APA Dictionary of Psychology

the second of the five canons of empirical science laid down by John Stuart Mill. It is meant to establish sufficient conditions for a phenomenon. For example, if under one condition, C1, an effect, E1, does not occur, and as C1 is changed to C2 the effect E1 does occur, it may be concluded that C2 is a sufficient cause of E1, and the alternative hypothesis, that C1 causes E1, can be eliminated. Thus, the effect is attributed to the “difference” between conditions C1 and C2. Also called difference canon.