Abstract
I argue that an affirmative answer to the question whether entailments could figure as contents of CI is warranted. In particular, the two features of CI that could rule out entailments from the class of contents that could be conversationally implicated are cancellability and non-conventionality. Entailments are non-cancellable, but this is a reason to conclude that they cannot be CIs only if cancellability is a universal property of CIs; alternatively, one might accept CIs that are entailed by what is said and, on this basis, reject the claim that all CIs are cancellable. I see no compelling reason to go one way or another. So, this criterion does not lead to a principled answer to our question. Turning to non-conventionality, this is a defining feature of CIs, according to Grice. I explore the reasons given in the literature for taking non-conventionality to be a defining feature of CI, and argued that none of them are compelling: lexicalization of dead metaphors does not lead to overgeneration of CIs, and calculability is sufficient to distinguish conventional from conversational implicatures. I propose a definition of CI in terms of calculability alone, which does not rule out entailments. So, the answer to our initial question is, eventually, a tentative ‘yes’.
A notable consequence of this definition is that the argument against the cancellability test based on cases of CIs the content of which is entailed by what is said seems a good one after all. This means that CIs are not necessarily cancellable. However, that does not mean that the test is a bad one, inasmuch as non-entailed CIs are still expected to be cancellable.