Full Idea
Grue cannot be a relevant kind for induction in the same world as green, for that would preclude some of the decisions, right or wrong, that constitute inductive inference.
Gist of Idea
Grue and green won't be in the same world, as that would block induction entirely
Source
Nelson Goodman (Ways of Worldmaking [1978], 1.4b)
Book Reference
Goodman,Nelson: 'Ways of Worldmaking' [Hackett 1984], p.11
A Reaction
This may make 'grue' less mad than I thought it was. I always assume we are slicing the world as 'green, blue and grue'. I still say 'green' is a basic predicate of experience, but 'grue' is amenable to analysis.