In an 1992 interview, as a digression while responding to a question on the Mont Pelerin Society, M.F. said:
"As an amusing footnote, one of the major benefits that I personally derived from the first meeting of the Mont Pelerin Society in 1947 was meeting Karl Popper and having an opportunity for some long discussions with him, not on economic policy at all, but on methodology in the social sciences and in the physical sciences. That conversation played a not negligible role in a later essay of mine, "The Methodology of Positive Economics," which has probably led to more pages of subsequent print by others than anything else I've written. It just shows how nature and science works in wondrous ways."
Read the interview here.