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thomblake comments on The Fabric of Real Things - Less Wrong
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I am confused by these posts. On one hand, Eliezer argues for an account of causality in terms of probability, which as we know are subjective degrees of belief. So we should be able to read off whether X thinks A causes B from looking at conditional probabilities in X's map.
But on the other hand, he suggests (not completely sure this is his view from the article) that the universe is actually made of cause and effect. I would think that the former argument instead suggests causality is "subjectively objective". Just as with probability, causality is fundamentally an epistemic relation between me and the universe, despite the fact that there can be widespread agreement on whether A causes B. Of course, I can't avoid cancer by deciding "smoking doesn't cause cancer", just as I can't win the lottery by deciding that my probability of winning it is .9.
For instance, how would an omniscient agent decide if A causes B according Eliezer's account of Pearl? I don't think they would be able to, except maybe in cases where they could count frequencies as a substitute for using probabilities.
An omniscient agent would have no reason to decide if A causes B, since causality is a tool for predicting the outcomes of interventions, and the omniscient agent already knows what's going to happen. The concept of "causality" is only useful from a perspective of limited knowledge, much like probability. And the concept of an "intervention" only makes sense in a level of abstraction where free will is apparent.
Pearl addresses this in slide 47 of this lecture. Causality disappears if you consider the entire universe as your object of investigation.
I think Bundle's question is just that, given the above, how can Eliezer also say that the universe is actually made of cause and effect?
Does Eliezer say that the universe is actually made of cause and effect? Also, what work is "actually" doing in that sentence?
"Actually" isn't intended in any sense except emphasis and to express that Eliezer's view is contrary to my expectations (for instance, "I thought it was a worm, but it was actually a small snake").
Eliezer does seem to be endorsing the statement that "everything is made of causes and effects", but I am unsure of his exact position. The maximalist interpretation of this would be, "in the correct complete theory of everything, I expect that causation will be basic, one of the things to which other laws are reduced. It will not be the case that causation is explained in terms of laws that make no mention of causation". This view I strongly disagree with, not least because I generally think something has gone wrong with one's philosophy if it predicts something about fundamental physics (like Kant's a priori deduction that the universe is Euclidean).
I suspect this is not Eliezer's position, though I am unsure because of his "Timeless Physics" post, which I disagree with (as I lean towards four-dimensionalism) but which seems consonant with the above position in that both are consistent with time being non-fundamental. If he means something weaker, though, I don't know what it is.
Yes, I think Timeless Physics puts you on the right track, and it should be pretty clear that "causality" doesn't apply so much at the level of comparing possible states of configuration space, aside from perhaps metaphorically to point to which ones are adjacent to which other ones.
Well, if I may take up Bundle's question on his behalf, Eliezer said, in the article to which these are comments:
and
Where I take the second quote to imply an endorsement on Eliezer's part of the claim 'everything is made of causes and effects'.
I don't know, I was quoting (without making that clear) Bundle's phrase.
That was from a koan, and a good one at that. How would one perform an experiment to determine whether the universe operates on causes and effects? It suggests there might be something wrong with the conception that the universe is "made of" causes and effects.
Maybe, though given the introduction to the article, I think the koan is about the question 'what counts as meaningful?', not 'is the universe made of causal relations'.
But, perhaps more interesting than settling the question of whether or not Eliezer thinks the universe is made of causal relations, we can ask "Is the thesis that the universe is made of causal relations inconsistant with Eliezer's (and your) views on the objectivity of causal relations?'
Given your responses, my dialectical instincts are telling me you think the answer to the above is 'Yes, they are inconsistant, and it is false that the universe is made of causal relations'. Is that so?
Yes. I thought I actually made that explicit. At least, it's not "made of" causal relations any more than it's "made of" probability.
Thanks. I think Eliezer is endorsing the 'causal relations are fundamental' reading, and that this apparently conflicts with the idea that causality is the tool of a limited observer. I think he's likely to see these as reconcilable in some way. That, at any rate, is my prediction.
My prediction is that he never noticed this problem before.