amazon.com/Book-Why-Scien…
To me, Judea is an intellectual hero. My life changed after hearing him at Harvard over 20 years ago. Like many of us in #causalinference, I owe so much to him.
And yet I disagree with him on a key issue.
![](https://pbs.twimg.com/media/DdWbothW0AEOWIY.jpg)
To him, the meaning of “the causal effect of A on death” is self-evident. He says we can quantify, say, the causal effect of race or the causal effect of obesity.
I don't think we can.
For the causal effect of A to be well defined, we need a common understanding of the interventions that we would use to change A. Otherwise, the effect is undefined.
ncbi.nlm.nih.gov/pmc/articles/P…
![](https://pbs.twimg.com/media/DdWcniKWsAE9DBg.jpg)
My view, not Pearl's.
academic.oup.com/aje/article/18…
![](https://pbs.twimg.com/media/DdWc9sVWkAAx9cJ.jpg)
Also, get Pearl's book.