Abstract

Philosophers frequently extract two lessons from Moliere's joke about the doctor who tried to explain why opium puts people to sleep by claiming that it has a dormative virtue. First, the principle I will call the equivalence thesis: attributions of dispositional properties are equivalent to certain associated subjunctive conditionals. The second is what I will call the reducibility thesis: for a dispositional concept to be nonproblematic, its “physical basis” must be found. In what follows, I will briefly describe three theoretical positions that have been defended in different areas of psychology. Each claims that a certain disposition does not exist, even though the associated subjunctive conditional is not called into question. Besides showing that the equivalence thesis is mistaken, these examples also illustrate how that doctrine in fact conflicts with the requirement of reducibility. Not that that demand can withstand criticism either; both the equivalence claim and the reducibility claim are mistaken.