Hume held that shared perceived self-interest, not morals, first obliges promise-keeping.

Evidence

Hume made the case for this process absolutely clear: When each individual perceives the same sense of interest in all his fellows, he immediately performs his part of any contract, as being assur’d that they will not be wanting in theirs. All of them, by concert enter into a scheme of actions, calculated for common benefit, and agree to be true to their words; nor is there anything requisite to form this concert or connection, but that every one have a sense of interest in the faithful fulfilling of engagements, and express that sense to other members of the society. This immediately causes that interest to operate upon them and interest is the first obligation to the performance of promises. Afterwards a sentiment of morals concurs with interest, and becomes a new obligation upon mankind (1969: 574). — Diego Gambetta, Trust - Making and Breaking Cooperative…, 2796

Categorization

• DEFINE: Defines the Humean mechanism where expressed common interest precedes moral obligation — a precise conceptual anchor for the reader’s trust analysis.
• XREF: Connects to the reader’s own source on pre-state law-merchant reputation systems, where mutual interest sustained honesty before institutions. — connects to: Locke’s natural man is political and moral before property makes him self-interested. — Wendy Brown, Undoing the Demos: Neoliberalism’s…, 187