Full Idea
Objection by counterexample is the weakest sort of attack a theory can undergo. Even when the objection succeeds, it shows only that a theory fails to achieve complete accuracy. It does not distinguish among the various rival theories.
Gist of Idea
Objection by counterexample is weak, because it only reveals inaccuracies in one theory
Source
Linda Trinkaus Zagzebski (Virtues of the Mind [1996], III 2.1)
Book Reference
Zagzebski,Linda: 'Virtues of the Mind' [CUP 1996], p.266
A Reaction
Typically counterexamples are used to refute universal generalisations (i.e. by 'falsification'), but canny theorists avoid those, or slip in a qualifying clause. Counterexamples are good for exploring a theory's coverage.