[From] Elements of Natural Law, by Leibniz
[How to] demonstrate the necessary connections between things by deducing them from a clear and distinct intuition through a series of definitions …
Gottfried Wilhelm Leibniz [1646-1716] wrote:
1. The doctrine of Right belongs to those sciences which depend on definitions and not on experience and on demonstrations of reason and not of sense; they are problems of law, so to speak, and not of fact. For since justice consists in a kind of congruity and proportionality, we can understand that something is just even if there is no one who practices it or upon whom it is practiced. Just so the relations of numbers are true even if there were no one to count and nothing to be counted, and we can predict that a house will be beautiful, a machine efficient, or a commonwealth happy, if it comes into being, even if it should never do so. We need not wonder, therefore, that the principles of these sciences possess eternal truth. For they are all conditionalia, conditional truths, and treat not of what does exist but of what follows if existence be assumed. They are not derived from sense but from a clear and distinct intuition [imaginatio], which Plato called an idea, and which, when expressed in words, is the same as a definition. That which can be understood clearly, however, is not always true, though it is always possible; and it is also true, in addition, whenever the only question is that of possibility. But whenever there is a question of necessity, there is also one of possibility, for if we call something necessary, we deny the possibility of its opposite. It therefore suffices to demonstrate the necessary connections between things and their consequences in this way: by deducing them from a clear and distinct intuition (that is, from a definition when this intuition is expressed in words), through a continuous series of definitions which imply them; that is, through a demonstration. Therefore since the doctrine of Law is a science, and the basis of science is demonstration, and definition is the principle of demonstration, it follows that we must first of all investigate the definitions of the words Right, just, and justice, that is, the clear ideas by which we usually estimate the truth of propositions or of the right use of words in speech, even when we do not know we are doing so.
2. The method of our investigation is to gather the more important and distinctive examples of the use of these terms and to set up some meaning consistent with these and other examples. For just as we construct a hypothesis by induction from observations, so we construct a definition by comparing propositions; in both cases we make a compendium of all other instances, as yet untried, out of the most important given cases. This method is necessary whenever it is not desirable to determine the use of terms arbitrarily for one's self. For as long as we are speaking only to ourselves or to our special group, or about something not generally known, it is in our power to assign to any definite idea whatever the word which will serve to arouse our memory, so that it will be unnecessary for us always to repeat the definition, that is to say, ten other words. But when we are writing for the public and on a commonly discussed matter in which we do not lack terms, it is either the folly of one who does not want to be understood, or the malice of a deceiver, or the pride of one who seeks to bring others to his own views without offering any reasons, to think up words or usages private and peculiar to one's self.
The Source:
Gottfried Wilhelm Leibniz, ‘Elements of Natural Law’ [1670-71], in Gottfried Wilhelm Leibniz, Philosophical Papers and Letters, A Selection Translated and Edited, with an Introduction by Leroy E. Loemker, Kluwer Academic Publishers, 1989
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