Scientific arguments often attribute the credit or blame for particular experimental or observational results to fragments of theories rather than to the whole of them. The thesis of Theory and Evidence (Glymour 1980) is that there are structural criteria that account for at least part of the distribution of credit and blame; the book also attempts a tentative formal characterization of one structural criterion. David Christensen (1983) has produced a series of counterexamples which show that the formal characterization is untenable. The question remains whether the failure is due to an oversight in the formal theory or to the falsity of the very idea that there are structural criteria for evidential relevance. Since the counterexamples are uniformly eliminated by a single formal principle, I incline to the first answer.