Must a Promise Made Under Threat Be Kept?

Suppose someone threatens to publish your private information unless you promise to pay them every week. You did say, “I promise”, yet it is difficult to claim that those words created an ordinary promissory obligation. A promise changes what people owe one another not merely because certain sounds were made, but because the promisor can use their own judgement to give another person an assurance. A wrongful threat manipulates that very condition.

In Book III of the Nicomachean Ethics, Aristotle describes actions taken under grave threats as “mixed”. The agent chooses the action at the time and is therefore not involved in the same way as someone physically carried off by the wind; yet apart from the threat, they would not choose the action for its own sake. Contemporary theories of coercion continue to dispute how severe a threat must be, which baseline determines whether freedom has been reduced, and how a permissible warning differs from a wrongful threat.

My view is that a coercer cannot first create an option that ought not to exist and then treat the victim’s submission as the source of a new right. In this example, stopping the payments would not normally be a breach of faith. Still, saying the promise is not binding does not erase every responsibility. If the victim later induced an innocent third party reasonably to rely on the words, or had a safe opportunity to seek help and limit losses, those further duties must be considered separately. What matters is not simply whether the sentence was spoken, but whether it arose from an accountable choice not wrongfully controlled by another.

https://plato.stanford.edu/entries/coercion/
https://classics.mit.edu/Aristotle/nicomachaen.3.iii.html