More than most years, 2018 will be a year filled with remembrances of Martin Luther King Jr. because in it falls the 50th anniversary of King’s assassination.

It will also be a year filled with remembrances of 1968 itself as the culminating year of the 1960s, a year in which the country seemed divided even to the breaking point.

In many such remembrances, those two facts will be conjoined, and amid our present climate of political division and radicalized opposition, there will be much admiring discussion of King and the radicalism of that era, along with much lamentation that King’s late-1960s vision of an America thoroughly revolutionized in its core values passed, at least for a time, from the scene with him.

Unfortunately, absent from this discussion will be any significant appreciation of King’s moderation—a virtue that he himself, in the more sober expressions of his thinking, regarded as indispensable to his and his movement’s success.

In fact, the single best representation of King’s mind during the most successful portion of his career, the famous “Letter from Birmingham Jail,” is in large measure a reflection on the virtue of moderation and a justification of King’s claim to it.

King felt compelled to justify his claim to moderation, because it was on precisely this ground that eight of his fellow clergymen had challenged him, in a public letter to King that appeared in Birmingham’s major newspaper.

These eight clergymen, all white, made their own claim to moderation. It was plausible enough, as they were all opponents of racial segregation and had written a public letter a few months earlier in which they called for Alabama Gov. George Wallace to abide by the Supreme Court’s anti-segregation rulings.

In their letter to King, they expressed a concern over his methods of street demonstration and civil disobedience, which they characterized as “extreme measures” likely to incite violence and sharpen divisions.

>>> Read Peter Myers’ essay, “The Limits and Dangers of Civil Disobedience: The Case of Martin Luther King Jr.

King began his response by noting that he seldom replied to critical letters due to the huge volume that he received. The letter from these eight clergymen was a special case, he wrote, because its authors were “men of good will”—men of faith, anti-segregationists, and moderates whose challenge to his own moderation he took very seriously.

In his response, King did not altogether reject the imputation of extremism.“Was not Jesus an extremist for love?” he asked, and were not the prophet Amos, and our own Presidents Thomas Jefferson and Abraham Lincoln, extremists for justice?

Nonetheless, he indicated that the charge stung him, and he defended his own extremism by explaining how it was consistent with and governed by the virtue of moderation, rightly understood.

In his book, “Stride Toward Freedom” (1958), King recalled how he had framed his task, as he prepared his initial speech to participants in the Montgomery bus boycott. “How could I make a speech that would be militant enough to keep my people aroused to positive action and yet moderate enough to keep this fervor within controllable and Christian bounds?”

Moderation can in some circumstances require militancy, but militancy can and must be moderate. The same idea informed King’s argument in the “Letter from Birmingham Jail.”

Within the eight clergymen’s frame of reference, the moderate position was to support gradual desegregation—in contrast to both Wallace’s extreme “segregation forever” position and the protesters’ demand for immediate desegregation.

Within King’s frame of reference, however, the moderate position was to conduct nonviolent, direct-action protests against segregation. This approach contrasted with what King called the “two opposing forces in the Negro community”: the extremes of demoralized complacency and of the “bitterness and hatred” propagated by those advocating violence and separatism.

King believed his own frame of reference was the proper one, because he held the gradual approach, judged in historical context, was in fact not a moderate position: “We have waited for more than 340 years for our constitutional and God-given rights.”

King’s commitment to moderation in the “letter” is actually broader and deeper than this rejection of gradualism. Two general points are of primary importance.

First, King’s militancy was moderate in that it incorporated a respect for tradition. He justified his activism by appealing to principles grounded in venerable Western and American traditions of natural law and natural rights philosophy.

Second, he defended his direct-action methods—including the practice of civil disobedience—as consistent with and even, in the proper circumstances, required by the rule of law. In King’s explanation, an appeal to higher-law principles of justice must not reflect a disdain for man-made law, but to the contrary, must preserve and exemplify “the highest respect for law.”

The “right to protest for right,” King maintained, is both a natural human right and a precious American inheritance. The spirit of righteous resistance is among the virtues of the American character—yet, like other such qualities, it loses its virtuous character when it is carried into extremism.

Those in our own day who feel themselves moved by this spirit would do well to learn this lesson from King’s “letter”: Resistance loses its righteousness when it ceases to be governed by the virtues of moderation and prudence.