Smith discusses Spooner’s secular theory of natural law and his belief that no legislation is valid unless it conforms to natural law.

George H. Smith was formerly Senior Research Fellow for the Institute for Humane Studies, a lecturer on American History for Cato Summer Seminars, and Executive Editor of Knowledge Products. Smith’s fourth and most recent book, The System of Liberty, was published by Cambridge University Press in 2013.

In his insightful book, Slavery and Anti‐​Slavery: A History of the Great Struggle in Both Hemispheres; With a View of the Slavery Question in the United States (1852), the abolitionist William Goodell noted that “a very small proportion of [American] abolitionists, if any, at the present time, occupy precisely the original ground” that they did 20 years earlier, when the movement began in earnest. Changes of opinion ranged from whether abolitionists should support women’s rights, to how proslavery churches should be dealt with by abolitionists, to the practicality of supporting a political party devoted exclusively to abolishing slavery, to whether abolitionists should embrace pacifism and thereby repudiate all compulsory governments, to whether abolitionist organizations and newspapers should endorse social and political reforms other than abolishing slavery, to whether political candidates who merely opposed the extension of slavery rather than its abolition deserve the votes of political abolitionists.

One of the most important controversies was whether the U.S. Constitution should be interpreted as a proslavery or as an antislavery document. This was a crucial controversy, for on it depended a key issue of strategy, namely, whether abolitionists could in good conscience vote and engage in other political activities. Only if the Constitution were an antislavery document, or at least neutral in this regard, could an abolitionist honestly swear to uphold the Constitution—an oath that was a precondition of assuming political office. Nor could an abolitionist vote for another person to act as his agent and take the same immoral oath. (As I explained in previous essays, this anti‐​political position is generally known as Garrisonianism, after William Lloyd Garrison, though Wendell Phillips defended it more thoroughly than Garrison did.)

William Goodell (p. 454) described how some abolitionists changed their minds on the constitutionality question.

Some, on investigation, changed their views of the Federal Constitution, and, believing it to contain no “guaranties” of slavery, but a distinct guaranty of free institutions, they could no longer continue to concede those pro‐​slavery guaranties, but, on the other hand, demanded that the “guaranty” of Republican State Governments should be redeemed, and rendered available.

Some changed their views of the Constitution in the opposite direction—perhaps changed twice;—repudiating, in the first place, “the compromises,” and holding the Constitution (as did N.P. Rogers) to be thoroughly anti-slavery—and then (assenting to the pro‐​slavery construction) denouncing it, very consistently, as a “covenant with death, and an agreement with hell.”

Goodell agreed with Lysander Spooner that the Constitution, properly understood, is antislavery. In 1845—shortly before Spooner published the first part of The Unconstitutionality of Slavery—Goodell defended this position in American Constitutional Law in its Bearing upon American Slavery. Despite reaching the same conclusion, Goodell later claimed that he and Spooner differed significantly in how they reached this conclusion: Spooner relied on legal technicalities, whereas Goodell grounded his arguments in first principles. This was scarcely a fair representation of Spooner’s arguments, which were based on natural law and natural rights; these played essential roles in Spooner’s theory of constitutional interpretation. But there was a significant difference nonetheless. The Christian Goodell located the ultimate foundation of natural law and natural rights in the will of God. As he wrote in American Constitutional Law, “There is neither legitimate authority, nor binding precedent, nor valid law, except in harmony with His will.”

Spooner, in contrast, was a deist who rejected all forms of revealed religion. He based his theory of natural law and natural rights on the nature of man and on the necessary conditions of peaceful social interaction. Of course, since deists believed in a creator God, they agreed with Christians that God created human nature as it presently exists, but they did not believe that our obligation to obey the precepts of natural law flows from the will of God. Something is not good because a god wills it to be so. A natural‐​law moral principle is good because, based on the nature of man, it is good for human beings. Moreover, as the qualifier “natural” also suggests, natural‐​law principles are knowable to man’s natural faculties. We may know the principles of justice through reason alone, without appealing to God’s will through the Bible, divine inspiration, or some similar means. This deistic reliance on reason alone meant that Spooner could not weaken the logical unfolding of his theory of justice by citing biblical injunctions to obey governments, nor could he possibly view government as a divinely mandated institution. Free of the potential obstacles posed by revealed religion (especially the Bible), Spooner pushed his theory of natural law and natural rights as far as reason would take him; and this imparted a radical, anarchistic edge to his political theory that most of his classical liberal colleagues (including many abolitionists) and predecessors were unwilling to accept.

Spooner opened The Unconstitutionality of Slavery with a chapter on natural law. A more complete discussion appears in Natural Law, which was originally printed in Benjamin Tucker’s anarchist periodical Liberty and later reprinted as a separate pamphlet of 20 pages. In this and in other later treatments we find a somewhat more radical treatment of natural law that Spooner presented in The Unconstitutionality of Slavery, but these exhibit a different emphasis rather than a shift in doctrine. Throughout his various discussions, Spooner argued that natural law and its concrete expression in terms of natural rights (which receive an important treatment in A Letter to Thomas F. Bayard, 1882), are the only legitimate basis for political obligation. Human legislation has value only insofar as it specifies objective procedures for the enforcement of natural rights. Legislators are incapable of changing the natural law in any fashion, so to the extent that they pass laws that violate natural rights, those laws have no moral authority whatsoever. As Spooner put it in Natural Law (p. 20):

What, then, is legislation? It is an assumption by one man, or body of men, of absolute, irresponsible, dominion over all other men whom they can subject to their power. It is the assumption by one man, or body of men, to subject all other men to their will and service. It is the assumption by one man, or body of men, of a right to abolish outright all the natural rights, all the natural liberty of other men; to make all other men their slaves; to arbitrarily dictate to all other men what they may, and may not, do; what they may, and may not, have; what they may, and may not, be. It is, in short, the assumption of a right to banish the principle of human rights, the principle of justice itself, from off the earth, and set up their own personal will, pleasure, and interest in its place. All this, and nothing less, is involved in the very idea that there can be any such thing as human legislation that is obligatory upon those upon whom it is imposed.

In Areopagitica (1644), John Milton summarized the basic purpose of political philosophy: “[H]ere the great art lies, to discern in what the law is to bid restraint and punishment, and in what things persuasion only is to work.” This perfectly describes the task undertaken by every major classical liberal and libertarian political philosopher. When is it morally proper to use physical force against others, and when should we restrict our attempts to persuade to purely voluntary methods? A major function of a theory of rights, for Spooner as for other classical liberals, is to draw a bright moral line between the spheres of coercive and voluntary interaction. We may have many moral obligations, or duties, towards others, but most of these are unenforceable in law; they depend instead on the voluntary compliance of the individuals involved. In Natural Law (p. 6), Spooner left no doubt that drawing this bright line was a major purpose in developing his theory of natural law and natural rights.

Man, no doubt, owes many other moral duties to his fellow men; such as to feed the hungry, clothe the naked, shelter the homeless, care for the sick, protect the defenceless, assist the weak, and enlighten the ignorant. But these are simply moral duties, of which each man must be his own judge, in each particular case, as to whether, and how and how far, he can, or will, perform them. But of his legal duty—that is, of his duty to live honestly towards his fellow men—his fellow men not only may judge, but, for their own protection, must judge. And, if need be, they may rightfully compel him to perform it. They may do this, acting singly, or in concert. They may do it on the instant, as the necessity arises, or deliberately and systematically, if they prefer to do so, and the exigency will admit it.

In subsequent essays I shall have more to say about Spooner’s doctrine of natural law and natural rights, especially how it applies to Spooner’s argument that slavery is unconstitutional.