In the linguistic field of

pragmatics In linguistics and related fields, pragmatics is the study of how context contributes to meaning. The field of study evaluates how human language is utilized in social interactions, as well as the relationship between the interpreter and the in ...

, an inference is said to be defeasible or cancellable if it can be made to disappear by the addition of another statement, or an appropriate context. For example, sentence would normally implicate iby

scalar implicature In pragmatics, scalar implicature, or quantity implicature, is an implicature that attributes an ''implicit'' meaning beyond the explicit or ''literal'' meaning of an utterance, and which suggests that the utterer had a reason for not using a more ...

: :i: Alice has three children. :ii: Alice has exactly three children. But the implicature can be cancelled by the modification in b :ib: Alice has three children, and possibly more. Whereas conversational

implicatures In pragmatics, a subdiscipline of linguistics, an implicature is something the speaker suggests or implies with an utterance, even though it is not literally expressed. Implicatures can aid in communicating more efficiently than by explicitly sayi ...

and

presuppositions In the branch of linguistics known as pragmatics, a presupposition (or PSP) is an implicit assumption about the world or background belief relating to an utterance whose truth is taken for granted in discourse. Examples of presuppositions inclu ...

may be cancelled, an

entailment Logical consequence (also entailment) is a fundamental concept in logic, which describes the relationship between statements that hold true when one statement logically ''follows from'' one or more statements. A valid logical argument is one ...

may not be. For example, entails the proposition "Alice has at least three children", and this cannot be cancelled with a modification like: :ic: Alice has three children, and possibly less.

Explicit and contextual cancellation

Grice The grice was a breed of swine found in the Highlands and Islands of Scotland and in Ireland. Culley, George(1807), ''Observations on Livestock'', pub Wilkie, Robinson et al, p 176/ref> It became extinct, surviving longest in the Shetland I ...

, the originator of the concept of implicature, draws a distinction between ''explicit'' and ''contextual'' cancellation.Grice, H.P. (1978). "Further Notes on Logic and Conversation," ''Syntax and Semantics'', vol.9 edited by P. Cole, Academic Press. Reprinted as ch.3 of Grice 1989, 41–57. He calls an implicature ''p'' explicitly cancellable if it is possible to cancel it by adding a statement to the effect of "but not ''p''" to the utterance which would otherwise implicate it. For example: :There's beer in the fridge. An implicature is contextually cancellable if it can fail to manifest in a different context. For example, if Bob says "We have two spare bedrooms", this would normally implicate that his house has exactly two spare bedrooms. But this implicature disappears if Bob is speaking with Carole and Diane who are planning a visit to Bob's city and looking for a place to stay.

References

{{reflist Pragmatics Inference