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of a complex concept is determined by its similarity to the exemplars of its
constituents. However, this condition is not satisfied in the general case. So,
for example, a goldfish is a poorish example of a fish, and a poorish
example of a pet, but it s a prototypical example of a pet fish. So similarity
to the prototypic pet and the prototypic fish doesn t predict similarity to
the prototypical pet fish. It follows that if meanings were prototypes, then
you could know what pet means and know what fish means and still
not know what pet fish means. Which is just to say that if meanings were
prototypes, then the meaning of pet fish wouldn t be compositional.
Various solutions for this problem are on offer in the literature, but it
seems to me that none is even close to satisfactory. Let s have a quick look
at one or two.
Smith and Osherson (1984) take prototypes to be matrices of weighted
features (rather than exemplars). So, for example, the prototype for
APPLE might specify a typical shape, colour, taste, size, ripeness, . . . etc.
Let s suppose, in particular, that the prototypical apple is red, and consider
the problem of constructing a prototype for PURPLE APPLE. The basic
idea is to form a derived feature matrix that s just like the one for APPLE,
except that the feature purple replaces the feature red and the weight of
the new colour feature is appropriately increased. PET FISH would
presumably work the same way.
It s pretty clear, however, that this treatment is flawed. To see this, ask
yourself how much the feature purple weighs in the feature matrix for
PURPLE APPLE. Clearly, it must weigh more than the feature red does
in the matrix for APPLE since, though there can be apples that aren t red,
there can t be purple apples that aren t purple; any more than there can be
red apples that aren t red, or purple apples that aren t apples. In effect,
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Prototypes and Compositionality 103
purple has to weigh infinitely much in the feature matrix for PURPLE
APPLE because purple apples are purple, unlike typical apples are red, is a
logical truth.
So the Smith/Osherson proposal for composing prototypes faces a
dilemma: either treat the logical truths as (merely) extreme cases of
statistically reliable truths, or admit that the weights assigned to the
features in derived matrices aren t compositional even if the matrices
themselves are. Neither horn of this dilemma seems happy. Moreover, it s
pretty clear what s gone wrong: what really sets the weight of the purple in
PURPLE APPLE isn t the concept s prototype; it s the concept s logical
form. But prototypes don t have logical forms.
Another way to put the pet fish problem is that the features associated
with the As in AN constructions are not, in the general case, independent
of the features associated with the Ns. So, suppose that the prototype for
NURSE includes the feature female. Pace Smith and Osherson s kind of
proposal, you can t derive the prototype for MALE NURSE just by
replacing female with male; all sorts of other things have to change too.
This is true even though the concept MALE NURSE is intersective ; i.e.
even though the set of male nurses is the overlap of the set of males with
the set of nurses (just as the set of pet fish is the overlap of the set of pets
with the set of fish). I want to stress this point because prototype theorists,
in their desperation, are sometimes driven to suggest that MALE NURSE,
PET FISH, and the like aren t compositional after all, but it s all right that
they aren t, since they are idioms. But surely, surely, not. What could be
stronger evidence against PET FISH being an idiom or for its being
compositional than that it entails PET and FISH and that {PET, FISH}
entails it?
It s perhaps worth mentioning the most recent attempt to salvage the
compositionality of prototypes from pet fish, male nurses, striped apples,
and the like (Kamp and Partee 1995). The idea goes like this: maybe good
examples of striped apples aren t good examples of striped things tout
court (compare zebras). But, plausibly, a prototypic example of a striped
apple would ipso facto be as good an example of something striped as an
apple can be. That is a way of saying that the relevant comparison class for
judging the typicality of a sample of apple stripes is not the stripes on
things at large but rather the stripes on other apples; it s these that typical
apple stripes are typical of. In effect, then, what you need to do to predict
whether a certain example of apple stripes is a good example of apple
stripes, is to recalibrate STRIPES to apples.
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