What is “law”? In a forthcoming essay, Brian Leiter provides an excellent summary of H.L.A. Hart’s influential “legal positivist” theory of law. In addition, Professor Leiter, a philosopher of law at the University of Chicago, claims that Hart’s account of legal positivism has three advantages over competing theories: (1) Hart’s theory provides a common sense or plausible account of the ordinary man’s understanding of law, (2) it can be tested empirically, and (3) it is parsimonious. Unfortunately, Leiter is flat out wrong on all three counts. Let’s examine each of his claims in turn:
First and foremost, if we are looking for a theory that best captures the ordinary man’s understanding of law, we need look no further than Oliver Wendell Holmes’s famous but now unfashionable bad man theory of law, which Holmes enunciated in his classic work “The Path of the Law,” published in 1897. Hart’s theory of legal positivism, by contrast, requires us to posit a circular and quasi-mystical entity: the so-called “internal point of view.” Since so many others have covered this well-worn theoretical ground before, suffice it to say the internal point of view is circular because it simply assumes what we are trying to explain (i.e. what is law?), and it is quasi-mystical because it requires us to figure out what is going on within the inner recesses of the minds of certain legal officials.
Secondly, contrary to Professor Leiter’s overblown claims, legal positivism is not really empirically testable in any meaningful or Popperian sense. Unlike Holmes’s bad man theory of law, which can be tested (since we can, in principle, measure rates of legal compliance and evasion), Hart’s theory requires us to survey the multifarious and possibly contradictory motives of certain persons for accepting the legal system. More fundamentally, we would argue that the many competing theories of legal positivism as well as natural law theories are just a world view or paradigm (to borrow from Thomas Kuhn’s influential theory of scientific revolutions), a way of looking at the law tout court. Accordingly, like aesthetic, moral, or religious beliefs, no amount of evidence or research will persuade one to change one’s world view, even if you’re a bayesian.
Lastly, legal positivism is not as parsimonious as Professor Leiter would have us believe. By way of example, according to Leiter, Hart’s own theory is premised on two separate ideas, what Leiter labels the Sources Thesis (or in the words of Leiter, the idea that “norms are legally valid only in virtue of having certain sources … without regard for their merits”) and the Conventionality Thesis (the idea that “the relevant sources of law in each society are fixed by a contingent practice of officials of the legal system”). Other legal theorists, like Richard Holton, claim that legal positivism is premised on three separate theses, not two. Whatever the case, my point here is not to rehash the central tenets of legal positivism. My point is simply that legal positivism is not so parsimonious at all once one delves into the intricate details of Hart’s theory. (Again, if it’s parsimony we’re after, Holmes’s bad man theory of law provides the most parsimonious explanation of law.)