Analysis of Borden's papers, including unpublished (to 1975), to discover logic used to formulate and test hypotheses. Available data and explanatory patterns shown. Work characterized as search for Northwest Coast chronology with three periods: Early. Evidence from stratigraphy, geology, historical linguistics, ethnographies, study of spatial distribution of similar artifacts. Middle. Application of 0-14 dating to test and correct earlier hypotheses. Recent. Sequences of hypotheses to explain complex, puzzling phenomena involving many basic sciences. Papers shown to be series of retroductions, moving from puzzling phenomina to hypotheses from which the phenomena would follow as a matter of course.