AskDefine | Define indefeasible

Dictionary Definition

indefeasible adj : not liable to being annulled or voided or undone; "an indefeasible right to freedom"; "an indefeasible claim to the title" [ant: defeasible]

User Contributed Dictionary



  1. not capable of being defeated or penetrated


Extensive Definition

Defeasible reasoning is the study of forms of reasoning that, while convincing, are not as formal and rigorous as deductive reasoning. It has been discussed in philosophy and, more recently, in artificial intelligence.
Other alternatives to deductive reasoning include inductive reasoning and retroductive reasoning. These are not traditionally covered by most uses of the term "defeasible reasoning".

Origins in philosophy

Though Aristotle differentiated the forms of reasoning that are valid for logic and philosophy from the more general ones that are used in everyday life (see dialectics and rhetoric), subsequent philosophers mainly concentrated on deductive reasoning.
It wasn't until logical positivism started falling out of favour that philosophers like Roderick Chisholm and John L. Pollock renewed an interest in defeasible reasoning.

Artificial intelligence

Around the same time period, developments in artificial intelligence led pioneers like John McCarthy and Patrick J. Hayes to represent a form of defeasible reasoning as they encountered the frame problem and the qualification problem.
Several forms of defeasible reasoning were proposed:
indefeasible in Chinese: 可废止推理

Synonyms, Antonyms and Related Words

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