Vol 18 No 1 (2018)
Logic and Law

Los Fundamental principles of logic applied in Law

Giovanni Battista Ratti
Istituto Tarello per la Filosofia del Diritto, Genoa University
Jorge L. Rodríguez
Faculty of Law, Mar del Plata state university
Published July 22, 2018
  • Law,
  • Logic,
  • Principle of identity,
  • Consistency,
  • Completeness


According to some authors (that we can dub “Believers”), some fundamental principles of logic, such as the principle of non-contradiction and the law of excluded middle, are also valid in their normative transposition into the legal domain. Based on such a view, they maintain that logic allows one to justify that legal systems are necessarily complete and consistent. Contrariwise, some authors (dubbed “Skeptics”) argue that legal systems are commonly affected by inconsistencies and gaps, and this is a reason to maintain that we have to deny that norms have logical relations. According to these authors, this also implies that, in general, logic cannot play any significant role in analyzing the law. In this paper, we show that this is a false dilemma. Far from being intrinsic to law, logic cannot justify that legal systems lack defects such as gaps or inconsistencies. However, it is logic what provides us with an unavoidable and powerful toolbox, which allows us to demystify the idea that law is a complete and consistent whole.