Some concerns with Polger and Shapiro’s view

Abstract

This paper provides some responses to Tom Polger and Larry Shapiro’s The Multiple Realization Book (2016). I first provide a description of the authors’ framework for thinking about multiple realization and the conditions they claim this involves. I explain what I think they get right and what they get wrong with this framework. After this, I then consider a few examples of multiple realization they discuss and the interpretations they offer. While I am sympathetic to several things they say about multiple realization, I also think there are some questions that have yet to be answered.

Keywords:

• Functionalism
• multiple realization
• scientific practice
• taxonomies

Notes

1. Elsewhere they write, “Multiple realization is a claim about the dissimilarity of two taxonomies” (p. 61 n1).

2. Polger and Shapiro are neutral about whether the relata of realization are properties, states, kinds, or other entities (p. 22). I will usually talk about properties or kinds, depending on which is appropriate in the context.

3. Let me make clear that I am thinking of the explanatory notion involved here as an objective explanatory relation in the world and not as an epistemological notion of explanation. The issue is whether the presence of a property serves metaphysically to explain the presence of a function. This isn’t to deny that there may be legitimate epistemological senses of explanation.

4. Polger and Shapiro say that “considerations such as convergence do not predict a univocal answer [to multiple realization], contrary to Block and Fodor’s suggestion” (p. 144). This seems too strong, since Block and Fodor only say that “psychological similarities across species may often reflect convergent environmental selection rather than underlying physiological similarities” (Block & Fodor, 1972, p. 161) and I also presume they are aware of the mammal-cephalopod case.