3.3 Triggers, accommodation, & presupposition failure

Where in a sentence do presuppositions originate?

Factive presuppositions arise from a variety of expressions. These include propositional attitude verbs like 'know', 'regret', 'realise'. Note that not all such verbs trigger presuppositions, as shown in the contrast between (21) and (22). This distinction is part of the lexical knowledge that a speaker of English has regarding the behaviour of individual verbs: "know" is used to convey that the subject has a belief about something that is a known fact; "believe" is used to convey only that the subject holds in their head a thought, which may or may not be a known truth.

Below is a list of other triggers for factive presuppositions. See if you can identify the presupposed content in each example.

In the case of existential presuppositions, the surface form matters. It's the speaker's choice of form that acts as the trigger. Specifically, the form of noun phrase that is used or the syntactic construction that is chosen. In (23), the proper name "Arnold" yields a presupposition.

Below is a list of other triggers for existential presuppositions. See if you can identify the presupposed content in each example.

Another type of presupposition arises in languages which have different forms to indicate levels of politeness: e.g., German 'du'/'sie', French 'tu'/'vous'. The more polite forms can be said to presuppose a level of formality between the interlocutors.

In discourse, there are occasions when a presupposition 'fails', i.e., the truth of the presupposed proposition is not taken for granted by all participants in the conversation. When that happens, the discourse either derails or the presupposition is accommodated.

A symptom of discourse derailment is that the direction of the conversation is interrupted; someone jumps in and says "Hey, wait a minute!". Another characteristic of presuppositions is that a speaker can only deny or draw attention to them with an interruption like "hey wait a minute". Entailments, on the other hand, can be disagreed with via a more direct "That's false".

The fact that a failed presupposition may be met with a "Hey, wait a minute!" response, makes it a great test. The response is only felicitous for disputing a presupposition, not a main assertion, as shown in example (30).

Presupposition failure need not necessarily lead to discourse derailment. There are contexts in which a presupposition is easily accommodated. If a student says "I have to leave class early to pick up my sister at the airport", it is easy enough to accommodate the existence of the sister (note that the existence of "my pet giraffe who is arriving on a flight from Cameroon" is a lot harder to accommodate). Accommodation proceeds as follows:

• Speaker utters a sentence p with presupposition q
• Listener doesn't know q
• Listener infers from Speaker's uttering p that Speaker takes q for granted
• Listener concludes that q is true
• Listener accepts q into the common ground
• Communication of p succeeds

In some cases, this happens almost automatically. Consider the presupposition triggers in (27) and (28) and their associated presupposed propositions. The propositions pass the tests for presupposition but their failure to have been previously introduced into the conversation does not lead to discourse derailment. In fact, for (28), it would be downright odd for someone to respond "Hey, wait a minute, there was a waiter in the restaurant?!"

There are also cases in which a presupposition trigger is used without a presupposition arising at all. It's possible to utter the sentences in (29-30) without seeming to contradict oneself. In (29), the possessive noun phrase "my sister" normally would trigger a presupposition that the speaker has a sister. However, the example shows that the speaker is using this possessive NP in a different way. This is called a metalinguistic interpretation. Perhaps the speaker is responding to someone else's statement that invoked this non-existent sister.

Content adapted from S. Kaufmann (2008) teaching materials, Northwestern University.