“The slavery question perplexes the president almost as much as ever, and yet I think he’s about to emerge from the obscurities where he’s been groping into somewhat clearer light.”—Salmon P. Chase, treasury secretary, 1862

As a matter of political strategy, Abraham Lincoln left slavery alone. An abolitionist at heart, he considered preserving the Union a higher priority than emancipation. The intellectual and emotional conflicts in Lincoln’s calculation, University of Chicago philosopher Jonathan Lear believes, “ate at his soul.”

In that internal struggle, Lincoln illuminates Lear’s notion of irony. As Lear defines the concept, it represents not just a gap between aspiration and action—and certainly not the detachment implied in its common modern definition—but an unsettling awakening to that disparity within ourselves. “The idea is that when irony is working,” he says, “it’s calling us in a kind of anxious way to live up to the ideals we already think we have.”

Lear explores that idea in A Case for Irony (Harvard University Press, 2011), tracing his understanding of the notion to Kierkegaard, who experienced it most acutely in a spiritual context. “He was a very religious Christian, and he could feel the religion sort of becoming flattened and deadened,” Lear says. “So for him the most important ironic question was, ‘Among all Christians, is there a single Christian?’”

Many practicing Christians might have answered with a reflexive yes, but for Kierkegaard there were few, if any—himself included. “A lot of times it looks as though he’s making fun of Christians, or Christendom, people who think they’re Christians,” Lear says, but really he was expressing an ironic awareness of his own failings and calling people to see those failings in themselves, using his writing as an act of Christian charity. “His authorship,” Lear adds, “is his best attempt to love his neighbors as himself.”

The true experience of irony, in Lear’s formulation, is “first-personal confrontation”—singular or plural, me or we—never external, distinguishing it from contemporary sarcastic finger pointing. The nature of Lincoln’s suffering during the Civil War reflected that true ironic experience, says Lear, who pored over the president’s letters and speeches. Grappling with the question of slavery as a social ill—perhaps the ultimate American irony in a country founded on freedom—and as a raging personal conflict, Lincoln becomes, for Lear, “a Kierkegaardian hero.”

He made preserving the Union a priority and compromised for it, personally and politically. “I think he might have made the wrong decision,” Lear says, “but what I do think is that he made a serious decision, and one that went into the heart of his suffering.”

Lincoln raised the idea of an emancipation proclamation with his cabinet in July 1862. He made it public in September, after a Union military triumph at Antietam gave him political cover, and it took effect on January 1, 1863. “I struggled nearly a year and a half to get along without touching the ‘institution,’” Lincoln wrote to Major General John McClernand, and even after he “conditionally determined to touch it,” the implementation plodded.

The lag between announcing the proclamation in September and its January 1 enactment gave states that had seceded the opportunity to return to the Union. If they had, their slaves would not have been emancipated (the president had the authority to suspend civil law only in states in rebellion; slaves in four Union border states were not freed under the proclamation). The Southern states did not return and, his order made, Lincoln added in his letter to McClernand, “it must stand.” His conscience—provoked, like his country, toward fulfilling its ideals—ultimately could not endure half slave and half free.