Retroduction

Part of speech: noun

Definitions

1. A type of logical reasoning that reverses from an established conclusion to uncover the premises that support it
2. A method of deduction that traces back from a conclusion to identify the original reasons or causes that led to it
3. A form of reasoning that starts from a conclusion to determine the underlying assumptions or principles that justify it

Etymology: Retroduction is a term from the logic of C. S. Peirce, the American philosopher who used it for a kind of reasoning he distinguished from deduction and induction. The Latin "retroducere" combined "retro," meaning backward, with "ducere," meaning to lead, so the word literally describes leading something back to its source. That fits the method exactly: one starts with a result already observed and works backward to the hypothesis that would have to be true for that result to follow. The Latin parts are old and ordinary, but the English noun is a specialized coinage of logic, not a word that passed through daily speech. Its surprise lies in the reversal it describes: where a deduction moves forward from premises to a certain conclusion, retroduction runs the path the other way, reaching for the assumptions behind a conclusion that is already in hand.

Synonyms: inference, deduction