A small portion of H.P. Grice's 1967 'William James lectures', delivered at Harvard University. G. frames the term 'implicature' to cover meanings that are implied, suggested, meant, etc. but not 'said' in what he calls the favoured sense of that word. 'Conventional implicatures' are said to be derivable from the conventional meaning of words (e.g. 'He is an Englishman; he is, therefore, brave' conventionally implicates that being brave is a consequence of being an Englishman, because of the presence of 'therefore'). A subclass of non-conventional implicatures, viz. 'conversational implicatures' are implicated meanings that can be worked out by the hearer on the basis of a set of 'maxims of conversation'. G. lists maxims of 'quantity', 'quality', 'relation' and 'manner'. There is one supermaxim, the 'cooperative principle', i.e. 'Make your conversational contribution such as is required, at the stage at which it occurs, by the accepted purpose or direction of the talk exchange in which you are engaged'. (E.g. 'There is a garage around the corner' conversationally implicates - if uttered in answer to 'I am out of petrol' - that the garage is open and has petrol to sell, because otherwise the utterance would be uncooperative). G. even tries to explain phenomena such as irony and metaphor in such terms.