 The best known of the works published during Grice’s lifetime was his joint paper with Peter Strawson, “In Defense Of A Dogma”, a widely reprinted defense of the analytic/synthetic distinction against Quine’s attack in “Two Dogmas Of Empiricism”. The best known of his ideas, that of a conversational implicature, first appeared in a 1961 paper “The Causal Theory Of Perception”, but was a focus of the James Lectures. In contrast to the slogan, “meaning is use”, often associated (though perhaps inaccurately) with Wittgenstein, Grice distinguished those elements of language use which were due to meaning from those which are due to other aspects. To illustrate, the sentence “He has not been convicted of a crime yet” means that the person being referred to has not yet been convicted of a crime. But in many contexts, the speaker would be taken to imply that the person had committed at least one crime and was likely to be convicted in the future. In “The Causal Theory of Perception,” Grice deploys the distinction against J. L. Austin’s claim in Sense and Sensibilia that a sentence like ‘It looks to me as if I see something red’ is only correctly used when someone (possibly the speaker) has reason to doubt or deny that the speaker actually sees something red. Austin’s target is sense-datum theorists who attempt to introduce sense-data by appeal to such sentences. Grice argues convincingly that, while using the sentence may typically imply the doubt-or-denial condition, that implication is not part of the meaning of the sentence since the speaker can cancel the implication by adding ‘I do not mean to imply that there is any reason to doubt or deny that I see something red.’ What the speaker means on such a occasion can be true even if the speaker is using the sentence in an usual way, and there is no reason to doubt or deny the speaker sees something red. 