Defeasibility, Contributory Conditionals, and Refinement of Legal Systems*

Juliano S.A. Maranhão

in The Logic of Legal Requirements

Published in print September 2012 | ISBN: 9780199661640
Published online January 2013 | e-ISBN: 9780191745461 | DOI:
Defeasibility, Contributory Conditionals, and Refinement of Legal Systems*

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This chapter takes up with Alchourrón's well-known attack against nonmonotonic logics. It surveys Alchourrón's convictions about legal epistemology and argues that they provided the impetus for his opposition to nonmonotonic logics. It also proposes the view that Alchourrón's approach to defeasibility leaves three important aspects aside, which seem to have been endorsed in his final writings: that the legal system is a set of strict conditional rules which is subject to change into a system containing more refined strict conditional rules; that within the normative system explicit norms have different epistemic status than derived ones (not all derived norms are valid); and that the defeat results from a creative intervention by the interpreter changing the system of rules into a more qualified and consistent system. The chapter introduces a specific revision operator, called refinement, which is taken to capture these neglected aspects and provides better representation of the so-called ‘epistemic conception’ of legal defeasibility.

Keywords: nonmonotonic logics; Alchourrón; legal epistemology; legal system; conditional rules; refinement; legal defeasibility

Chapter.  13867 words. 

Subjects: Jurisprudence and Philosophy of Law

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