Watanabe's Theorem of the Ugly Duckling

This entire post is quotes from Kanal (1993)

Theorem of the Ugly Duckling
(by Watanabe)
If the resemblance or similarity between two objects is measured by the maximum number of predicates shared by them, then the similarity between any pair of arbitrary objects is the same. Thus a swan and a duck, and two swans are equally similar. This situation arises because all predicates are treated equally.
...performing logical manipulation on raw data resulting from observation does not provide grouping among observed objects because unless some predicates are considered more important than others, i.e., weighted more heavily, the above theorem holds.

What makes human cognition possible is the evaluative weighing whose origin is aesthetic and emotional in the broadest sense of the terms.

In Pattern Recognition - Human and Mechanical he summarizes earlier papers of his that cover a variety of philosophical views on categorisation, from Greeks and Western philosophers to Brahmanism and Buddhism.

many of the points about categorisation touched on in Wantabe's papers and books are addressed at length in an excellent book by George Lakoff called Women, Fire and Dangerous Things (see)