It seems analogies of many kinds are one of the main foundations of
understanding and explaining, and that one basic principle that is involved is
the following heuristic assumption (that is
supported by most experience):
- What is similar in some known respects is
also similar in some further respects.
This has always been an important heuristic
principle of explanation, and there is a
modern mathematical explanation of analogy
in terms of morphisms (isomorphisms or homomorphisms) that has the merits of
both clarifying analogy itself, namely in terms of sameness of form, and of
suggesting why analogies are important in cognition.
1. Analogy and induction: One important class of arguments that
depend to some considerable extent on analogies of some kind are
inductive generalizations of the kind
'unobserved cases of so-and-so will be like observed cases of so-and-so', 'the
future of such-and-such will be like the past of such-and-such', etcetera.
These are not deductively
valid but it may be argued they are better -
more probably true - in proportion to the strength of the analogy (or
analogies) that is (or are) involved. (See:
One problem here is that it is difficult or impossible to give a good
general theory that establishes the strength of analogies.
2. Analogy and thinking: It is clear that analogies of many kinds
are involved in human thinking, since much of
that is based on representing something A,
that often is only partially known and/or partially accessible, as if it were
something B (a model, mock-up, imitation, diagram, verbalization, equation or
tale of A), that is far better known or far better accessible than is A
itself, and then trying to infer properties and relations of A from properties
and relations that can be established about B.
This also holds in cases where the analogy is one of
kinds: The shapes of airplanes are determined in
part by experimentation in wind tunnels on small models (and the fact that
this works seems to show analogies in the flows of air around small objects
and much larger objects of the same form), and one's reactions to and
assessments of other persons depend to a considerable extent on the kind of
person they are deemed to be, and the inferences about such kinds of person
that are then applied to that specific person.