Judea Pearl writes:
My previous posting in this forum raised questions regarding Jim Heckman's analysis of causal effects, as described in his article, "The Scientific Model of Causality" (Sociological Methodology, Vol. 35 (1) page 40.)
To help answer these questions, Professor Heckman was kind enough to send me a more recent paper entitled: "Econometric Evaluation of Social Programs," by Heckman and Vytlacil (Draft of Dec. 12, 2006. Prepared for The Handbook of Econometrics, Vol. VI, ed by J. Heckman and E. Leamer, North Holland, 2006.)
This paper indeed clarifies some of my questions, yet raises others. I will share with readers my current thoughts on Heckman's approach to causality and on where causality is heading in econometrics.
(Post edited 5/4: revisions in red, thanks to feedback from David Pattison)
(Post edited 5/17: correction and new comments by LeRoy and Pearl)