In his political discourse ‘Of Public Credit’, first published in 1752, David Hume delivered a judgement striking in its menace and severity: ‘either the nation must destroy public credit, or public credit will destroy the nation’. What did he mean?

In John Pocock's suggestive and elegant argument, his judgement was an expression of an inescapable ambivalence in Hume's vision of commercial modernity. For Hume commerce was an essentially positive agency in world history, the handmaid of modern liberty and source of modern civilisation. Pocock suggests that in the Humean macrocosm commerce was to modern politics what, in Montesquieu's language, virtue was to republics: its ‘principle’. As it was the ‘inner meaning of the republican thesis that virtue must sustain the conditions necessary to virtue’, commerce, in order to carry the weight heaped on it by Hume's theory of modernity, had to have the same self-preserving qualities. Tragically, as Hume himself realised (Pocock tells us), this was not the case, for commerce met its nemesis in the public debt. An agent of thoroughgoing corrosive power, public debt was created by the commerce it would eventually destroy.

Although on Pocock's account public credit and the expansion of trade are ‘logically separable’, he reads Hume's essay as conjuring up ‘a vivid image of a society destroying itself by heaping up the public indebtedness to the point where trade and agriculture were both brought to ruin’.