Defeasible logic is a
non-monotonic logic
A non-monotonic logic is a formal logic whose entailment relation is not monotonic. In other words, non-monotonic logics are devised to capture and represent defeasible inferences, i.e., a kind of inference in which reasoners draw tentative concl ...
proposed by
Donald Nute to formalize
defeasible reasoning
In philosophy of logic, defeasible reasoning is a kind of provisional reasoning that is rationally compelling, though not deductively valid. It usually occurs when a rule is given, but there may be specific exceptions to the rule, or subclasse ...
. In defeasible logic, there are three different types of propositions:
; strict rules : specify that a fact is always a consequence of another;
; defeasible rules : specify that a fact is typically a consequence of another;
; undercutting defeaters : specify exceptions to defeasible rules.
A priority ordering over the defeasible rules and the defeaters can be given. During the process of deduction, the strict rules are always applied, while a defeasible rule can be applied only if no defeater of a higher priority specifies that it should not.
See also
*
Common sense
Common sense () is "knowledge, judgement, and taste which is more or less universal and which is held more or less without reflection or argument". As such, it is often considered to represent the basic level of sound practical judgement or know ...
*
Default logic
References
* D. Nute (1994). Defeasible logic. In ''Handbook of logic in artificial intelligence and logic programming'', volume 3: Nonmonotonic reasoning and uncertain reasoning, pages 353–395. Oxford University Press.
* G. Antoniou, D. Billington, G. Governatori, and M. Maher (2001). Representation results for defeasible logic. ''ACM Transactions on Computational Logic'', 2(2):255–287.
Logic programming
Non-classical logic
{{compu-AI-stub