translating English ‘or’ into ‘v’ Some uses of ‘or’ suggest an exclusive meaning: (1) My wife is in London or in Oxford (2) Isabel is my daughter or Lily is my daughter But that means ‘or’ is ambiguous, for not all uses are exclusive. How would we tell them apart. Furthermore, put (2) as antecedent of a conditional and it’s not exclusive, yet it’s the same sentence. The ‘strong’ sense of ‘or’ (Grice): ‘A or B’ is true just when (1) ‘A  B’ is true, and (2) there is a nontruthfunctional reason for believing ‘A  B’, that is a reason which is not straightforwardly a reason for believing that ‘A’ is true and which is not straightforwardly a reason for believing that ‘B’ is true. So two conditions for strong ‘v’ being true. If one fails, the disjunction is false. But that’s wrong, see e.g. in lecture 6 slides. Nevertheless, (1) and (2) seem inappropriate if I know the truth of the disjuncts. What’s the explanation?

Recall: PE – proposition expressed by a sentence (its meaning according to the ‘program’ PM – proposition utterer means to convey by uttering a sentence derived by applying Grice’s notion of conversational implicature. If we can locate issues re translation of ‘or’ into FOL around PM, then ‘or’ needn’t be thought ambiguous. Its meaning is given by the FOL translation; the rest is accounted for by PM ideas. Why is it inappropriate to say (2) when I know both disjuncts are true? Perhaps because to utter (2) in such a context is to breach the maxim of Quality – I give less information than I have, similarly with (1).

Similar issues with ‘and’ from earlier lecture. Two possible extra meanings for ‘and’ involving temporal order and causation. Temporal order e.g. – perhaps ‘and’ means what FOL says and the idea of temporal order is a matter of PM, for the maxim of manner requires us to make our conversational contributions orderly – in the order in which things happened. My manner is odd if I asked what I did today I say, ‘I bought a new jacket’ and then add, ‘I caught a bus to town to go shopping’. This isn’t strictly a conversational implicature, but it does seem something about PM, not PE. Causal order – perhaps this is a conversational implicature; Phoebe takes the listener to understand that she’s meeting the maxim of relation (relevance) and manner (perspicuity) to work out that you can tell that it’s been cooked by eating it. So meaning of ‘and’ (PE) is given by FOL; the rest is PM.