Generics, Frequency Adverbs, and Probability

Sentence (3.a) may be true even if there has never been any mail from Antarctica;
for example, if handling such mail is part of Mary’s employment contract,
(3.a) could be uttered truthfully. We can imagine coming to the office
and asking John whether any mail has arrived from Antarctica. John may indicate
that he has no knowledge of this, and refer us to Mary by saying (3.a).
John’s sentence may be considered true even if no Antarctic mail has ever
arrived. Similarly, (3.b) may be true even if no emergencies ever occurred,
say in a state of affairs where an obligation to help other members is included
in the club’s constitution.
Note that we are only concerned here with the descriptive readings of
generics, and not with the prescriptive readings.
According to the latter
type of reading, (3.a) is true just in case handling Antarctic mail is Mary’s
job, and (3.b) expresses the existence of a rule obliging club members to help
each other in emergencies. 3 Suppose mail from Antarctica does come in, but
Mary does not do her job properly, so the mail gets piled in the office and
nobody takes care of it; suppose emergencies do eventually occur, but it turns
out that club members fail to help each other. In these cases, the sentences
in (3) would remain true under their prescriptive reading, but would be false
under the descriptive ones.
3 There are languages, such as French (Carlier 1989), which distinguish overtly between
the two readings.
4