Abstract. This paper illustrates how philosophy and science may converge and inform one another. I begin with a brief rehearsal of John Morreall’s “formulaic” theory of laughter, that laughter results from a pleasant psychological shift, and of my previously published criticisms and counterproposal that laughter results from titillation (where “titillation” is a semitechnical term). I defend my own position against charges that it is trivial, circular, or vacuous (charges that, if correct, would apply equally to Morreall’s position), showing that these charges are misguided or premature. Then I indicate how my position is reflected in and might be given empirical content by a hypothesis that is already under preliminary experimental investigation in psychology, namely the Darwin-Hecker hypothesis, and also how my position is in harmony with recent work in psychology alleging the discovery of evolutionary antecedents of human laughter in rats.