  Wimsatt's writings on reduction (1976a, 1976b, and 1979) emphasize the fruitfulness of attempting to achieve a reduction, even when a reduction is not achieved. He argues, for instance, that efforts to discover the molecular make-ups of entities identified at higher levels is often fruitful, even when identities between levels cannot be found. In addition, Wimsatt points out that the “costs” of working out reductive explanations of the many particulars already explained at a higher level are relevant to the question of why there is not a full-scale replacement of higher level explanations with lower level ones. Perhaps the fact that molecular genetics has not replaced classical genetics can be explained on the basis of high costs rather than lack of epistemic merit. 