The Many Presuppositions
The label presupposition covers a variety of ideas and the authors may mean different things when they use it.
Pre-requisites One common feature behind the several different meanings of presupposition is the idea that there are conditions. i.e., pre-requisites to be met or satisfied. One school of thought considers that those conditions have to do with truth-values. Another school of thought says that such conditions are those that allow a statement to function properly, i.e., to achieve its goals or serve its purposes.
Truth conditions One intuitive way to characterise the notion of presupposition in an alethic manner is by separating it from the contents of an utterance, i.e., to distinguish the ‘positus’ (what is proposed or put forward for consideration) from what is presupposed by a sentence.
According to a tradition that goes back to Peter of Spain, the existence of the subject (e.f.; Socrates of sentences like (1):
(1) Socrates wrote no book.
is something that is not explicitly stated by the sentence, so it is not part of its contents, but at the same time is one condition for the proposition expressed by (1) to be true. So the existence of Socrates is presupposed by (1).
There are cases that are more complex. Consider the sentences below:
(2) The Pope is a very good Protestant.
(3) The Pope is not a very good Protestant.
Given that (2) is false and (3) is its negation, then (3) should be true. Yet, intuitively the users of any natural language consider both sentences false. Why? One good reason for such intuitions is that both sentences somehow presuppose that the Pope is Protestant, which is false.
There are many thinkable ways to treat the duo proposition and presupposition. One obvious way to do it is by translating a natural language into a conjunct of the type (∃α)(p&q). So, a sentence like:
(4) The man who discovered the Americas was an Iberian.
can be rephrased in this manner:
(4’) There is an x such as x the Americas and X was an Iberian.
Felicity The notion of situational (in-) appropriateness consists of pre-requisites that are called felicity conditions. Felicity conditions determine under what circumstances it is appropriate to ask questions, give commands, etc.
To be continued…
Posted by Tony Marmo at 03:03 BST
Updated: Sunday, 24 July 2005 12:53 BST