RSS West Midlands Local Group welcomed Professor David Papineau of King’s College London and City University New York to talk about an interesting intersection of statistical and philosophical thinking. The event took place on Thursday 5 December at the University of Warwick. It was well-attended by an audience made up of both philosophers and statisticians.
Professor Papineau began by discussing the history of the study of causation in statistics, highlighting the more recent notoriety of Judea Pearl, especially since the publication of The Book of Why, but also prior work of HA Simon, HM Blalock, Ronald Fisher, Sewall Wright and Tinbergen, Frisch and Haavelmo. His claim was that this work in recovering causal structure from correlational (by which he took a broader meaning of dependence) structure pointed towards a metaphysical moral, that causal structure just is correlation structure.
He sought to explain what he described as the ‘reductive basis’ for which he was arguing, explaining that he considered there to be two levels of causal inference. First the inference of ‘lawlike’ population level correlations from sample data, and second the inference of causal structure from these lawlike correlations. He made clear that it was the second of these with which he was interested.
In this context he claimed that what statistics showed was that the philosophical claim “no causes in, no causes out” was simply incorrect. He used some simple examples of directed acyclic graphs to explain how causation could be inferred from correlation. A murmur was heard from the statisticians in the audience when he went on to claim that 'B can only be spuriously correlated with C if it is itself an effect of one of C’s true causes'.
He then returned to explaining that philosophers predominantly think of causes and effects independent of these considerations of correlation. But he claimed that these considerations make for cause and effect, and that this was a reduction of causation. Returning to Pearl, he noted that Pearl had described the statistical signatures of causation as 'a gift from the gods', but he expressed that with his reductive view of the metaphysics of causation then no such divine recourse was necessary. His challenge to philosophers was as he put it 'to explain why the statisticians’ arrows coincide with the causal arrows?; why are event types probabilistically independent if and only if they are causally independent?' with his own conclusion being that an answer to the question must hinge somehow on the nature of causation.
The engagement of the audience was expressed in the numerous questions that Professor Papineau fielded. These included queries on topics including the role of agents, on the role of randomness and uncertainty, and on the implication that observation alone (as opposed to designed experiments) might be the best means of inferring causation.