Generics, Frequency Adverbs, and Probability

(13) Birds (usually) fly.
Generics and frequency statements, then, express contingent, rather than
necessary statements. It should be emphasized that this fact does not preclude
their being lawlike.
The following sentences are lawlike (and true),
although they do not express necessary properties, under any conceivable
definition of necessity:
(14) a. A cheetah outruns any other animal.
b. Spices are affordable.
c. Gold cubes are smaller than 10 cubic meters (adapted from Koningsveld
1973, 60).
d. Dogs annoy Sam.
Perhaps running fast is a necessary property of cheetahs, but certainly not
the property of running faster than any other animal, since some other animal
might have been faster. Affordability is a contingent property of spices—in
fact, throughout much of history, spices were extremely expensive; yet (14.b)
is true nonetheless. Similarly, we would be hard-pressed to claim that gold
cubes are necessarily smaller than 10 cubic meters, or that annoying Sam
is a necessary property of dogs. The fifth puzzle, then, is how generics and
frequency statements can express contingent facts, and yet be lawlike.
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