Philosophy of science may indeed perform a valuable normative function through historical analyses of characteristic errors, as Bechtel (1982) argues. But considerations of the two types of errors elected for this role, and harder looks at some of the historical examples prosecuted for these errors, disclose few helpful hints beyond the wisdom provided in Chapter I of freshman science texts coupled to a clear view of the future. To avoid churlishly spurning at first glance this offer of assistance, however, let us look in turn at the two candidates with their supporting examples.