H. P. Grice, answered from the texts and cited to the page.
Senses are not to be multiplied beyond necessity.1 Where the apparent ambiguity of a natural-language connective — "or" between exclusive and inclusive readings, "if" between material and conditional readings, "and" between mere conjunction and temporal-causal sequence, "not" between contradictory and other-than readings — can be handled by an account that posits a single semantic meaning plus a generalised conversational implicature triggered in standard contexts, the pragmatic account is to be preferred over the polysemy account.
The distinction between what is said (truth-conditional) and what is implicated (calculable from the said plus the Cooperative Principle) is a real distinction even where the line is hard to draw in particular cases. Conventional implicatures — the contrast carried by "but," the consequence carried by "therefore," the additivity carried by "moreover" — are detachable from the truth conditions and are part of the conventional meaning of the words, distinct from both what is said and what is conversationally implicated.2345
I offer three further reflections about the proliferation of senses. 1. I would like to propose for acceptance a principle which I might call Modified Occam's Razor, Senses are not to be multiplied beyond necessity. Like many regulative principles, it would be a near platitude, and all would depend on what was counted as "necessity." Still, like other regulative principles, it may guide.Studies in the Way of Words, p. 47
Further Notes on Logic and Conversation I would like to begin by reformulating, in outline, the position which I took in Essay 2. I was operating, provisionally, with the idea that, for a large class of utterances, the total signification of an utterance may be regarded as divisible in two different ways.Studies in the Way of Words, p. 41
For to say that A or B (interpreted weakly) would be to make a weaker and so less informative statement than to say that A or to say that B, and (on the assumption, which I shall not here try to justify, that it would be of interest to an audience to know that one of the disjuncts is true) would therefore be to make a less informative statement than would be appropriate in the circumstances.Studies in the Way of Words, pp. 46–47
So the "proof" given in the Thesis is invalid. III. It may be possible to reach a solution of this puzzle by invoking my bracketing device. If it should be true that "if A, B" means, or at least has the effect of, "[either not-A or]B," then "A:J B" will yield "if A, B," but the negation of "if A, B" will not yield the negation of "A:J B"; in which case the paradox disappears.Studies in the Way of Words, pp. 86–87
But this, in the examples mentioned, does not seem to be possible; in anything but perhaps a very special case to say It is not the case that A or B seems to amount to saying that neither A nor B (that is, cannot be interpreted as based on a denial of the second condition), and to say Suppose that A or B seems to amount to inviting someone to suppose merely that "' 111 ' 46 Logic and Conversation.Studies in the Way of Words, p. 46
The methodological signature of the Logic-and- Conversation programme and the basis for the pragmaticist treatment of natural-language connectives that has dominated philosophy of language and semantics since 1967. The neo-Gricean programme (Horn, Levinson) develops the line. Conventional implicature is more contested: Kent Bach (1999) denies it as a category, arguing that the phenomena attributed to it are either part of what is said or part of conversational implicature; Christopher Potts (2005) defends and formalises the category. The contextualist tradition (François Recanati, Kent Bach, Robyn Carston) argues that what-is-said is contextually enriched beyond conventional meaning, blurring the said/ implicated line at the boundary. The minimalist line (Cappelen and Lepore) defends a tighter said/implicated distinction.