**
Similarity **: Likeness.
Judgments that two things are **
similar** are very important in human
reasoning. There are many kinds of similarities, and three important
ones are the following:
- Similarity of A and B because A and
B have one or more properties in
common
- Similarity of A and B because A and
B have (approximately) the same number
of elements
- Similarity of A and B because one is
supposed to be a sample and the other its
population.
The first kind of similarity - having
one or more properties in common - is
the most general, and one to which other kinds of similarity reduce, but
it tends to be not helpful, because it is evident that all pairs of
things, however many different properties they have, also will share
some properties. The second kind is treated by
mathematics. See also: Isomorphism,
Morphism, Frege's Theorem. In general, the most interesting analyses
that have to do with the notion of similarity (and related ones) are
mathematical.
The third kind is treated by statistics,
but also done automatically to some extent by one's
brain, that's quite good at picking up
patterns and (ir)regularities in a statistical sort of way. |