Stalnaker: "Presuppositions" (1973)

According to Robert Stalnaker, a person presupposes something

... just in case he is disposed to act, in his linguistic behavior, as if he takes the truth of P for granted, and as if he assumes that his audience recognizes that he is doing so. (p. 448; emphasis in original)

So for instance, Robert Stalnaker presupposes that all speakers are male. His linguistic behavior — here, writing this paper — reveals as much.

This pattern of thought is not just a matter of a pronoun here and there, as we can see if we look at the complete list of examples in the paper. I quote:

1. In some cases, the central purpose of making a statement may be to communicate a presupposition which is required by that statement. For example, someone asks of my daughter, 'how old is he?' I answer, 'she is ten months old'. Or, a says, of the new secretary, 'Jennifer is certainly an attractive woman', b replies, 'Yes, her husband thinks so too'. (p. 449)
2. For example, you ask, 'Who do you think will win the next presidential election?' I answer, 'George McGovern'. Now as a matter of fact in this conversation, we both presuppose from the beginning that Richard Nixon will be one of the candidates [...] Although neither of us does in fact act in any way that indicates that we take it for granted that Nixon will be a candidate, we are each disposed to so act, should the occasion arise. (p. 449)
3. So, for example, I might say, 'Harry doesn't even realize that Nixon is going to run again'. Or, if I wanted to argue to a conclusion that required the premiss that Nixon was a candidate, I would not feel obliged to make that premiss explicit. So for example, I might argue, 'McGovern is going to win, so Nixon will lose'. (p. 449)
4. If I say 'Even George Lakoff might be the Democratic nominee for President this year', I assert exactly what I would assert if I dropped the 'even'. (p. 453)
5. I should emphasize that I do not want to rest any part of my argument on intuitive judgments that statements like 'Even Gödel could prove that theorem', 'If Nixon were President we'd be in a hell of a mess', and 'All of Lyndon Johnson's sons are bastards' in fact have truth values. (pp. 453-54)
6. This principle helps explain the oddity of sentences like "John's aardvark is sleeping, and John has an aardvark'. (p. 454)
7. If I say 'he is a linguist', there must be a particular male (the referent of 'he') who is presupposed to exist, but there is no single male whose existence is required by every use of that sentence. (p. 454)
8. Thus 'John has children and all of his children are asleep' does not require the presupposition that John has children, even though the second conjunct does require this presupposition. (p. 455)

So, it would appear that men are fathers, scientists, and politicians, while women are daughters and secretaries. Only in "odd" sentences are the men placed in less paradigmatic scenes such as owning an aarvaark.