Donald T. Campbell
Donald Thomas Campbell ( * November 20, 1916; † 5 May 1996) was an American psychologist.
Campbell coined the term evolutionary epistemology and developed a selection- based theory of creativity based on the downward causation. To interpret research results to be valid, he pleaded to investigate the same subject with different methods - an approach which he described with the metaphor of triangulation.
Together with Donald W. Fiske, he invented the method of multitrait - multimethod matrix to verify the construct validity. The article, in which they introduce this method is one of the most cited in the social sciences.
Campbell had a strong influence on the metaphysical period of Karl Popper, who emphasized " the almost complete, going down to the smallest detail correspondence between Campbell's views and my own ."