I. Kant and Lon L. Fuller: On the Rule of Law

Abstract

I. Kant and Lon L. Fuller are rarely considered like-minded thinkers. However, to portray this intellectual affinity, I will lay out, firstly, the specific requirements of the internal morality of law as presented by Lon L. Fuller in The Morality of Law (1964) in reference to monarch Rex. Secondly, I will compare three of the fundamental requirements of the internal morality of law (the generality of law, the promulgation, and non-retroactivity of law) with I. Kant’s reflections, as developed in his “Doctrine of Right” from the Metaphysics of Morals (1797), about public justice and criminal law. Finally, I will reinforce the outcome of the two previous sections and highlight the intellectual affinity between both authors regarding a specific and peculiar requirement of the internal morality of law, namely, that legal rules must prescribe to its recipients something possible. I will propose interpreting this requirement from I. Kant’s concept of the law of humanity.