 Conversational principles can play the same indirect role in implicature recognition that known tendencies or goals play in inductive inference generally. Since speakers commonly observe the Cooperative Principle, and hearers know this in a vague and tacit sort of way, hearers tend to assume that particular speakers are cooperating, in the absence of evidence to the contrary. If the hypothesis that Barb means she is not going to Paul’s party in  example (1)  fits better with the assumption that she is being cooperative than the hypothesis that she is not answering the question, Alan may by abduction infer she is implicating that. Further support for the hypothesis may be provided by the recollection that other speakers have implicated similar things in similar circumstances before. The fact that relevance implicature is a common practice thus provides analogical evidence  (§4).  Recognition of an unconventional form of implicature is more difficult, but no harder than recognizing when a speaker is using a sentence with an unconventional meaning. As Sterelny (1982: 192–3) observed, knowledge of the particular speaker is ultimately more important than knowledge of non-universal generalizations.