Grue and Bleen / The New Riddle of Induction
Updated 2026-08-01
INTRODUCTION
English translation pending.
CORE DEFINITION
Introduced by Nelson Goodman in Fact, Fiction, and Forecast. An object is grue if it is examined before a future time t and found green, or examined after t and found blue; bleen is the mirror image. Before t every examined emerald confirms both the hypothesis that all emeralds are green and the hypothesis that all emeralds are grue, yet the two predict different colours after t. Goodman's point is that no purely formal rule of confirmation distinguishes them, so the difference must lie in which predicates are entrenched in our language and practice. This is the new riddle of induction, distinct from Hume's problem of justifying induction at all.
SCAFFOLDING EFFECT
Reduce cognitive load
- Hypothesis testing: Ask which rival predicates fit your existing data just as well as your own. - Prediction audit: Check whether a forecast depends on a cut-off date the data itself cannot reveal. - Definition scrutiny: Distinguish natural categories from definitions engineered backwards to fit the past.
Anchor fast decisions
Confirmation is a relation between evidence and a hypothesis, and both green and grue are satisfied by every observation made so far. What separates them is not logic but projectability: some predicates are entrenched by long use in successful inductions and others are not. Because entrenchment comes from practice rather than from evidence, every forecast relies on a background choice the data alone cannot justify. The riddle shows that induction needs a theory of which predicates are fit to project.
MINIMUM ACTION
In progress 0/1Practice this model in one real situation:
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Source support: Explicit
- en.wikipedia.orghttps://en.wikipedia.org/wiki/New_riddle_of_inductionverified
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