Statistical relevance and explanatory classification

Numerous philosophers, among them Carl G. Hempel and Wesley C. Salmon, have attempted to explicate the notion of explanatory relevance in terms of the statistical relevance of various properties of an individual to the explanandum property itself (or what is here called narrow statistical relevance). This approach seems plausible if one assumes that to explain an occurrence is to show that it was to be expected or to exhibit its degree of expectability and the factors which influence its expectability. But considerations of narrow statistical relevance do not provide an adequate basis for explanatory classification, and the aforementioned views of explanation are accordingly mistaken. Explanatory classification must provide at least a partial account of the nature of a thing, and such an account will generally go beyond what is required as a basis for correct expectation.