Gandhi offers a fully developed metaphysics and epistemology–original even though it is grounded in classical Indian thought. For Martin Luther King, Protestant theology provides a core theory of human nature, but King navigates his way through debates in modern Protestantism and offers his own synthesis and draws political implications. Even for non-Hindus and non-Protestants, some premises that both of these authors share may be persuasive.
For Gandhi, there are truths–for example, about the good life and the just society–but they exceed any individual’s comprehension. Almost everyone (perhaps literally everyone) contributes valuable insights by observing the world from her own limited and fallible perspective.
The golden rule of conduct, therefore, is mutual toleration, seeing that we will never all think alike and we shall see Truth in fragment and from different angles of vision. Conscience is not the same thing for all. Whilst, therefore, it is a good guide for individual conduct, imposition of that conduct upon all will be an insufferable interference with everybody’s freedom of conscience.
Q. With regard to your Satyagraha doctrine, so far as I understand it, it involves the pursuit of Truth and in that pursuit you invite suffering on yourself and do not cause violence to anybody else.
A. Yes, sir.
Q. However honestly a man may strive in his search for Truth, his notions of Truth may be different from the notions of others. Who then is to determine the Truth?
A. The individual himself would determine that.
Q. Different individuals would have different views as to Truth. Would that not lead to confusion? …
A. That is why the non-violence part was a necessary corollary. Without that there would be confusion and worse.
According to Bhikhu Parek, Gandhi believes that “rational discussion and persuasion” are the “best way to resolve conflict.” However, these methods depend on well-motivated reasoners who are able to overcome our species’ deep cognitive and ethical limitations. Under ordinary circumstances, reasoning is likely to fail, because we are mired in our own interests and not rational enough to be persuaded by arguments. Violence is therefore tempting but intrinsically problematic. The violent actor assumes that she is right, even though we are all inevitably wrong. Violence also threatens to erase the insights of the target by silencing or even eliminating her, or it may force her to do something without being sincere. On the other hand, voluntary sacrifice can touch the other person’s heart without negating her freedom.
Gandhi also believes that we ought to perform actions that are intrinsically meritorious without being concerned about their outcomes, which lie beyond our control. As Krishna teaches in the Baghavad Gita, “Motive should never be in the fruits of action.” Actions must be sincere in order to have value, and sincerity requires commitment by the heart and mind together. Unlike a typical action that is taken to achieve an end beyond the direct control of the actor, sacrifice remains connected to the person who sacrifices. For example, if I choose not to eat, that remains my will until the end of my fast. If my refusal to eat causes you to change your behavior, that may be good (assuming that my cause was right), but I am responsible only for forgoing the food, not for your behavior. I thus escape the pitfall of attaching my happiness and meaning to an end beyond my control.
Like Gandhi, King holds that violence “is immoral because it seeks to humiliate the opponent rather than win his understanding; it seeks to annihilate rather than convert. … It leaves society in monologue rather than dialogue.” Nonviolence is “the ultimate form of persuasion,” where the word “ultimate” means both the most powerful form and the one to try last, after arguments have failed. King also shares with Gandhi a theory of the human soul as both rational and affective, a recognition of the limitations of human understanding, and the ideal of a transcendent truth that we can only approach together. He says that he found in Hegel the idea that “truth is the whole,” which is roughly analogous to Gandhi’s remarks about Brahman, the universal soul.
However, King’s framework is Protestant rather than classically Indian, so his metaphysics is somewhat different. Human beings are made in God’s image and are granted freedom, but we are also fallen. God is personal, an actual character who loves us and can work with us. King says that personalism “is my basic philosophy,” the foundation of his faith in an active personal God and “the metaphysical basis for the dignity and worth of all human personality.” People have dignity and worth not because they are good but because of divine grace. King says that he agrees with Reinhold Niebuhr about “the reality of sin on every level of man’s existence,” contrary to a “great segment of Protestant liberalism” that is too optimistic about human nature. “While I still believed in man’s potential for good, Niebuhr made me realize his potential for evil as well.” King ultimately came to believe that Niebuhr had “overemphasized the corruption of human nature” because he had “overlooked” the power of divine grace to work with communities of people; yet King retained a sharp awareness of sin and evil.
Agape–disinterested love–is the answer for King. It serves to explain the nature and will of God, our relationship to God, and our obligation to other people. It is not “sentimental” and it does not ignore sin. Instead, King defines nonviolent resistance as “a very stern love that would organize itself into collective action to right a wrong by taking on suffering.” The combination of organization and collective action, love, and nonviolent sacrifice is essential.
These philosophical and theological positions cannot both be completely right, because they conflict at points. For instance, King’s God is personal whereas Gandhi’s divine is abstract. Gandhi acknowledges that God is love but attributes that view to Christianity and endorses it in the context of saying that “the human mind is a limited thing and you have to labour under limitations when you think of a being or entity who is beyond the power of man to grasp.” Christians contribute the partial insight that God is love; for Gandhi himself, God is Truth.
Nevertheless, the overlapping premises of these two philosophies seem plausible even in secular contexts and are compatible with behavioral science. People really are cognitively and ethically limited when we think and act alone, but we are capable of reasoning better when we come together in groups that are organized to bring out the best in us. We really do make better decisions when we preserve alternative views instead of violently suppressing them. Yet we cannot expect the best conclusions to emerge from deliberation alone; change aso requires organized sacrifice.
 That is Parek’s reading. Gandhi: A Very Short Introduction (Oxford University Press, 2001), p. 54.
 These quotations come from several articles in the newspaper Young India, but they were combined by Nirmal Kumar Bose in his Selections from Gandhi (Ahmedabad: Navajivan Publishing House, 1948), pp, 66-67, which carries a very strong endorsement from Gandhi. Thus I treat them as a coherent argument that Gandhi approved.
 Parek, p. 51
 King, Stride Toward Freedom, Kindle locations 2850 and 2892.
 King, location 1355; cf. Nicholas F. Gier, The Virtue of Nonviolence: From Gautama to Gandhi (Albany: SUNY Press, 2004), pp. 40-1
 King, Stride Toward Freedom, 1355, 1327
 King, “My Trip to the Land of Gandhi,” originally published in Ebony magazine,1959, in Martin Luther King Jr., I Have a Dream: Writing and Speeches that Changed the World, edited by James M. Washington, (Glenview, IL, Harper Collins, 1992), p. 44.
 Bose, 4.
 Christopher Beem relates Niebuhr’s theological commitment to human limitations to the findings of modern psychology and draws political implications in Democratic Humility: Reinhold Niebuhr, Neuroscience, and America’s Political Crisis (Lanham, MD: Lexington Books, 2015).
See also the relationship between justice and peace; the central role of sacrifice in social movements; how the Montgomery Bus Boycott used and created social capital; prophesy as a form of political rhetoric; and the need to consider evil in politics.