Both the history of tort law and the recent theoretical literature on the subject suggest that there are two intellectually tenable and more or less equally respectable answers to the question of what should be the general standard of liablity in tort, namely fault and strict liability. Each is generally thought to have represented, at one time or another, the dominant approach of the positive common law. Each has its modern theoretical proponents: a fault-based approach has been argued for on grounds of economic efficiency by Richard Posner, for example, and on grounds of individual moral right by, among others, Ronald Dworkin and Ernest Weinrib; strict liability, on the other hand, has received an economic defence in the work of Guido Calabresi, and a rights-based defence in the writings of Richard Epstein. Each of these theorists has felt compelled not only to offer positive arguments in favour of fault or strict liability but also to answer the intellectual case, whether perceived as being founded on a conception of efficiency or of individual rights, for the rival approach.