Defeasible logic is a
non-monotonic logic
A non-monotonic logic is a formal logic whose conclusion relation is not monotonic. In other words, non-monotonic logics are devised to capture and represent defeasible inferences (cf. defeasible reasoning), i.e., a kind of inference in which re ...
proposed by
Donald Nute to formalize
defeasible reasoning
In philosophical logic, defeasible reasoning is a kind of reasoning that is rationally compelling, though not deductive reasoning, deductively valid. It usually occurs when a rule is given, but there may be specific exceptions to the rule, or su ...
. 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 a 47-page pamphlet written by Thomas Paine in 1775–1776 advocating independence from Great Britain to people in the Thirteen Colonies. Writing in clear and persuasive prose, Paine collected various moral and political arg ...
*
Default logic Default logic is a non-monotonic logic proposed by Raymond Reiter to formalize reasoning with default assumptions.
Default logic can express facts like “by default, something is true”; by contrast, standard logic can only express that somethi ...
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