Wednesday, September 21, 2011

Thomas Kuhn: "Metaphor in Science" (1979)

There's a nice little paper by Thomas Kuhn in the book Metaphor and Thought, edited by Andrew Ortony. The paper in an exercise in Wittgensteinian pragmatism with special applications to new, "metaphorical" usage patterns.

Kuhn begins by endorsing an observation:
However metaphor functions, it neither presupposes nor supplies a list of the respects in which the subjects juxtaposed by metaphor are similar. (p. 533)
Rather, he says, a metaphor works by "creating or calling forth the similarities." (p. 533)

His main example throughout the paper is the word planet:
The moon belonged to the family of planets before Copernicus, not afterwards; the earth to the family of planets afterwards, but not before. Eliminating the moon and adding the earth to the list of individuals that could be juxtaposed as paradigms for the term "planet" changed the list of features salient to determining the referents of that term. Removing the moon to a contrasting family increased the effect. (p. 540)
His idea thus rests on a theory of meaning that sometimes sounds a bit like a Bayesian learning algorithm, with the social environment providing a classified set of frequently occuring examples:
Exposed to tennis and football as paradigms for the term "game," the language learner is invited to examine the two (and soon, others as well) in an effort to discover the characteristics with respect to which they are alike (p. 537).
After having learned a term this way, the learner will probably have an easier time categorizing soccer than fencing or professional boxing, as Kuhn notes (p. 536).

The learning algorithm is in any event probably more efficient if it includes negative as well as positive evidence. Kuhn briefly mentions that wars, for instance, are not games, irrespective of the similarities they might have (p. 536).

The paper also explicitly refers to his other nice disccusion of meaning and categorization, the article "Second thoughts on paradigms," which is printed in The Essential Tension (1977).

That's the one in which he writes that "anything is similar to, and also different from, anything else" (p. 307) and argues that you can't learn the meaning of the term duck without acquiring some knowledge and beliefs about ducks as well.

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