vdoc.pub_an-introduction-to-cognitive-linguistics

PROTOTYPES AND CATEGORIES 19
that at some unspecified point or area beyond their periphery the categories
somehow fade into nowhere. This is not the idea we have when we talk
about categories in a naive way. Normally, we tend to imagine them as boxes,
drawers or some sort of fenced compound – certainly as something which
has boundaries. With regard to the category BIRD, the allocation of boundaries
seems to be easy enough, even though a little knowledge of zoology
might be required.
Yet our confidence will be undermined when we follow the philosopher
Max Black and consider the imaginary ‘chair museum’ he invented. According
to Black it consists of
a series of ‘chairs’ differing in quality by least noticeable amounts. At one
end of a long line, containing perhaps thousands of exhibits, might be a
Chippendale chair: at the other, a small nondescript lump of wood. Any
‘normal’ observer inspecting the series finds extreme difficulty in ‘drawing the
line’ between chair and non-chair. (Black 1949: 32)
What Black’s interpretation of his chair museum suggests is that the collection
of chairs could and should be regarded as a continuum with a kind
of transition zone between chairs and non-chairs but no clear-cut boundaries.
This view seems to be in conflict with what we observed at the beginning
of the chapter: that concrete objects like houses, books and also chairs
are clearly delimited and easy to identify, and that vague boundaries and
transition zones are restricted to items like knees, fog and valleys and to
scales like length, temperature and colour.
Here one must be careful not to confuse two different types of boundaries
and transition zones. One type of transition zone arises from the observation
that some concrete entities do not have clear-cut boundaries in reality –
this is the case with knee and other body parts; it applies to fog, snow and
similar weather phenomena and to landscape forms like valley or mountain.
In Black’s chair museum, however, the visitor is confronted with a different
type of transition zone, since each exhibit in the museum is an entity
with absolutely clear boundaries. In the chair museum, it is not entities that
merge into each other, but categories of entities, and these categories are the
product of cognitive classification. Consequently, it is not the boundaries of
entities that are vague, but the boundaries of these cognitive categories (here:
chairs and non-chairs). To distinguish the two types of vagueness we will
restrict the terms ‘vague entity’ and ‘vagueness’ to the first type (knee, fog,
valley) and use ‘fuzzy category boundaries’ or fuzziness for the second, i.e.
for the category boundaries of CHAIR etc.