The Moral Sense of Right and Wrong: the Notion of Punishment
Criminal law was clearly not at the forefront of Kames's interests. And yet, some of the most central passages that defined the concept of conjectural history of the Scottish Enlightenment are in a single piece Kames wrote on criminal law, the first of the Historical Law-Tracts (1758) and the only text in his large oeuvre specifically devoted to criminal law.
We have encountered Kames as a fierce advocate for a legal science, which entails logical reasoning, systematisation, an idea of a rule of law and, nowadays, precise definition and labelling of criminal offences, exact rules of interpretation based on rational principles – all that to avoid arbitrariness of court decisions, since ‘judges ought to be confined to general rules, the only method invented to prevent legal oppression’. But Tract I on criminal law contains nothing of that sort, in particular no theoretical-doctrinal discussion of which is now called the ‘General Part’ of the criminal law: the general rules and principles of criminal law which apply not to specific crimes but to crimes in general, such as the state of mind (intention/recklessness), acts and omissions, causation, defences, accessories to crimes. Kames did not venture to develop a scheme of classification for Scots criminal law either. This was left to Kames's protégé, John Millar, who provided in his (unpublished) lectures a classification of Scots criminal law, based on Adam Smith's Lectures on Jurisprudence (then unpublished), and Erskine's Principles of the Law of Scotland (1754) and his Institute which appeared only in 1773. Hence Kames does not discuss the possible codification of criminal law either, a topic that was much debated and promoted in the latter half of the eighteenth century.
When Kames wrote about criminal law in the 1750s, there was not much literature on Scots criminal law Kames could have drawn from for any possible doctrinal studies: Mackenzie's Laws … in Matters Criminal (1678) was becoming out of date both in substance and style, law reporting of criminal cases was sketchy, but there was a short textbook on criminal law by the professor of Scots law in Edinburgh, Alexander Bayne, published in 1730.