Truth-conditional content and conversational implicature

According to some pragmatists, certain conversational implicatures of an uttered sentence may be composed into the truth-conditional content of more complex constructions (e.g. conditionals or comparatives) in which that sentence is embedded. I present two arguments against this view, the one based on the intuitive (in)validity of arguments couched in natural language, the other on the (in)cohence of conversational exchanges; the view in question makes some wrong predictions in both cases. My positive position is that processes of pragmatic enrichment of linguistically encoded meaning (as distinct from conversational implicatures) affect the truth-conditional content of utterances of not only the complex constructions but also of the simpler embedded sentences. 1 Background and overview 1.1 Grice on implicature Grice made a distinction between what is said by a speaker of a verbal utterance and what is implicated. What is implicated might be either conventional (that is, largely generated by the standing meaning of certain linguistic expressions, such as ‘but’ and ‘moreover’) or conversational (that is, dependent on the assumption that the speaker is following certain rational principles of conversational exchange). What appears to have bound these rather disparate aspects of utterance meaning together, and so motivated the common label of implicature, was that they did not contribute to the truth-conditional content of the utterance, that is, the proposition it expressed, or what the speaker of the utterance said. This truth-conditional/non-truth-conditional distinction was essential to Grice in his concern to defeat the ‘illegitimate use’ arguments of a certain group of ordinary language philosophers (Grice 1967, lecture 1). I won’t review those arguments here, but the utility of the distinction and the line of argument it enabled can be demonstrated with the following example. It is odd to produce an utterance of the sentence ‘This looks red to me’, referring with ‘this’ to a patently red pillar-box