By Tyler Lynch

The actions of Martin Luther King, Jr. in his campaign against segregation had as their wellspring a Judeo-Christian tradition of nonviolence and justice that stretches from the Old Testament through to Christian philosophers of the medieval period. In particular, the natural law philosophy of St. Thomas Aquinas that provides a major framework for King’s ethical thought, and his justification of the Civil Rights Movement. This essay examines the thought of Dr. Martin Luther King, especially in his Letter From Birmingham Jail, in comparison to and contrast with the thought of Thomas Aquinas, with focus on his Treatise on Law. Tracing this lineage is crucially important to understanding King’s views on human rights and justice. Indeed, without considering King’s spiritual heritage it is difficult, if not impossible, to understand the moral framework of the Civil Rights Movement at all.

            Perhaps the most accessible introduction to the ethical convictions of King lie in his Letter From Birmingham Jail, drafted in 1963 while King was confined in the eponymous Alabama jail. Written as a response to a letter published by eight white clergymen      who denounced King’s work as “unwise and untimely,” King delivered, under trying circumstances, a work of exceptional lucidity and moral force (King). The letter is a justification not only of the foundations and principles of the American Civil Rights Movement, but a timeless articulation of the struggle of all oppressed people and a vindication of the “yearning for freedom” (King).

In response to the charge that he and his cohorts showed a “willingness to break laws,” King marshalled the philosophy of classic Christian thinkers like Augustine and Aquinas in rebuttal (King). King concedes that it is an apparent paradox and a “legitimate concern” that the civil rights movement advocates adhering to some laws and breaking others. However, he responds that “there are two types of laws: just and unjust.” With this quotation, King has already formulated his argument in the terms of Thomas Aquinas before Aquinas is even mentioned in the next sentence. Aquinas agrees as to the the inherent just or unjust nature of “laws framed by man” in the Treatise on Law, Q.96, Art.4, c.o.. King proceeds to make another fundamentally Thomistic argument: that it is morally and legally right to obey just laws, while “one has a moral responsibility to disobey unjust laws.” Aquinas is again in concordance, arguing that unjust laws are “not binding in conscience” (ST I-II, Q.96, Art.4, c.o.). King has extended this logically from the realm of conscience into the practical sphere.

The pressing question, for both Aquinas and King, is how to differentiate between a just law and an unjust one. King proceeds to answer this question “in the terms of St. Thomas Aquinas,” although he was already using Thomistic language. Thus it is to a closer examination of those terms that we should turn to next.

            Aquinas distinguishes between four types of law in his Treatise on Law, written in the 13th Century as part of his magnum opusof theology and philosophy, the Summa Theologica. The four types are eternal law, natural law, human law, and divine law. Eternal law is the rational ordering principle of the natural universe, ultimately emanating from God. It is the “Supreme reason” that “implies order” into created things through rational principles (ST I-II, Q.1, Art.1; a.d.3).  The eternal law “must be called eternal” because its source, God, “is not subject to time”, and it is a law because it predictably governs all of existence (ST I-II, Q.1, Art.1, c.o.). Indeed, Aquinas would argue that the universe itself is only rational because it is superintended by the rational principles of the eternal law, which draws all things to their “proper act and end” (ST I-II, Q.91, Art.2, c.o.).

            Natural law is an extension of the eternal law, encompassing those elements of it that govern the actions of free, rational beings. For Aquinas, “the natural law is nothing else than the rational creature’s participation in the eternal law” (ST I-II, Q.91, Art.2, a.d.1). The rational participation is important because, as Aquinas says,  participation in the eternal law is essentially to law in itself insofar as that participation is rational and intellectual in character (ST I-II, Q.91, Art.2, a.d.3). Aquinas quotes the New Testament to define natural law as something inherently knowable by all, which all human beings have consciousness of. It is the universal, objective standard by which we know “what is good and what is evil” (ST I-II, Q.91, Art.2, c.o.).

            Human law is rooted in natural law, but extends it to the temporal and the specific. Natural law may be interwoven with the fabric of our being, inclining us to what is good, but it does not specifically dictate proper action in every frame of human action. Thus, human law is necessary to establish the “general rules and measures of all things relating to human conduct” (ST I-II, Q.91, Art.3, a.d.2). It concerns the “particular determination of certain matters” and as such, does not have the universal quality of eternal or natural law (ST I-II, Q.91, Art.3, c.o.). Aquinas fully accepts that human law would result in “different and contrary laws” across time and culture to facilitate different modes of being in the world (ST I-II, Q.91, Art.4, c.o.). It is human law that is referred to when Aquinas and King state that laws can be just or unjust.

            Divine law is not directly referenced in the Letter from Birmingham Jail, but should not be ignored in a discussion of Thomistic natural law philosophy. Divine law is that which concerns the human soul beyond its rational elements, and is not solely discernible by natural reason. “Man is ordained to an end of eternal happiness,” says Aquinas, “which is inproportionate to his natural faculty” (ST I-II, Q.93, Art.4, c.o.). It is divine law that concerns this end. Where reason falls short, where the “uncertainty of human judgement” confuses, where “man is not competent to judge,” the transcendent Divine law steps in, pulling man to his predestined end of eternal happiness and working to “forbid all evil deeds” and ensure that objective good is rewarded (ST I-II, Q.93, Art.4, c.o.). While there is a clear continuum from eternal law, which orders the universe, to natural law, which governs good and evil out of the eternal law, to human law, which extends natural into specific situations, divine law is in a class of its own. It is not entirely rationally explicable, as it “is given by God […] in a yet higher way” (ST I-II, Q.93, Art.4, c.o.; a.d.2). Its purpose is also not the simple avoidance of evil and the pursuit of good, but salvation and eternal union with God. With this framework in place, it is possible to understand the argument made by Aquinas and King as to what constitutes an unjust law.

            King defines an unjust law using Aquinas’s formulation as “a human law that is not rooted in eternal law and natural law,” but this is rather vague. It is rather simple for a law to be rooted in natural law, as long as it fits with the central precept of that law: “that good is to be done and pursued, and evil is to be avoided” (ST I-II, Q.94, Art.2, c.o.). This first precept is very broad, and does not detail which things are good and which are evil. Martin Luther King then makes four arguments in an attempt to show that segregation laws do not bring about good or avoid evil, and are thus not based in natural law, making them unjust on Thomistic terms.

King’s first argument is not especially Thomistic. King’s argument is that “any law that degrades human personality is unjust” (King). This claim is never made by Aquinas in the Treatise on Law, and is more ideologically concordant with the theology of Martin Buber and Paul Tillich, quoted by King to show that segregation “distorts the soul and damages the personality” (King). However, this argument is not wholly alien to the language of the Treatise. Aquinas speaks of “the last end of human life” as “bliss or happiness,” and writes that the natural law aids in “preserving human life, and of warding off its obstacles” (ST I-II, Q.90, Art.2, c.o.; Q.94, Art.2, c.o.). Segregation law clearly inhibits the pursuit of happiness and has no effect in preserving life or alleviating its difficulties. It is not hard to see on Thomistic terms that through degrading the human condition, segregation law degrades the personality as well, which is Divinely-directed towards happiness. While this argument is not explicitly Thomistic, it is roughly compatible with his philosophy.

King is in more Thomistic territory when he writes that “an unjust law is a code that a numerical or power majority group compels a minority group to obey but does not make binding on itself” (King). This is deeply unjust for Aquinas, who rallies a host of quotes in opposition to the attitude. “Whatever law a man makes for another, he should keep himself,” he writes (ST I-II, Q.96, Art.5, a.d.3). Aquinas quotes Jesus in condemnation of those that “bind heavy burdens and lay them on men’s shoulders, but with a finger of their own they will not move them,” a phrase all the more pertinent when seen in context of the emancipation of African-Americans from slavery and segregation (ST I-II, Q.96, Art.5, a.d.3). Here King and Aquinas are in direct agreement.

King next argues against illegitimately-made laws, taking his argument from Aquinas. King writes that “a law is unjust if it is inflicted on a minority that, as a result of being denied the right to vote, had no part in enacting or devising the law” (King). Aquinas rejects any law not made by and for the people, saying that “the making of a law belongs either to the whole people or to a public personage who has care of the whole people” (ST I-II, Q.90, Art.3, c.o.). There is no room for infliction of laws on minorities at all. “Coercive power is vested in the whole people or in some public personage,” Aquinas repeats (ST I-II, Q.90, Art.3, a.d.3).

Finally, King argues that a law can be “just on its face and unjust in its application” (King). King references his charge of “parading without a permit” as an example of a reasonable law being used oppressively. Aquinas is sensitive to the same problem, and is utterly opposed to the interpretation of law contrary to the common good. “If a case arise wherein the observance of that law would be harmful to the common good,” he writes, “it should not be observed” (ST I-II, Q.96, Art.6, c.o.). Aquinas cites the example of a city whose gates are barred by law, and the injustice of maintaining that law if it would mean the deaths of citizens outside the walls (ST I-II, Q.96, Art.6, c.o.). Aquinas and King are in essential agreement as to what constitutes an unjust law under natural law philosophy.

            However, the two thinkers differ significantly on the value of civil disobedience, with Aquinas being far less eager to advocate social disturbance. He values order and forbearance to a degree that King would, most likely, find deeply disappointing. While Aquinas concedes that unjust laws must not be followed, he qualifies this by giving possible exception “in order to avoid scandal or disturbance” (ST I-II, Q.96, Art.4, c.o.). A man is not bound to obey a law that “inflict unjust hurt on its subjects,” but only provided “he avoid giving scandal or inflicting a more grievous hurt.” Absent in the Treatise on Law is any sense of the need to “arouse the conscience of the community,” something King states is borne from “highest respect for the law” (King).

           King was emphatically opposed to acting out of fear of scandal, something Aquinas takes quite seriously. Aquinas sounds a good deal like the “white moderate” whom King rebuked as the “great stumbling block in [the Negro’s] stride toward freedom.” The white moderate, says King, “is more devoted to ‘order’ than to justice; [and] prefers a negative peace which is the absence of tension to a positive peace which is the presence of justice.” Whereas it is imprudent to place Aquinas squarely on the side of order rather than justice, social stability is far more dear to Aquinas’s heart than King’s. King would never be resigned to tolerance of an unjust status quo by any means— he believed the erasure of unjust laws “must be demanded by the oppressed” and would occur no other way (King). He saw no other choice for African-Americans but to “openly, lovingly” disobey the segregation laws that oppress them and willingly accept the consequences (King). Aquinas’s concern for social order is not to be found in the Letter from Birmingham Jail.

           This difference comes down, in large part, to Aquinas’s conviction of the inherent divine sanction of power and order—a conviction Martin Luther King seems to lack. Aquinas believed there was something unsettling and potentially anarchical in disobeying laws—even unjust ones  —laid down by authority, because authority is Divinely sanctioned. Aquinas quotes the Letter to the Romans to justify this, stating that “all human power is from God,” and anyone that “resisteth the power. . . resisteth the ordinance of God” (ST I-II, Q.96, Art.4, a.d.1, quoting Rm 13:1.2). King, however, is adamant in his Letter that “law and order exist for the purpose of establishing justice.” One wonders whether, for Aquinas, law and order are something closer to goods in themselves.

For all this, the positions of Thomas Aquinas and M.L.K. are not so very disparate. Despite his concern with order and avoidance of scandal, Aquinas never denies that unjust laws are not laws binding in conscience, and in this regard stands fundamentally with King. King himself shows a certain respect for civil order too, stating that he is not an anarchist and does not “advocate evading or defying the law” (King). “One who breaks an unjust law must do so openly, lovingly, and with a willingness to accept the penalty,” he wrote. King’s willingness to accept the penalties of breaking unjust laws (in his case, imprisonment for protesting without a permit) elevates him about the mere disturbers of the peace that Aquinas is so fearful of.

The looming presence of St. Thomas Aquinas in the Letter from Birmingham Jail would not have been lost on the eight churchmen to whom King wrote. For the controversial Baptist preacher to utilize the philosophy of the perhaps most eminent theologian and philosopher in Western Christianity to buttress his campaign of civil disobedience was an effective rhetorical technique, and bolsters King’s credibility by basing his arguments in terms the clergymen would understand. Martin Luther King is highly effective in giving credence to his arguments through highly pertinent appeals to authority, from the Biblical in St. Paul, the modern in Paul Tillich, to the secular in Thomas Jefferson. The influence of Thomas Aquinas on M.L.K. is no mere rhetorical device. Indeed, it is difficult to fathom King’s justification of direct action and civil disobedience having the same weight and philosophical rigour, were it not for his deep and abiding understanding of the natural law theory of Thomas Aquinas. We find the Treatise on Law has gained an unexpected legacy. Despite being no progressivist himself, Aquinas lay down in the Treatise on Law an enduring and robust defense of justice that would become one of the moral cornerstones of the Civil Rights Movement in America.

Works Cited

Aquinas, St. Thomas. “Treatise on Law.” Sophia Project. Accessed 17 Nov, 2018

King, Jr., Martin Luther. “Letter from a Birmingham Jail.” University of Pennsylvania. Accessed 17 Nov, 2018

“Statement and Response: King in Birmingham.” Trinity International University. Accessed 16 Nov, 2018