 There is significant consensus that “Shaq is tall but agile” and “Shaq is tall and agile” are true in all the same circumstances. But the latter doesn’t communicate a contrast between tallness and agility. The implicated contrast proposition isn’t part of the truth-conditions of B’s utterance. The implicature is widely regarded as conventional because the contrast seems to be part of the standing meaning of but in English; a speaker who finds no difference between what and and but communicate is in some sense not fully competent with but. An implicature of an utterance that needn’t be carried by an utterance of a truth-conditionally equivalent sentence is said to be “detachable” from the utterance (Grice 1975: 39). In  section 2.1  we saw that according to R.M. Hare the evaluative content of thick terms is detachable in this sense. But he doesn’t say whether he thinks that the evaluative contents of thick terms are conventional implicatures. If the evaluations normally conveyed by T-utterances were conventional implicatures (or semantic presuppositions, for that matter), then thick terms would be inherently evaluative in meaning, but not as a matter of truth-conditions. One problem for this view is that conventional implicatures aren’t defeasible in the ways that the evaluations normally conveyed by T-utterances seem to be: “Whether or not Shaq’s agility is unexpected given his tallness, Shaq is tall but agile” sounds very odd.