Look, I reckon the issues that you raise here are real and good to ponder about. It’s true that FDT is about intervening on logical dependency graphs and it’s unclear foundationally how we ought to go about constructing logical dependency graphs.
But almost the same thing is true for causal dependency graphs. Pearl’s definitions of causality are ultimately fairly circular. What is an intervention, platonically? Not as a sort of practical “how do you go and simulate an intervention in an experiment?”, but what fundamentally is this intervention thing we’re trying to approximate? And the answer is, it’s the thing that makes the resulting distribution match the true causal graph. In Pearl’s words, the true interventions are conducted “on God’s computer”. God’s computer here being precisely the platonically ideal causal graph. Okay, great. So then what’s the correct causal graph; how do we determine the program on God’s computer? Well, the correct causal graph is the one gives us the right consequences of interventions. So this is circular. I don’t think the non-Pearlean alternatives are better; I think they’re worse.
One objection here might go like: sure we don’t know really how causal dependency graphs are founded, but we know we can’t construct logical dependency graphs of the type we need, so we have a stronger objection to FDT. And..maybe, but I still think informal FDT has some advantages over informal CDT.
I might cheekily characterize FDT versus CDT like this: CDT is what you get when you go and try and model your situation while whispering the word “causal” in the back of your mind while FDT is what you get when you go and try and model your situation while whispering the word “logical” in the back of your mind. And I think FDT might genuinely win this one. If your logical vibes coincide with your causal vibes, then there’s no problem. Where they come apart, like in Newcombe’s problem, the FDT vibes are better.
Now you might say, in the smoking lesion, where do the logical vibes push me? Here, I happen to agree with you that the answer is unclear, I don’t think they clearly agree with the causal vibes. But I can’t chalk this up as a win for CDT. If I make the problem precise in such a way that the CDT answer is clearly intuitively correct (e.g. no one else has thought through the decision theory of this problem yet, so my doing so puts them outside my reference class), then I think the logical vibes and causal vibes do agree. In other cases—all the other people truly are in my reference class—then I’m not sure that the causal recommendation is appropriate.
A more specific criticism is that the kind of dependency that CDT says is the correct one to evaluate does not itself depend on any deeper justification. It’s just that intuitively, causal-vibe dependencies are usually the ones we want to track. But, while intuition is a good guide as to what we should do in typical cases, it is a poor guide as to what we should choose in unusual cases. So I don’t see much reason to presume in favour of CDT here.
I am aware that I am somewhat outlier-skeptical of causation with respect to most philosophers, but I am prepared to defend this position.
Look, I reckon the issues that you raise here are real and good to ponder about. It’s true that FDT is about intervening on logical dependency graphs and it’s unclear foundationally how we ought to go about constructing logical dependency graphs.
But almost the same thing is true for causal dependency graphs. Pearl’s definitions of causality are ultimately fairly circular. What is an intervention, platonically? Not as a sort of practical “how do you go and simulate an intervention in an experiment?”, but what fundamentally is this intervention thing we’re trying to approximate? And the answer is, it’s the thing that makes the resulting distribution match the true causal graph. In Pearl’s words, the true interventions are conducted “on God’s computer”. God’s computer here being precisely the platonically ideal causal graph. Okay, great. So then what’s the correct causal graph; how do we determine the program on God’s computer? Well, the correct causal graph is the one gives us the right consequences of interventions. So this is circular. I don’t think the non-Pearlean alternatives are better; I think they’re worse.
One objection here might go like: sure we don’t know really how causal dependency graphs are founded, but we know we can’t construct logical dependency graphs of the type we need, so we have a stronger objection to FDT. And..maybe, but I still think informal FDT has some advantages over informal CDT.
I might cheekily characterize FDT versus CDT like this: CDT is what you get when you go and try and model your situation while whispering the word “causal” in the back of your mind while FDT is what you get when you go and try and model your situation while whispering the word “logical” in the back of your mind. And I think FDT might genuinely win this one. If your logical vibes coincide with your causal vibes, then there’s no problem. Where they come apart, like in Newcombe’s problem, the FDT vibes are better.
Now you might say, in the smoking lesion, where do the logical vibes push me? Here, I happen to agree with you that the answer is unclear, I don’t think they clearly agree with the causal vibes. But I can’t chalk this up as a win for CDT. If I make the problem precise in such a way that the CDT answer is clearly intuitively correct (e.g. no one else has thought through the decision theory of this problem yet, so my doing so puts them outside my reference class), then I think the logical vibes and causal vibes do agree. In other cases—all the other people truly are in my reference class—then I’m not sure that the causal recommendation is appropriate.
A more specific criticism is that the kind of dependency that CDT says is the correct one to evaluate does not itself depend on any deeper justification. It’s just that intuitively, causal-vibe dependencies are usually the ones we want to track. But, while intuition is a good guide as to what we should do in typical cases, it is a poor guide as to what we should choose in unusual cases. So I don’t see much reason to presume in favour of CDT here.
I am aware that I am somewhat outlier-skeptical of causation with respect to most philosophers, but I am prepared to defend this position.
Note that BB approvingly quotes Schwarz, who thinks that other formulations of CDT by Lewis, Joyce, or Skyrms are better than Pearl’s.