Defeasible Reasoning - Political and Judicial Use

Political and Judicial Use

Many political philosophers have been fond of the word indefeasible when referring to rights, e.g., that were inalienable, divine, or indubitable. For example, in the 1776 Virginia Declaration of Rights, "community hath an indubitable, inalienable, and indefeasible right to reform, alter or abolish government..." (also attributed to James Madison); and John Adams, "The people have a right, an indisputable, unalienable, indefeasible, divine right to that most dreaded and envied kind of knowledge - I mean of the character and conduct of their rulers." Also, Lord Aberdeen: "indefeasible right inherent in the British Crown" and Gouverneur Morris: "the Basis of our own Constitution is the indefeasible Right of the People." Scholarship about Abraham Lincoln often cites these passages in the justification of secession. Philosophers who use the word defeasible have historically had different world views from those who use the word indefeasible (and this distinction has often been mirrored by Oxford and Cambridge zeitgeist); hence it is rare to find authors who use both words.

In judicial opinions, the use of defeasible is commonplace. There is however disagreement among legal logicians whether defeasible reasoning is central, e.g., in the consideration of open texture, precedent, exceptions, and rationales, or whether it applies only to explicit defeasance clauses. H.L.A. Hart in The Concept of Law gives two famous examples of defeasibility: "No vehicles in the park" (except during parades); and "Offer, acceptance, and memorandum produce a contract" (except when the contract is illegal, the parties are minors, inebriated, or incapacitated, etc.).