Semantics: a coursebook, second edition

PA RT  T WO
From reference . . .
86
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(1) Yes (2) Yes (3) No (4) Evolution proceeds in such minute stages that 
one has the impression of a continuum. We do not have a clear enough
idea of what is and what is not a chicken (or a chicken’s egg) to be able to
tell with any certainty which one in a long line of very subtly changing
objects is the ‘
first’ chicken(’s egg).
Comment The point is that even people who can reasonably claim to know the meaning
of chicken cannot draw a clear line around the set of all chickens, past, present,
and future, separating them from all the non-chickens. In short, the extension
of chicken is not a clear set. It is a ‘fuzzy set’, and fuzziness is far from the
spirit of the original idea of extensions. This fuzziness is a problem which
besets almost all predicates, not only chicken and egg.
Practice (1) If all the ancestors of some modern cat, going back as far as 
pre-cats, were available for inspection, do you think it would 
be possible to tell clearly which one of them was ‘the 
first cat’?
Yes / No
(2) Is the extension of cat a clearly de
fined set?
Yes / No
(3) Can you imagine 
finding some creature in the woods and,
despite thorough inspection, not being able to decide whether 
it should be called a ‘cat’ or not?
Yes / No
(4) Is the ‘present extension’ of cat (what we have called the 
extension of is a cat) a clearly de
fined set?
Yes / No
(5) Could a potter make some object which was halfway 
between a cup and a mug? If so, what would you call it?
..........................................................................................................................
(6) Could a whimsical carpenter make an object that was halfway between a
table and a chair? If so, what would you call such an object?
..........................................................................................................................
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(1) No (2) No (3) Yes, this situation is imaginable. (4) No (5) Yes; it would 
be hard to know whether to call it a cup or a mug. (6) Yes; it would be
hard to know whether to call it a chair or a table.
Comment In practice, certain kinds of predicates present more di
fficulties than others.
It is unusual, in everyday situations, for there to be much problem in
applying the predicates cat, or chicken. Cats and chickens are natural kinds,
which the world obligingly sorts out into relatively clear groups for us. But in
the case of some other kinds of predicates, it is obvious that everyday
language does not put well-de
fined boundaries around their extensions. A
good example of this is the di
fficulty people often have in deciding what the
boundary is between two similar colours, as shown in the following practice.

U N I T   8

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