Causal and Functional Explanations

Abstract

Functional explanation, for long the mainstay of psychology's autonomy, has recently come under attack. It is sometimes argued that higher-level generalizations are causally impotent, and do not really explain anything. Presumably only the reduction of higher-level patterns to underlying causal physical properties, and the specifying of lower-level, local causal mechanisms, provides genuine explanations. Two lines of argument are critically discussed: causal exclusion and multiple realization. These bear upon the credibility of functional explanation, and upon the presumed explanatory superiority of causal mechanisms over functional higher-level generalizations. It is argued that the causal exclusion argument conflates metaphysics with explanation, and that, rather than pointing towards reductionism, multiple realization indicates the indispensability of higher (functional) generalizations, alongside lower (causal) explanations; the choice for higher or lower level depends on context and explanatory interest. The notion of screening-off suggests a criterion for the legitimacy of higher-level characterizations. A brief example from the history of genetics is discussed to illustrate these ideas. This leads to a plea for pluralism in explanation.