Pufendorf: On the Duty of Man and Citizen according to Natural Law

1. It is certainly true that one's Obligation in matters enjoined by authority is limited to what the authority intended, just as one's own voluntary commitments extend no further than one's intention. But a man cannot teil another man's will except from acts and signs apparent to his senses. Hence one's obligations, so far as human judgement goes, are held to consist in what a correct interpretation of the signs indicates. It is therefore a great contribution to a proper understanding of laws and agreements, and of doing one's duty on the basis of them, to draw up rules of sound interpretation, and particularly the interpretation of words, since words are the commonest signs.

2. The rule about words in common use is: words are normally to be taken in their own proper and accepted sense, the sense which they have not so much from strict propriety or grammatical analogy or similarity of derivation as from common usage. ‘Common usage is the arbiter, the law and the norm of Speech.'

3. Terms of art are to be explained according to the definitions of the experts in each art. But if terms of art are differently defined by different experts, it will tend to avoid disputes if we express in ordinary words what we understand by any particular term.

4. Conjectures are needed to extract the real meaning, if words or expressions are ambiguous, or if certain parts of a piece seem to contradict each other, provided that they can be reconciled by skilful exegesis. For where there is a certain and obvious contradiction, the later passage supersedes the earlier.

5. Conjectures about the intention and correct sense of an ambiguous or intricate passage are made on the basis of subject-matter, effect and related passages.

The rule on subject-matter is: words are normally to be understood in the light of the subject. For the Speaker is presumed always to have in mind the subject of his discourse; and therefore the meanings of the words should always be appropriate to it.

6. The rule on effect and consequences is: if the words taken in a simple, literal sense would have no effect or an absurd effect, one should diverge from the commonly accepted sense only so far as is necessary to avoid meaninglessness or absurdity.