Generics, Frequency Adverbs, and Probability

e.g. usually would be true. This paper argues that all these seemingly
unrelated puzzles have a single underlying cause: generics and frequency
statements express probability judgments, and these, in turn,
are interpreted as statements of hypothetical relative frequency.
1 Eight Puzzles
Generics and frequency statements 1 occur frequently in natural language.
Much of our knowledge about the world is expressed using such sentences—a
glance at an encyclopedia will easily provide myriads of examples. Yet it is
far from clear what such sentences mean, i.e. what a given sentence entails,
what it presupposes, and what it is that makes it true or false.
Perhaps the most puzzling fact about these sentences is that they are,
in a sense, both very strong and very weak. On the one hand, generics and
frequency statements are stronger than simple quantified statements, in being
lawlike; on the other hand, they are weak—they are contingent on properties
of the actual world, and (except, perhaps, for always) are even weaker than
universal statements, since they allow for exceptions.
With a view towards providing a solution to this general conundrum, I will
consider eight specific puzzles in this paper. I will argue that these puzzles
1 Following de Swart (1991) and others, I distinguish between frequency adverbs, such
as usually and always, and other adverbs of quantification, such as twice. I have nothing
to say about the latter type in this paper. I refer to a sentence containing a frequency
adverb as a frequency statement.
2