Generics, Frequency Adverbs, and Probability

⎧
All
⎫
(16)
⎪⎨
No
Some
⎪⎬
birds fly.
⎪⎩
Most
⎪⎭
This is largely true even when the quantifier is vague:
⎧
⎫
Many
⎪⎨
⎪⎬
(17) Several birds fly.
⎪⎩
Hardly any
⎪⎭
Generic sentences such as (18) are also often presented in the literature
as being unproblematically true or false, but it is rarely noted that, in fact,
truth judgments of such sentences are often uncertain, and vary considerably
across individuals.
(18) Birds fly
When, in an informal study, I asked informants to judge the truth of (18),
some agreed that it was true, but many were uncertain, and said things
like, “Well, it’s sort of true, but then there is the penguin.” In contrast,
frequency statements behave like overtly quantified sentences in this regard,
and there is almost unanimous agreement about their truth values; virtually
all informants agreed that (19) was true.
(19) Birds usually fly.
The seventh puzzle, then, is why truth judgments of generics and frequency
statements differ in this manner.
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