A Liberal Conception of Multiple Realizability

While the concept of multiple realizability is widely used, it is sedom rigorously characterized. This paper defends a liberal conception of multiple realizability as sameness of type through any differences in the (lower-level) conditions that give rise to instances of that type. This kind of “sameness through difference” is contrasted with another type of asymmetric dependency relation between properties, multiple specification. This liberal conception is then defended from objections, and it is augmented by a concept of relativized multiple realizability. The last section presents a survey of the ontological, explanatory, and methodological consequences of this analysis of multiple realizability.