Whether an extorted promise be obligatory?

The Question must be considered as relating only to such promises as are unjustly extorted; for if reason approves of the claim, of a man, who is reduced to the necessity of employing violence to obtain it, she will undoubtedly likewise justify that violence. The laws of nature, and the customs of all civilized nations justify it. It cannot therefore be made a question: under the head of promises justly extorted, must be taken, all contracts with an open and public enemy, whether made by a nation at large, or, by individuals. A doubt can be raised therefore, only when the person by whom the promise is extorted, acts contrary to the Laws of nature and of nations, and I am sensible that most moral writers agree, that in cases of this kind, all promises, are null of themselves and consequently cannot be obligatory. As it would argue the most unjustifiable arrogance in me, to maintain an opinion in opposition to that of many persons, whose productions have done honour to human nature, I shall only beg leave, to question, whether the consequences which must attend the breach of extorted promises, might not be very prejudicial to the interests of mankind in general? And whether the man who should not prefer enduring, the greatest evils, even Death itself, rather than make a promise with the design never to fulfill it, would not be blameable for loosening the bonds of Society.