We often speak of the dignity owed to a person. And dignity is a word that regularly appears in political speeches. Charters are promulgated in its name, and appeals to it are made when people all over the world struggle to achieve their rights. But what exactly is dignity? When one person physically assaults another, we feel the wrong demands immediate condemnation and legal sanction. Whereas when one person humiliates or thoughtlessly makes use of another, we recognize the wrong and hope for a remedy, but the social response is less clear. The injury itself may be hard to quantify.

Given our concern with human dignity, it is odd that it has received comparatively little scrutiny. Here, George Kateb asks what human dignity is and why it matters for the claim to rights. He proposes that dignity is an “existential” value that pertains to the identity of a person as a human being. To injure or even to try to efface someone’s dignity is to treat that person as not human or less than human—as a thing or instrument or subhuman creature. Kateb does not limit the notion of dignity to individuals but extends it to the human species. The dignity of the human species rests on our uniqueness among all other species. In the book’s concluding section, he argues that despite the ravages we have inflicted on it, nature would be worse off without humanity. The supremely fitting task of humanity can be seen as a “stewardship” of nature. This secular defense of human dignity—the first book-length attempt of its kind—crowns the career of a distinguished political thinker.

One of the most influential philosophers of liberalism turns his attention to the complexity of Lincoln’s political thought. At the center of Lincoln’s career is an intense passion for equality, a passion that runs so deep in the speeches, messages, and letters that it has the force of religious conviction for Lincoln. George Kateb examines these writings to reveal that this passion explains Lincoln’s reverence for both the Constitution and the Union.

The abolition of slavery was not originally a tenet of Lincoln’s political religion. He affirmed almost to the end of his life that the preservation of the Union was more important than ending slavery. This attitude was consistent with his judgment that at the founding, the agreement to incorporate slaveholding into the Constitution, and thus secure a Constitution, was more vital to the cause of equality than struggling to keep slavery out of the new nation. In Kateb’s reading, Lincoln destroys the Constitution twice, by suspending it as a wartime measure and then by enacting the Thirteenth Amendment to abolish slavery. The first instance was an effort to save the Constitution; the second was an effort to transform it, by making it answer the Declaration’s promises of equality.

The man who emerges in Kateb’s account proves himself adequate to the most terrible political situation in American history. Lincoln’s political life, however, illustrates the unsettling truth that in democratic politics—perhaps in all politics—it is nearly impossible to do the right thing for the right reasons, honestly stated.