Natural Law

The disappearance of natural law arguments from mainstream philosophy was not nearly so abrupt in the nineteenth century as is often made out, as can be seen from the curricula and textbooks adopted at many universities. Nevertheless, the combined influence of Kantian idealism and utilitarianism did serve ultimately to undercut several of the key claims of the theorists of the preceding two centuries. In his Foundations of the Metaphysics of Morals (1785), Kant essentially generated a fresh account of moral obligation that was located not in the principles of human nature, but in an autonomous will freely exercising practical reason: Obligation lay not in the harmony of a principle with human nature, but in whether a law could be objectively generalized in relevantly comparable circumstances. Thus it appeared that natural law arguments only yielded empirical "counsels of prudence" about human behavior, not conceptually coherent moral yardsticks. A second blow was struck by Jeremy Bentham (1748–1832), who stressed that there was no "external consideration" that permitted natural jurisprudence to distinguish between one person's judgment of the law of nature and another's: natural law had to act as its own circular proof and guarantor, which was unacceptable. Attempts to distill a common set of principles from the infinite variety of the law of nations were bound to fail; he believed it to be far better to move outside the categories of reason and human nature altogether, accept the pluralist nature of human definitions of the good life, and reassert the supremacy of legal positivism, based on accommodating majority preferences. This point was particularly difficult for natural lawyers to answer, given that they had failed to observe how easily their view that knowledge of the law of nature was not reliant on God could slide into a statement that grounds for obeying natural law are not dependent on God either—a conclusion that left no clear criterion of obligation to fall back upon.

However, the eclipse of natural law arguments was by no means complete even at the beginning of the twenty-first century. While natural rights theories have pursued their own separate trajectory towards an assertion of the protection of individual rights as a good in itself, perhaps best embodied in the American philosopher Robert Nozick's Anarchy, State and Utopia, a number of Catholic theorists, most notably the Australian author John Finnis in Natural Law and Natural Rights, have reworked the idea of shared goods inherent in human nature, though the content of that list of shared goods and the relationship between them has proved to be controversial. As with the earlier versions of natural law theory that have taken their stand on human nature and its attributes, this version too stands or falls on the richness or poverty of its conception of that human nature, and on the clarity and self-awareness with which human nature is neutrally described or prescribed in relation to other norms at each step in the argument. All such theories explore very difficult philosophical territory because they seek to unify two essentially different projects: to provide specific prudential advice on how best to achieve one's objectives (implying a recognition that human nature and its needs change in line with historical circumstances in ways that reason alone does not always fully comprehend), together with a parallel recognition that for human insights to be generalized as valid law, they need to be assessed according to a sole and unvarying standard, usually identified as rational truth. Those thinkers who have best overcome these paradoxes, such as the Stoics, Grotius, and Pufendorf, lived in periods of significant social dislocation, but were stimulated to identify and narrow general principles attributable to reason that were also imaginatively rich enough to meet the shifting empirical shoals of their own political and existential crises. That is why they are still worth studying in the twenty-first century, for this juxtaposition of moral philosophy with moral exigencies is a task that is never completed, despite the shift in intellectual frameworks that makes the natural law era seem so distant and different from that of the present.