In that year, he moved to the United States to take up a professorship at the University of California, Berkeley, where he taught until his death in 1988.

[5] Grice further developed his theory of meaning in the fifth and sixth of his William James lectures on "Logic and Conversation", delivered at Harvard in 1967.

Grice does not define these two senses of the verb 'to mean', and does not offer an explicit theory that separates the ideas they're used to express.

The more common label in contemporary work is "speaker meaning", though Grice didn't use that term.)

The net effect is to define all linguistic notions of meaning in purely mental terms, and to thus shed psychological light on the semantic realm.

[11] Grice's initial definition was controversial, and seemingly gives rise to a variety of counterexamples,[12] and so later adherents of intention-based semantics—including Grice himself,[13] Stephen Schiffer,[14] Jonathan Bennett,[15] Dan Sperber and Deirdre Wilson,[16] and Stephen Neale[17]—have attempted to improve on it in various ways while keeping the basic idea intact.

Grice would give a much more detailed theory of timeless meaning in his sixth Logic and Conversation lecture.

[19] Grice's most influential contribution to philosophy and linguistics is his theory of implicature, which started in his 1961 article, "The Causal Theory of Perception", and "Logic and Conversation", which was delivered at Harvard's 'William James Lectures' in 1967, and published in 1975 as a chapter in volume 3 of Syntax and Semantics: Speech Acts.

One point of controversy surrounding Grice's favoured notion of saying is the connection between it and his concept of utterer's meaning.

[26]Grice never spelled out what he meant by the phrase "closely related" in this passage, and philosophers of language continue to debate over its best interpretation.

This latter way of drawing the distinction is an important part of John Searle's influential theory of speech acts.

The difference between the two lies in the fact that what a speaker conventionally implicates by uttering a sentence is tied in some way to the timeless meaning of part of the sentence, whereas what a speaker conversationally implicates is not directly connected with timeless meaning.

[28]Grice did not elaborate much on the notion of conventional implicature, but many other authors have tried to give more extensive theories of it, including Lauri Karttunen and Stanley Peters,[31] Kent Bach,[32] Stephen Neale,[33] and Christopher Potts.

Cooperative Principle: "Make your contribution such as it is required, at the stage at which it occurs, by the accepted purpose or direction of the talk exchange in which you are engaged."

The conversational maxims can be thought of as precisifications of the cooperative principle that deal specifically with communication.

[37] Perhaps Grice's best-known example of conversational implicature is the case of the reference letter, a "quantity implicature" (i.e., because it involves flouting the first maxim of Quantity): A is writing a testimonial about a pupil who is a candidate for a philosophy job, and his letter reads as follows: "Dear Sir, Mr. X's command of English is excellent, and his attendance at tutorials has been regular.

)[38] Given that a speaker means a given proposition p by a given utterance, Grice suggests several features which p must possess to count as a conversational implicature.

"[40] Non-Conventionality: "...conversational implicata are not part of the meaning of the expressions to the employment of which they attach.

[43] In his book Studies in the Way of Words (1989), he presents what he calls Grice's paradox.

In fact, (ii) and (iii) don't provide enough information to use Bayesian reasoning to reach those conclusions.

Grice's paradox shows that the exact meaning of statements involving conditionals and probabilities is more complicated than may be obvious on casual examination.