 In Chicago, Salmon was quite unhappy with the Thomistic focus of the Philosophy department, where the scientifically oriented philosophy he favored was somewhat disregarded, in spite of the presence there of Rudolf Carnap, with whom at that time he did not have much interchange. Closer interaction between them took place in 1963, while Salmon was visiting the University of Minnesota Center for Philosophy of Science for the Winter and Spring terms, and was given the opportunity to pay a one week visit to Carnap in Los Angeles, together with Herbert Feigl, and Grover Maxwell. That visit was the occasion for daily discussions on the nature of confirmation and inductive logic. Such a stimulating exchange fueled many writings, including the masterpiece The Foundations of Scientific Inference (1967a), whose fiftieth anniversary edition was re-published in 2017 with an introduction by Christopher Hitchcock.