sense because if we consider the laws of physics as logical relations, they don’t have a direction. As you said, “Time-symmetrical laws of physics didn’t seem to leave room for asymmetrical causality.” I don’t see how you get around this problem if you take causality to be primitive. But the bigger problem is that (at the risk of repeating myself too many times) I don’t understand your motivation for studying causality, because if I did I’d probably spend more time thinking about it mysef and understand your ideas about it better.
I’m trying to think like reality. If causality isn’t a special kind of logic, why is everything in the known universe made out of (a continuous analogue of) causality instead of logic in general? Why not Time-Turners or a zillion other possibilities?
Wait, if causality is a special kind of logic, how does that help answer the question? Don’t we still have to answer why the universe is made of this kind of logical instead of some other?
I don’t understand how lack of Time-Turners makes you think causality is a special kind of logic or why you want to incorporate causality into decision theory (which is still my bigger question). Similar questions could be asked about other features of the universe:
Why does the universe have 3 spatial dimensions instead of a zillion other possibilities?
Why doesn’t the laws of physics allow information to be destroyed (i.e., never maps 2 different states at time t to the same state at time t+1)?
But we’re not concerned about these questions at the level of decision theory, since it seems possible to have a decision theory that works with an arbitrary number of dimensions, and with both kinds of laws of physics. Similarly, I don’t see why we can’t have a “causality-agnostic” decision theory that works in universes both with and without Time-Turners.
I think the point was more about whether causality should be thought of as a fundamental part of the rules, like this, or whether it’s more useful to think of causality as an abstraction that (ahem, excuse the term) “emerges” from the fundamentals when we try to identify patterns in said fundamentals.
Somewhat akin to how “meaning” exists in a computer program despite none of the bits fundamentally meaning anything, I think. My thoughts are becoming more and more confused as I type, though, which makes me wish I had an environment suitable to better concentration.