Hi all, Our next meeting will be *Wednesday March 4*, where Professor James Robins will present research on* “**Causal Mediation Analysis and The Philosophy of Causation**”.* *Abstract:* I introduce an interventionist view of mediation analysis that, unlike standard non-interventionist mediation analysis of Pearl and Vanderweele, (i) does not assume that the mediator has well defined causal effects and/or counterfactuals , (ii) preserves the dictum “ no causation without manipulation” (iii) renders questions of mediation scientific, because eventually testable, (iv) replaces the current complex definitions of path specific effects as nested counterfactuals with easily understood definitions in terms of concrete experimental interventions, (v) facilitates communication with subject matter experts (vi) makes concrete the concept of a “recanting witness” and makes testable the hypothesis that a particular variable is a ‘recanting witness’, (vii) when identified from data, the identifying formulae under an interventionist view and the non-interventionist view are identical; however the effect being identified differs. This talk is based on a joint paper with Ilya Shpitser and Thomas Richardson that generalizes an earlier paper by myself and Thomas Richardson. *Where:* CGIS Knafel Building, Room K354 (see this link <https://map.harvard.edu/?bld=04471&level=9> for directions). *When: *Wednesday, March 4 at 12noon - 1:30pm. All are welcome and lunch will be provided. Best, Georgie