The New Riddle
The problem, known as Goodman's paradox, is as follows. A standard example of induction is this: All emeralds examined thus far are green. This leads us to conclude (by induction) that also in the future emeralds will be green, and every next green emerald discovered strengthens this belief. Goodman observed that (assuming t has yet to pass) it is equally true that every emerald that has been observed is grue. Why, then, do we not conclude that emeralds first observed after t will also be grue, and why is the next grue emerald that comes along not considered further evidence in support of that conclusion? The problem is to explain why induction can be used to confirm that things are "green" but not to confirm that things are "grue".
Goodman's solution to the problem regarded a term's reference to time, or definition in relation to time. Since variation of such definitions is a language-relative matter, a term's clarity of meaning, depending on the original language, would vary the quality of the induction's conclusion. Therefore, terms like "grue" should be left out of induction.
Read more about this topic: Grue And Bleen
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