… I want in this paper to challenge this view by showing that the relationship between promises and the obligations they generate is not a conceptual or definitional relationship. In contrast, there is a logical gap between the making of a promise and the incurring of a promissory obligation. This is partly because the question whether, in given circumstances, a promise has in fact been made is a merely empirical question and the question whether, thereby, a promissory obligation has been generated is an expressly normative question. It is also partly because an affirmative answer to the empirical question, while essential to establishing an affirmative answer to the normative question, is not all that it takes to determine whether a promissory obligation has been generated: various expressly normative conditions must also be satisfied …
Alistair M Macleod, Promises and Promissory Obligations [or When Is There No Obligation to Keep a Promise?], Journal of Social Philosophy. First published: 26 December 2019. https://doi.org/10.1111/josp.12323.