At a speech in Peoria, Lincoln explained that if the slave “is not a man, why in that case, he who is a man may, as a matter of self-government, do just as he pleases with him. But if the negro is a man, is it not to that extent, a total destruction of self-government?” In his debate with Stephen Douglas, Lincoln showed that Douglas’s claim to have no position on slavery — and that each locality should decide for itself — amounted to taking a stance on slavery: “When Judge Douglas says that whoever, or whatever community, wants slaves, they have a right to have them, he is perfectly logical if there is nothing wrong in the institution; but if you admit that it is wrong, he cannot logically say that anybody has a right to do wrong.”
This forced the question of the morality of slavery. To answer it — and show its relevancy to constitutional debates — both Adams and Lincoln appealed to the Declaration’s natural-law truths. Dyer notes that Adams appealed to a “transhistorical basis of right against which the historical practice of slavery was thought to be antithetical.” And this source of right “had a metaphysical basis in reality while also having a historical basis in America’s founding documents,” thus rendering it “relevant to constitutional adjudication.” If all men are really created equal and endowed by their Creator with rights, slavery was self-evidently wrong.
After the Supreme Court’s decision in Dred Scott, Lincoln affirmed judicial review but denied judicial supremacy. The Court’s ruling was binding for the parties in that case. Yet while it deserved “very high respect” in similar cases and from other branches of government, Lincoln said, the legislative and executive branches were co-equal with the Court and had a duty to uphold the Constitution as they understood it: To give the Court the final word on what the Constitution meant was to “resign their government into the hands of that eminent tribunal.” Lincoln further insisted, “If I were in Congress, and a vote should come up on a question whether slavery could be prohibited in a new territory, in spite of the Dred Scott decision, I would vote that it should.”
These arguments require a certain metaphysics of morals. As Dyer notes, Lincoln’s view was that the Constitution “was informed by moral principles, grounded in human nature, which provided the logical basis for republican government.” These principles were binding because of God’s design. Dyer argues that “in Locke’s natural-law theory, as interpreted by the Founders and amalgamated with American Protestant theology, a providential God provided the grounds of moral obligation to obey the laws of nature.” Contemporary American legal theorists reject much of this: Vanderbilt law professor Mark Brandon notes that “invoking a standard of human dignity is problematic, not least because of its metaphysical roots. Human dignity evokes natural law and natural rights, which are off limits in the new constitutionalism.” But this, Dyer argues, undercuts our entire moral and political order: “If an intelligent, creating and moralistic God has not imbued the natural order with discernible purposes, then it is senseless to talk about morally binding laws accessible to human reason.” Dyer quickly adds that one need not start with belief in God and then work toward morality. Instead, the intelligible order of nature, our “grasp of human goods,” and the “distinction we draw between right and wrong” are themselves “evidence for the existence of such a providential God.”
Dyer closes the book with an assessment of Frederick Douglass’s public arguments against slavery. Measuring them, along with Lincoln’s, by the standards of Rawlsian public reason, Dyer concludes that Rawls’s attempt to find an overlapping consensus based on current political culture rules out appeals from so-called “comprehensive doctrines” and their deeper metaphysical sources. But the arguments of the antislavery constitutional theorists “were notable precisely because they challenged, from foundational premises, important aspects of their own public political culture.” This serves as a fitting reminder that the natural-law tradition should help us challenge important aspects of our own political culture as well.
– Mr. Anderson is the editor of Public Discourse: Ethics, Law, and the Common Good, the online journal of the Witherspoon Institute of Princeton, N.J.