“Jean Perrin and Molecular Reality” is reprinted by permission from Perspectives on Science 2 (1994), 396-427 (selected for Philoso­pher's Annual 1994).

This chapter covers some of the same ground as chapter 11.1 include it because it offers a more extensive account of Perrin's reasoning to molecules, as well as a criticism of alternative interpretations of this reasoning proposed by Wesley Salmon, Clark Glymour, and hypothetico-deductivists. Also, it relates Perrin's em­pirical argument to material on evidence in chapter 1.

I.