Multiple Realizability and Disjunction for the Special Sciences

One way to secure the autonomy of special sciences like psychology is to block reductive strategies by assuming that higher-order properties in psychology are multiply realizable. Multiple realizability would then secure both metaphysical irreducibility and dependency by exploring the variety of ways in which higher-order phenomena can be realized in different systems. Originally, a promising way to understand this variability was in terms of the possible realization role played by property disjunction. However, the non-projectability of disjunctive predicates into explanatory generalizations undermines the multiple realizability strategy mainly because a condition for these generalizations to have scientific weight is that they be based on the existence of natural kinds. Traditionally, disjunctive properties have no reference to kinds. In this paper I explore the character of disjunctive properties as cases of homeostatic property clusters sufficient to be classified as genuine natural kinds, and the consequences for the question of the autonomy of the special sciences.