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A Philosopher Reviews Judea Pearl's “The Book of Why”

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Re: A Philosopher Reviews Judea Pearl's “The Book of Why”

#31
I mostly agree with Pearl.

However, the account of traditional statistics given in this article is misleading. Randomisation is a major part of traditional stats, and it is inherently a causal hypothesis: breaking the links between unobserved covariates and treatment regimes.

An important alternate contemporary causal inference framework by Rubin has origins in a 1923 thesis...

...but the content of Pearl's approach seems superior; if you ignore the academic spats.

Re: A Philosopher Reviews Judea Pearl's “The Book of Why”

#32

> “but given my own background I could not but wonder how much farther Pearl would have gotten had he had the training I did as a philosopher.” The review had some good call outs but given the above quote and a few surrounding criticisms, this review is more pretentious than anything.

The reviewer is Tim Maudlin, one of the foremost philosophers of physics. It's kind of hard to find someone better placed than him to review a book about causality, and his comment seems entirely appropriate.

Re: A Philosopher Reviews Judea Pearl's “The Book of Why”

#33
post #6

I like the review, but the criticism of distinguishing causality from counterfactual reasoning feels weak to me. Do we actually care about the counterfactual reasoning most? Of course. But establishing causality as its own thing before counterfactuals is necessary in the way that Pearl has structured his math. And even the grammar of human languages enforces this separation of concepts. Do you need causality to even…

I am not sure how to define "cause" without introducing counterfactuals. "This happened because I did that" seems to imply "Had I not done that, this would not have happened" -- a counterfactual.

No, these two statements are not equivalent. Perhaps what you have in mind is the contrapositive "This didn't happen, so I didn't do it". More formally, A -> B is equivalent to -B -> -A, but it is not equivalent to -A -> -B.

Re: A Philosopher Reviews Judea Pearl's “The Book of Why”

#34
This presents the RCT criterion uncritically, albeit citing a case where it would be hard to apply.

But RCT fails -- gives a nonsense result -- when the hypothesis under test is incoherent. This wouldn't matter, except that RCT is routinely used in such circumstances, and the results treated as gospel by people in positions of authority.

Consider: Outcome X may have six causes A-F. RCT tests B, and finds that varying B only affects one in six cases. With infinitely many trials, the relationship resolves, but with one trial the difference is indistinguishable from noise.

Substitute a medical symptom for X, and a medical treatment that addresses one of six causes, for B. After one RCT, B is "shown" to be ineffective.

The problem is not B. The problem is that X is ill-defined. X could be a mental illness, or tumors in a given organ. How often do we read "anti-depressants shown ineffective"? The only way we have to distinguish one variety of depression from the next is which treatment works.

The problem is not limited to medicine.

Re: A Philosopher Reviews Judea Pearl's “The Book of Why”

#35
post #34

This presents the RCT criterion uncritically, albeit citing a case where it would be hard to apply. But RCT fails -- gives a nonsense result -- when the hypothesis under test is incoherent. This wouldn't matter, except that RCT is routinely used in such circumstances, and the results treated as gospel by people in positions of authority. Consider: Outcome X may have six causes A-F. RCT tests B, and finds that varying…

A nice point. But this is not a criticism of the RCT so much as a criticism of how its results are used or interpreted.

Re: A Philosopher Reviews Judea Pearl's “The Book of Why”

#36

I mostly agree with Pearl. However, the account of traditional statistics given in this article is misleading. Randomisation is a major part of traditional stats, and it is inherently a causal hypothesis: breaking the links between unobserved covariates and treatment regimes. An important alternate contemporary causal inference framework by Rubin has origins in a 1923 thesis... ...but the content of Pearl's approach…

>> Randomisation is a major part of traditional stats, and it is inherently a causal hypothesis

Yes, randomization is central to classical statistics, but no, it is not inherently causal. Drawing a random sample from a bivariate distribution (X,Y) is key to doing a lot (though not all) of classical statistical inference (think of estimating slopes in regression), but the randomization does not imply anything about the causal relationship between X and Y. When you speak of randomization in the context of "treatment regimes," you are thinking about randomized controlled trials, which the piece does analyze explicitly, in some detail. So in this sense the account given in the essay is not misleading.

Re: A Philosopher Reviews Judea Pearl's “The Book of Why”

#37
post #20

I’m 30 pages into the book. It hasn’t grabbed me yet. Worth finishing?

I read it in a beach in Greece. It really opened up some new thoughts to me that are relevant to some of the problems that I am thinking about in applying ML in science. It made me want to go back and read some of his more technical work. It's not the easiest of reading, but I definitely found it worthwhile!

Re: A Philosopher Reviews Judea Pearl's “The Book of Why”

#38

I mostly agree with Pearl. However, the account of traditional statistics given in this article is misleading. Randomisation is a major part of traditional stats, and it is inherently a causal hypothesis: breaking the links between unobserved covariates and treatment regimes. An important alternate contemporary causal inference framework by Rubin has origins in a 1923 thesis... ...but the content of Pearl's approach…

>> Randomisation is a major part of traditional stats, and it is inherently a causal hypothesis Yes, randomization is central to classical statistics, but no, it is not inherently causal. Drawing a random sample from a bivariate distribution (X,Y) is key to doing a lot (though not all) of classical statistical inference (think of estimating slopes in regression), but the randomization does not imply anything about th…

I'm afraid you're mistaken. Randomisation allows one to make the strong causal assumption that the treatment regime allocation is unrelated to any of the other variables, observed or unobserved.

Anyway, the section you're pointing to agrees with me. It just happens to be overlooked when they summarise...

Re: A Philosopher Reviews Judea Pearl's “The Book of Why”

#39
post #34

This presents the RCT criterion uncritically, albeit citing a case where it would be hard to apply. But RCT fails -- gives a nonsense result -- when the hypothesis under test is incoherent. This wouldn't matter, except that RCT is routinely used in such circumstances, and the results treated as gospel by people in positions of authority. Consider: Outcome X may have six causes A-F. RCT tests B, and finds that varying…

A nice point. But this is not a criticism of the RCT so much as a criticism of how its results are used or interpreted.

It is a criticism of the notion of RCT as the unimpeachable "gold standard" of evidence. The limits of a tool are the most important thing to learn about it, and, for RCT, few can be bothered.
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