Roberts on Observable Causal Facts
In a previous post, I argued that Earman and Roberts, in their 2005 PPR articles on Humean Supervenience (HS) about laws of nature, were implicitly relying on the view that nomic facts (such as singular causal facts) are unobservable. There followed an interesting discussion. But the question that none of us could answer was, what do Earman and Roberts think about HS vis a vis the observability of nomic facts?
John Roberts wrote me as follows (reproduced by permission):