Was Martin Luther King, Jr. Right About the Arc of the Moral Universe?

Was Martin Luther King, Jr. Right About the Arc of the Moral Universe?

Today my book, The Moral Arc: How Science and Reason Lead Humanity Toward Truth, Justice, and Freedom, is published by Henry Holt. It took me four years to research and write. It is my most ambitious book to date. It is longer than my previous books because I cover a lot more ground, but more importantly I think that the topics I discuss are more substantive than those in my prior work. If you are of a mind to get a copy, doing so in the next few days or weeks is vital to the life of a book in terms of which titles make the bestseller lists (thereby giving them an added boost). As I am attempting to make the case for a secular, non-religious moral system grounded in science and reason, I hope this book in some small way helps support our movement to reduce dogmatism and irrationality in the world, and to increase the survival and flourishing of sentient beings everywhere. I hope you agree. The following essay is based on the book’s Prologue. Thank you for reading it.

On Sunday, March 21st, 1965, about 8,000 people gathered at Brown Chapel in Selma, Alabama and began a march to the capitol building in Montgomery. At the front of the crowd was the Reverend Dr. Martin Luther King Jr., and they were marching for one reason. Justice. They wanted simply to be given the right to vote.

They had tried to march twice before, but were met with tear gas, billy clubs, and rubber tubing wrapped in barbed wire. And both times they were forced to turn back. But not this time. This time President Lyndon B. Johnson ordered 2,000 National Guard troops to protect the marchers. And so for five days, over a span of 53 miles, through biting cold and frequent rain, they marched. Word spread, the number of demonstrators grew, and by the time they reached the capitol building on March 25, their numbers had swelled to at least 25,000.

From the back of a flatbed truck parked in front of the steps to the state capitol Dr. King delivered his stirring anthem to freedom. He asked, rhetorically, “How long will prejudice blind the visions of men, darken their understanding, and drive bright-eyed wisdom from her sacred throne?” And “How long will justice be crucified and truth bear it?” In response, Dr. King offered words of counsel, comfort, and assurance, saying that no matter the obstacles it wouldn’t be long before freedom was realized because, he said, “truth crushed to earth will rise again,” “no lie can live forever,” and “the arc of the moral universe is long, but it bends toward justice.”

It was one of the greatest speeches in the history of public oratory. And it worked. Less than five months later, on August 6th, 1965, President Johnson signed the voting rights act into law. It was just as Dr. King had said—the arc of the moral universe is long but it bends toward justice.

Does it still bend in the right direction? It’s hard to watch the news and not think otherwise, but as President Bill Clinton cautioned in a recent speech, we should follow the trend lines, not the headlines.

When we do so we can see improvements in the domain of morality evident in many areas of life. Governance: the rise of liberal democracies and the decline of theocracies and autocracies. Economics: broader property rights and the freedom to trade goods and services with others without oppressive restrictions. Rights: to life, liberty, property, marriage, reproduction, voting, speech, worship, assembly, protest, autonomy, and the pursuit of happiness. Prosperity: the explosion of wealth and increasing affluence for more people and the decline of poverty worldwide. War: a smaller percentage of people die as a result of violent conflict today than at any time since our species began. Slavery: outlawed everywhere in the world. Homicide: rates have fallen precipitously from over 100 murders per 100,000 people in the Middle Ages to less than 1 per 100,000 today in the Industrial West. Judicial restraint: torture and the death penalty have been almost universally outlawed by states. Judicial equality: citizens are treated more equally under the law than any time in the past. And civility: people are kinder, more civilized, and less violent to one another than ever before.

What is the cause of this moral progress? Most people associate it with religion, but in fact I believe that most of the moral development of the past several centuries has been the result of societies moving toward more secular forms of governance and politics, law and jurisprudence, moral reasoning and ethical analysis. Over time it has become less acceptable to argue that my beliefs, morals, and ways of life are better than yours simply because they are mine, or because they are traditional, or because my religion is better than your religion, or because my God is the One True God and yours is not.

It is no longer acceptable to simply assert your moral beliefs; you have to provide reasons for them, and those reasons had better be grounded in rational arguments and empirical evidence or else they will likely be ignored or rejected.

Historically, we can look back and see that we have been steadily—albeit at times haltingly—expanding the moral sphere to include more members of our species as legitimate participants in the moral community. The burgeoning conscience of humanity has grown to the point where we no longer consider the wellbeing only of our family, extended family, and local community; rather, our consideration now extends to people quite unlike ourselves, with whom we gladly trade goods and ideas and exchange sentiments and genes, rather than beating, enslaving, raping, or killing them.

Gay rights and same-sex marriage is a prime example. A decade ago almost everyone was against it. A decade from now virtually everyone will be for it. And we will look back at our current debates like we now reflect on the inanity of arguments from decades ago in favor of black-and-white drinking fountains and against interracial marriage.

We have many social and moral problems left to solve, to be sure, and the direction of the arc will hopefully continue upwards long after our epoch so we are by no means at the apex, but there is much evidence to support the fact that Dr. King was right—the arc of the moral universe really does bend toward justice.

About the Author:

Dr. Michael Shermer is the Publisher of Skeptic magazine, a monthly columnist for Scientific American, a Presidential Fellow at Chapman University, and the author of The Moral Arc. His previous books include: The Believing Brain, Why People Believe Weird Things, Why Darwin Matters, The Mind of the Market, How We Believe, and The Science of Good and Evil.


  1. Burton Brunsoon January 21, 2015 at 10:59 am - Reply

    Generally, I agree with you. But specifically, there are several points that are a bit pollyannish. Theocracy is thrinving in much of the Muslim world. As is slavery also. In the matter of free speech, there are dozens of people in jail today in Europe for having said or published views of the Holocaust that were not inherently offensive but contradicted a compulsory established view. Curiously, those laws involve protecting Semites (all Semites, not just Jews) from abusive comment. Muslims are Semites. Yet, they (and others) were subject to considerable insult without response from law enforcement. Torture is illegal. Yet, like the law protecting Semites from insult, it is selectively enforced.
    Please bear with a short vignette. Charlie is a ten-year-old who reacts very poorly to peanuts. Not a choice on his part. His body just won’t cooperate with eating peanuts. All his playmates eat peanut butter sandwiches. He feels left out. He puts a label “Peanut Butter” on a jar of strawberry jam. Now he can eat a “Peanut Butter” sandwich, with the rest of the kids. But, should the government require that all strawberry jam should henceforth be labelled Peanut Butter? Should the federal government invalidate existing state laws requiring that food be accurately labelled? For hundreds of years, hundreds of millions of people have considered marriage to be a partnership between a man and a woman. There is no law against two (or more) men or women forming a partnership with all the attributes of marriage.. They are free to do so under existing laws. Are they also free to require that the hundreds of millions must change their definition of the word? Charlie can have jam on his alleged peanut butter sandwich, but should the rest of the world be required by law to share his fantasy?

    • Gabriel January 21, 2015 at 3:22 pm - Reply

      Burton, you provide a good example of how people are stuck in the past. What people believe does not always make it right, for example millions of people believe in a soul, however there is no evidence to support that belief.
      A more relevant vignette for the moral arc might be something like this.
      Charlie is new to a school where the kids have been taught that the only kind of “real” sandwich is a peanut-butter sandwich. When they find out that Charlie is eating a jelly sandwich they either don’t want him to have the right to eat that sandwich at school or at the very least not be able to call it a sandwich. So instead of worrying about renaming and outlawing certain kinds of foods , it might be best to teach the ignorant existing students that there are in fact other types of sandwiches. And they can be just as nutritional or even better than jelly sandwiches. And most of all it has no affect on the sandwiches that they previously thought were the only kind.

    • Max February 8, 2015 at 12:49 am - Reply

      What law protects Semites from insult? There’s a law that prohibits denying genocide, including the Holocaust and the Armenian genocide.
      And the law prohibiting genocide denial should prohibit drawing cartoons of Mohammed? If anything, it should prohibit denial of genocides carried out BY Mohammed and his followers.
      Oh, and Muslims are Semites? Especially the Indonesian ones, right?
      SMH. “Better to remain silent and be thought a fool than to speak out and remove all doubt.”

  2. Sid Plait January 21, 2015 at 3:45 pm - Reply

    Excellent words, Gabriel, and an excellent thought as an example.

    So, Burton, the answer is, “yes”. The laws should be changed. Part of a “free” society is the allowance of everyone to believe and do what they want, without restriction, as long as they don’t harm anyone else with what they believe or do.

    Explain to me how a gay or lesbian couple hurt or damage me or society in any way (except the outrageous assertions by far-right or far-left religious leaders – you can keep those if you consider any of them true).

    Restricting gays and lesbians from marrying legally is discrimination. Marriage between a man and a woman is actually a kind of arbitrary concept. Just because most people do it doesn’t mean there aren’t other possibilities.

    Keeping that restriction would be like setting a law in the U.S. that Christianity is the only allowable religion because most people in this country are Christians. In a free society, that wouldn’t even be a concept.

    Why should LGs be restricted?

    By changing the definition of marriage, we become a little less intolerant.

    • Sid Plait January 21, 2015 at 3:46 pm - Reply

      Actually, I meant to say in my first paragraph to Burton that laws and definitions should change, eventually across the globe.

  3. Joseph J. Clay January 21, 2015 at 8:08 pm - Reply

    Martin Luther King was a Mason, and he is an example for all the people who fight for the Human Rights

  4. retired urologist January 22, 2015 at 6:52 am - Reply

    “It is no longer acceptable to simply assert your moral beliefs; you have to provide reasons for them, and those reasons had better be grounded in rational arguments and empirical evidence or else they will likely be ignored or rejected.”

    I wish this were true. Perhaps you are surrounded primarily by intellectuals and academics.

  5. Stephen January 22, 2015 at 1:46 pm - Reply

    @retired. In most of my graduate-level classes moral reasoning is based on feelings. Professors often encourage students to develop feelings-based arguments in class debates. I even had one student want to hit me because I scoffed when he said “all data is made up by rich white men and therefore meaningless”. Serious. I wonder if it’s just my institution or academia in general.

  6. Burton Brunson January 22, 2015 at 3:50 pm - Reply

    I’m a fair athlete, not a great one, or even a really good one. But, maybe I could make it in the NFL, if I were 7 feet tall. I have a legal and moral right to be seven feet tall. By current standards, I’m 72 inches tall. If we redefine a foot as being 10 inches long, I;d be 7’2″ — maybe I could make it in the NFL. Suppose I were in a position of great power, where I could redefine a foot as 10 inches. Think what that would do to engineering, architecture, almost everything. Would I be wrong in issuing such a decree? But I have a right to be seven feet tall.
    A skeptic might note “Sit down, Burt, you’re barely six feet.” I’m barely six feet because the world lives in the past, defining a foot in obsolete terms. I have a right to be seven feet. The world should be changed to suit me.
    To some people, including me, this comment is not nearly as silly as the proposition that hundreds of millions of people must revise their vocabularies to suit a relatively small group that has easy other options to achieve their reasonable goals.

  7. Bad Boy Scientist January 22, 2015 at 4:59 pm - Reply

    Speaking as a scientist who uses empirical evidence to study physical phenomena, I am skeptical – Dr Schermer’s seems to link morality with freedom, justice & truth. All four of those terms are intangibles and very hard to pin down (ask a Philosopher) so how in the world do we find empirical evidence regarding any of them? I cannot tell if he speaks wisdom or non-sense.

    Take one of those intangibles: freedom. When one asserts to me, “We have more freedoms today than we did 100 years ago.” I reply “How do you measure that? Is there some sort of ‘Freedometer’ that objectively measures freedom or is this another case of ‘I know it when I see it’? ”

    Certainly some Americans have more freedom but all have lost some freedom over the same interval of time. Today we have universal suffrage and the Civil Rights Act but we also have the War of Drugs (and the erosion of the Bill of Rights it brought with it). How can we show, empirically, that our aggregate freedom is greater today than it was back then?

    It is fine for Reverends to talk of Freedom, Justice and Moral Arcs – that is their domain – but we empiricists need to invent Freedometers, Justice-scopes, and Moral detectors before we can speak seriously on the topic.

  8. Gabriel January 23, 2015 at 12:11 pm - Reply


    Try again, your argument is looking especially weak after that confusing vignette that is nothing more than a perfect example of a false equivalency. Be honest about why you are upset. Is it really because of the evolution of the meaning of the word? Are you some sort of advocate for perpetual finite definitions? Would you describe your marriage as being gay? Or do you go against the millions of people who used to use the word to describe “happy” and instead use it in its modern context? Time to stop playing games and just say what you mean.

  9. Burton Brunson January 25, 2015 at 6:37 pm - Reply

    Why do you think I’m upset? My comment contained a touch of humor (something alien to a certain type of mentality) but there was no false equivalency. Both covered an important and long-established social practice (the nature of marriage, and the basis for measuring), and the situations under which those practices might change. I don’t recall advocating perpetual finite definitions, but admit that I think there are some words that should be effectively permanent — such as mathematical terms. (Should mathematically challenged people be supported in saying pi is exactly 3, because they have a right to compute areas, too?)
    Evolution involves changes that are, from our point of view, random. The first fishes came on land not because a fish council decided they had the right to do so, but because they did it. The first humanoids to stand erect did it because their ability and desire to do so just happened, not because a chorus of Alley Oops agitated for the act. To change the words gay and marriage by use of media overkill and even federal law — that can happen, but it’s the opposite of evolution. Coercion would be a better term.
    The word marriage is an abstraction. An abstraction doesn’t have moods. But the partners in my marriage are very gay. What about the millions of people who still use the word marriage to describe a partnership of a man and woman? Do you “go against” them? Why?
    It’s a matter of simple logic. Two men (or women) have no “right” to be in a partnership that by definition involves one man and one woman. People who think with their feelings might disagree, but it’s a matter of logic. If two men or women are involved, then it doesn’t meet the requirement of the definition. To have same-sex marriages, it’s absolutely necessary to change the definition of the word marriage. I could get along with the word evolving to include same-sex. But I don’t passively accept the change being compelled by federal courts acting as agents of those who manipulate the herd that maintains that logic is anything that makes someone feel warm and fuzzy.

  10. Gabriel January 28, 2015 at 2:25 pm - Reply

    You admittingly compare something abstract to mathematics. which is a false equivalency. You do better without the poor analogies. There is no need to apply your false logic. Marriage is a verb and a noun. Same sex couples are aloud to marry(verb) in the majority of the United States after which they are in a legal marriage(noun). If this takes away from your warm and fuzziness, you are probably not alone. But like mathematics, the answer is not worried about the way it makes you feel.

  11. Max February 8, 2015 at 1:00 am - Reply

    So the “Arab Spring” led to the rise of ISIS, ongoing chaos in Libya, and Shiite rebels taking over Yemen. The Muslim Brotherhood took over Egypt for a year until a backlash reinstated military rule. Russia annexed Crimea and brought war back to Europe, and Communist China effectively took over Senkaku islands from Japan and is now a bigger economy than the U.S.

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