Re: Categorisation and Prototypes

From: Murfitt G.R. (
Date: Wed May 29 1996 - 13:13:40 BST

Assignment 4 - What is the classical view of caterogisation ?

Categorisation in general is sorting things. Things fall into
catagories of some sort, and we have to decide how to sort them. For
example, an oak or a fir are in the catagory "tree", but a daffodil
isn't in this catagory.

The classical view of catagorisation is where the classification is
decided by specific features. For example, cats can be classified as
animals having both (a) fur and (b) a tail, and elephants, whilst it
has a tail, does not have fur therefore it is not catagorised as a cat.
Only creatures with both (a) and (b) are cats. This is clearly a very
simplistic example.
Catagories can be much more detailed and complicated than this, with
many, many conditions. Eventually each catagory will only be filled by
one individual item, but this is the issue of vanishing intersections,
which we do not need to go into here. Basically, members of a catagory
have certain necessary and sufficient condidtions for being a member of
that catagory. One circumstance might be that each of two conditions is
neccesary but neither is sufficient on its own, as shown in my earlier

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