 Instead of taking social categories to be products of individual minds, another class of theories holds that they are the products of the minds in a community taken together. Hume 1740 argues that promises are a product of a social convention. We have a convention, according to Hume, of the following form: words uttered according to a certain formula incur an obligation. When someone utters a phrase of the form ‘I promise to S’, the speaker is obligated to perform S. According to this theory, the conditions for an utterance to be a promise are set up by beliefs and expectations of the members of the community at large.