Full Idea
Given the Regularity theory, the explanatory element seems to vanish. For to say that all the observed Fs are Gs because all the Fs are Gs involves explaining the observations in terms of themselves.
Gist of Idea
To explain observations by a regular law is to explain the observations by the observations
Source
David M. Armstrong (What is a Law of Nature? [1983], 06.7)
Book Reference
Armstrong,D.M.: 'What is a Law of Nature?' [CUP 1985], p.102
A Reaction
This point cries out, it is so obvious (once spotted). Tigers are ferocious because all tigers are ferocious (see?).