Organization of ideas in Anglo-American private law has been beset with difficulties – linguistic, philosophical, jurisprudential, rhetorical, and historical. This study, though not a history of private law (by period or by topic), is historical in perspective: attention is directed to the past (from the eighteenth century to the recent past), and to the failure of any organizational scheme or of any single or simple explanation either to describe the law that preceded it, or to supply a workable guide for decisions thereafter. This failure suggests that the interrelation of legal concepts has involved a greater complexity than can be captured by organizational schemes, maps, or diagrams, or by any single explanatory principle.

Since the nineteenth century it has been common to make distinctions in respect of Anglo-American law between public and private law, and within private law between property and obligations, and within obligations among contracts, torts, and unjust enrichment. Legal issues and rules have been supposed to belong to one of these subcategories, and the rules applied to determine the result in particular cases. But this scheme has failed to account for many actual judicial decisions, a failure that led, in the twentieth century, to scepticism of formal explanations of law, to alternative explanations, and in turn to counter-reaction.

This study approaches these questions not by proposing any new all-embracing explanation, or by seeking to impose a single pattern on all of private law, but by proceeding from the particular towards the general.