Adam Smith and Jean-Jacques Rousseau agree that justice is the cornerstone of society, and they disagree in their appraisal of commercial society on the grounds of justice. Their disagreement goes beyond their beliefs about whether justice can be achieved or not in this society: it has to do with what exactly they understand by the term ‘justice’, and which sense of justice they consider indispensable for social order. In general, justice has to do with the regulation of social interactions, but looking into the details of this allows us to understand that there are different types of justice, which entail different kinds of regulations.

Even if neither of them accomplished their avowed project of completing a whole system of jurisprudence (Hanley 2008a), both Rousseau and Smith thought it was of the utmost importance for the good government of a well-ordered society. Smith considered natural jurisprudence to be the most important part of the science of ethics for social order, as it aims at establishing precise rules for behaviour, and in particular deals with the study of justice, ‘the only virtue with regard to which such exact rules can be properly given’ (TMS VII.iv.7: 329–30). These rules guarantee the preservation of society because without justice ‘the fabric of human society … must in a moment crumble into atoms’ as ‘a man would enter an assembly of men as he enters a den of lions’ (TMS II.ii.3.4: 86). Along the same lines, Rousseau gives justice a fundamental role in promoting the greatest good for all, that is, freedom and equality for all citizens as members of the general will (DCS OC III: 391). In his Lettres écrites de la montagne he says ‘the first and greatest interest of the public is always justice. They all want conditions to be the same for all, and justice is this equality’ (OC III: 891). Justice and truth, according to Rousseau, are the first duties (Lettre à M. d’Alembert OC V: 3) of citizens so they may enjoy their rights (DCS OC III: 363).