A young scientist and mathematician explores the mystery and complexity of human thought processes from an interdisciplinary point of view.

This paper discusses the functions of deductive justification in ideal reconstructions of judicial reasoning. It departs from the point of judicial reasoning: explaining and justifying the judicial decision. It argues that deductive validity is not enough for good judicial argument. On the other hand, deductive justification is necessary, not only for easy cases but for hard cases as well. It draws some consequences for the concept of ‘jumps’ in legal reasoning and for the traditional distinction between internal and external justification.