 Before discussing briefly this set of alternative quantitative measures of relevance confirmation, we will address one further related issue. It is a long-standing idea, going back to Carnap at least, that confirmation theory should yield an inductive logic that is analogous to classical deductive logic in some suitable sense, thus providing a theory of partial entailment, and partial refutation. Now, the deductive-logical notions of entailment and refutation (contradiction) exhibit the following well-known properties: