Ethics, Part IV, Proposition 72
The free man never acts fraudulently, but always in good faith.
Proof
If it be asked: What should a man's conduct be in a case where he could by breaking faith free himself from the danger of present death? Would not his plan of self--preservation completely persuade him to deceive? This may be answered by pointing out that, if reason persuaded him to act thus, it would persuade all men to act in a similar manner, in which case reason would persuade men not to agree in good faith to unite their forces, or to have laws in common, that is, not to have any general laws, which is absurd.
Benedict de Spinoza, The Ethics (Ethica Ordine Geometrico Demonstrata), translated from the Latin by R. H. M. Elwes.
First published in The Chief Works of Benedict de Spinoza, vol. II (London: George Bell and Sons, 1884).
This translation is out of copyright in the United States, where it was published in 1884, and wherever the copyright term is the author's life plus 100 years or less; its translator died in 1892.
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