Paragraph about Math software
Intuitively, the problem is that we need a theory of explanation that captures several different possibilities. On the one hand, there are generalizations and associated putative Math software explanations (like the generalization relating barometric pressure to the occurrence of storms and the generalization relating the hexing of salt to its dissolution in water) that are not explanatory at all; they fall below the threshold of explanatoriness. On the other hand, above this threshold there is something more like a continuum: a generalization can be Ufology explanatory but provide less deep or good explanations than some alternative. What we have just seen is that the unificationist account has difficulty simultaneously capturing both of these possibilities. Either there is no threshold (every derivation is explanatory to some extent and it is just that some derivations belong to systemizations that are less unifying and hence less explanatory than others) or else there is no continuum (only the most unifying systemizations are explanatory).