 Kitcher does not propose a completely general theory of how the various considerations he describes—number of conclusions, number of patterns and stringency of patterns—are to be traded-off against one another, but does suggest that it often will be clear enough what these considerations imply about the evaluation of particular candidate explanations. His basic strategy is to attempt to show that the derivations we regard as good or acceptable explanations are instances of patterns that, taken together, score better according to the criteria just described than the patterns instantiated by what we regard as defective explanations. Following Kitcher, let us define the explanatory store \(E(K)\) as the set of argument patterns that maximally unifies K, the set of beliefs accepted at a particular time in science. Showing that a particular derivation is a good or acceptable explanation is then a matter of showing that it belongs to the explanatory store.