 The position that I’ve sketched here is the position that Lewis says that he originally was drawn towards in 1975, and that he endorsed in print in 1994. (The dates are from his own description of the evolution of his views in (1994a).) But in between, in both (1980a) and Postscript C to its reprinting in (1986b), he rejected this position because he thought it conflicted with a non-negotiable conceptual truth about chance. This truth was what he called the “Principal Principle”.