Published online by Cambridge University Press: 28 February 2022
Explanations sometimes involve a certain asymmetry. For example, given Ohm's Law and the voltage of a battery, one can calculate the current in an electric circuit if one knows the resistance, or one can calculate the resistance if one knows the current. Both of these calculations are (roughly) deductive-nomological arguments, but only the calculation of the current from the resistance is an explanation. Why should only one of these calculations be an explanation?
One plausible diagnosis of such explanatory asymmetries is that they arise from the asymmetry of causal relations (see, for example, Salmon 1978 or Beauchamp and Rosenberg 1981, p. 313). The direction of explanation is the direction of causation. The resistance of the wire is a causal condition influencing the amount of the current, while the amount of current does not (as a first approximation) influence the resistance.
I am deeply indebted to many more people than can be named here. Particularly to be thanked are Douglas Ehring, without whose help I could never have made progress with the problems of causal asymmetry, and Eugene Pidzarko, David Sanford and Paul Thagard, who offered helpful criticisms of the paper. My research was generously supported by the National Science Foundation (Grant #SES 8007385).