Logic of Legal Reasoning

Abstract

This article deals with general problem of connection between legal reasoning, legal argumentation and, on the other hand, logic. Although this connection seems obvious since ancient times, its nature is still the subject of non-trivial discussions. The purpose of my study is to explore one important aspect of this connection, namely, is general, or formal, logic necessary and sufficient to determine relevant form of legal reasoning and argumentation? To reach this purpose, method of comparative analysis is employed both synchronically and diachronically. First, in order to prove importance of the issue, a diachronic comparison of several basic approaches is carried out (G.W. von Leibniz, O.W. Holmes, Jr., etc.). Then a comparative analysis of the views of some contemporary experts is carried out, especially Ilmar Tammelo and Stephen Toulmin. It is argued, in the field of law there is a special legal validity that differs significantly from the formal-logical validity. The legal validity is determined directly and mainly by the value of the right not by the value of formal or material truth. It is not the subject of formal logic, but of a special legal logic and, more broadly, informal logic. Therefore, formal logic does not determine relevant form of legal reasoning and argumentation, since, first of all, there is the essential difference between the formal-logical validity and the legal validity. It is argued, formal logic is neither sufficient nor necessary to think like a jurist. In this regard, it is shown that the formal-logical standard of proof is not sufficient to determine the relevant form of valid legal proof. There are at least three standards of legal proof – proof without reasonable doubt, proof by clear and convincing evidence, and proof by preponderance of the evidence. Each of them differs significantly from the formal-logical standard. The conclusion of this research is this: it cannot be said that general logic does not work at all in the field of law. However, in order to reason and argue like a successful jurist, one must to grasp and use, without any exceptions, the special legal logic that belongs to the domain of contemporary informal logic.