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The Moral Arc: How Science Makes Us Better People

The Moral Arc: How Science Makes Us Better People

by Michael Shermer
The Moral Arc: How Science Makes Us Better People

The Moral Arc: How Science Makes Us Better People

by Michael Shermer



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Bestselling author Michael Shermer's exploration of science and morality that demonstrates how the scientific way of thinking has made people, and society as a whole, more moral

From Galileo and Newton to Thomas Hobbes and Martin Luther King, Jr., thinkers throughout history have consciously employed scientific techniques to better understand the non-physical world. The Age of Reason and the Enlightenment led theorists to apply scientific reasoning to the non-scientific disciplines of politics, economics, and moral philosophy. Instead of relying on the woodcuts of dissected bodies in old medical texts, physicians opened bodies themselves to see what was there; instead of divining truth through the authority of an ancient holy book or philosophical treatise, people began to explore the book of nature for themselves through travel and exploration; instead of the supernatural belief in the divine right of kings, people employed a natural belief in the right of democracy.
In The Moral Arc, Shermer will explain how abstract reasoning, rationality, empiricism, skepticism--scientific ways of thinking--have profoundly changed the way we perceive morality and, indeed, move us ever closer to a more just world.

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Product Details

ISBN-13: 9780805096934
Publisher: Holt, Henry & Company, Inc.
Publication date: 01/20/2015
Sold by: Macmillan
Format: eBook
Pages: 560
File size: 7 MB

About the Author

Michael Shermer
is the author of Why People Believe Weird Things, The Believing Brain, and eight other books on the evolution of human beliefs and behavior. He is the founding publisher of Skeptic magazine, the editor of, a monthly columnist for Scientific American, and an adjunct professor at Claremont Graduate University. He lives in Southern California.

Michael Shermer is the author of The Moral Arc, Why People Believe Weird Things, The Believing Brain, and several other books on the evolution of human beliefs and behavior. He is the founding publisher of Skeptic magazine, the editor of, a monthly columnist for Scientific American, and Presidential Fellow at Chapman University. He lives in Southern California.

Read an Excerpt

The Moral Arc

How Science and Reason Lead Humanity Toward Truth, Justice, and Freedom

By Michael Shermer

Henry Holt and Company

Copyright © 2015 Michael Shermer
All rights reserved.
ISBN: 978-0-8050-9693-4


Toward a Science of Morality

Science has nothing to be ashamed of even in the ruins of Nagasaki. The shame is theirs who appeal to other values than the human imaginative values which science has evolved. The shame is ours if we do not make science part of our world.... For this is the lesson of science, that the concept is more profound than its laws.

—Jacob Bronowski, Science and Human Values, 1956

The metaphor of the bending moral arc symbolizes what may be the most important and least appreciated trend in human history—moral progress—and its primary cause is one of the most understated sources: scientific rationalism.

By progress I accept the Oxford English Dictionary's historical usage as "advancement to a further or higher stage; growth; development, usually to a better state or condition; improvement." By moral I mean "manner, character, proper behavior" (as from the Latin moralitas), in terms of intentions and actions that are right or wrong with regard to another moral agent. Morality involves how we think and act toward other moral agents in terms of whether our thoughts and actions are right or wrong with regard to their survival and flourishing. By survival I mean the instinct to live, and by flourishing I mean having adequate sustenance, safety, shelter, bonding, and social relations for physical and mental health. Any organism subject to natural selection—which includes all organisms on this planet and most likely on any other planet as well—will by necessity have this drive to survive and flourish, for if they didn't they would not live long enough to reproduce and would therefore no longer be subject to natural selection.

Because I include animals (and, perhaps one day, extraterrestrial life-forms) in our sphere of moral consideration, by moral agent I mean sentient beings. By sentient I mean emotive, perceptive, sensitive, responsive, conscious, and therefore able to feel and to suffer. In addition to using criteria such as intelligence, language, tool use, reasoning power, and other cognitive skills, I am reaching deeper into our evolved brains toward more basic emotive capacities. Our moral consideration should be based not primarily on what sentient beings are thinking, but on what they are feeling. There is sound science behind this proposition. According to the Cambridge Declaration on Consciousness—a statement issued in 2012 by an international group of prominent cognitive neuroscientists, neuropharmacologists, neuroanatomists, and computational neuroscientists—there is a convergence of evidence to show the continuity between humans and nonhuman animals, and that sentience is the common characteristic across species.

The neural pathways of emotions, for example, are not confined to higher-level cortical structures in the brain, but are found in evolutionarily older subcortical regions. Artificially stimulating the same regions in human and nonhuman animals produces the same emotional reactions in both. Further, attentiveness, sleep, and decision making are found across the branches of the evolutionary tree of life, including mammals, birds, and even some invertebrates, such as octopodes. In assessing all the evidence for sentience, these scientists declared, "Convergent evidence indicates that non-human animals have the neuroanatomical, neurochemical, and neurophysiological substrates of conscious states along with the capacity to exhibit intentional behaviors. Consequently, the weight of evidence indicates that humans are not unique in possessing the neurological substrates that generate consciousness." Whether nonhuman animals are "conscious" depends on how one defines consciousness, but for my purposes the more narrowly restricted emotional capacity to feel and suffer is what brings many nonhuman animals into our moral sphere.

Given these reasons and this evidence, the survival and flourishing of sentient beings is my starting point, and the fundamental principle of this system of morality. It is a system based on science and reason, and is grounded in principles that are themselves based on nature's laws and on human nature—principles that can be tested in both the laboratory and in the real world. Thus I take moral progress to mean the improvement in the survival and flourishing of sentient beings.

Here I am specifically referring to individual beings. It is the individual who is the primary moral agent—not the group, tribe, race, gender, state, nation, empire, society, or any other collective—because it is the individual who survives and flourishes, or who suffers and dies. It is individual sentient beings who perceive, emote, respond, love, feel, and suffer—not populations, races, genders, groups, or nations. Historically, immoral abuses have been most rampant, and body counts have run the highest, when the individual is sacrificed for the good of the group. It happens when people are judged by the color of their skin—or by their X/Y chromosomes, or by whom they prefer to sleep with, or by what accent they speak with, or by which political or religious group they belong to, or by any other distinguishing trait our species has identified to differentiate among members—instead of by the content of their individual character. The Rights Revolutions of the past three centuries have focused almost entirely on the freedom and autonomy of individuals, not collectives—on the rights of persons, not groups. Individuals vote, not races or genders. Individuals want to be treated equally, not races. Rights protect individuals, not groups; in fact, most rights (such as those enumerated in the Bill of Rights of the US Constitution) protect individuals from being discriminated against as members of a group, such as by race, creed, color, gender, and—soon—sexual orientation and gender preference.

The singular and separate organism is to biology and society what the atom is to physics—a fundamental unit of nature. (Here I am not including social insects such as worker drone bees, whose members are genetically nearly identical.) Thus the first principle of the survival and flourishing of sentient beings is grounded in the biological fact that the discrete organism is the principal target of natural selection and social evolution, not the group. We are a social species—we need and enjoy the presence of others in groupings such as families, friends, and assorted social consortia—but we are first and foremost individuals within social groups and therefore ought not to be subservient to the collective. Making sacrifices for one's social group is not the same as being sacrificed for the group.

This drive to survive is part of our essence, and therefore the freedom to pursue the fulfillment of that essence is a natural right, by which I mean it is universal and inalienable and thus not contingent only upon the laws and customs of a particular culture or government. Natural rights theory arose during the Enlightenment to counter the belief in the divine right of kings, and became the basis of the social contract that gave rise to democracy, a superior system for the protection of human rights. This is what the English philosopher John Locke had in mind in his 1690 Second Treatise of Government (written to rebut Sir Robert Filmer's 1680 Patriarcha, which defended the divine right of kings) when he wrote: "The state of nature has a law to govern it, which obliges every one: and reason, which is that law, teaches all mankind, who will but consult it, that being all equal and independent, no one ought to harm another in his life, health, liberty, or possessions." The social contract entered into freely, Locke argued, is the best way to ensure our natural rights.

In rights language, the individual is imbued with personal autonomy. As a natural right, the personal autonomy of the individual gives us criteria by which we can judge actions as right or wrong: do they increase or decrease the survival and flourishing of individual sentient beings? Morality is not arbitrary, relative, or completely culture-bound. Morality is universal. We are all born with a moral sense, with moral emotions that guide us in our interactions with other people, and that are influenced by local culture, customs, and upbringing. Nature endowed us with the capacity to feel guilt for the violation of promises and social obligations, for example, but nurture can tweak the guilt dial up or down. Thus morality is real, discoverable, "out there" in nature, and "in here" as part of our human nature. From these facts we can build a science of morality—a means of determining the best conditions to expand the moral sphere and increase moral progress through the tools of reason and science.


Understanding the nature of things and the causes of effects is what science is designed to do, and ever since the Scientific Revolution there has been a systematic effort by thinkers in all fields to apply the methods of science—which include the philosophical tools of reason and critical thinking—to understanding ourselves and the world in which we live, including and especially the social, political, and economic worlds, with an end toward the betterment of humanity. This effort has produced a worldview known as Enlightenment Humanism (or secular humanism, or simply humanism), which, unlike most other worldviews, is more a method than an ideology; it is a means of solving problems more than it is a set of doctrinaire beliefs. Humanism, as its name implies, is—and ought to be—concerned with the survival and flourishing of humans, and its methods of reason and science are directed at figuring out how best to do that. Thus the goal of a science of morality is—and ought to be—to determine the conditions under which humans and, by extension, other sentient beings best prosper. To that end I need to define what I mean by science and reason.


Science is a set of methods that describes and interprets observed or inferred phenomena, past or present, and is aimed at testing hypotheses and building theories. By set of methods I mean to emphasize that science is more of a procedure than it is a set of facts, and to describe and interpret them means that the facts do not just speak for themselves. Observed or inferred phenomena means that there are some things in nature that we can see, such as elephants and stars, but other things that we must infer, such as the evolution of elephants and stars. Past or present means that the tools of science can be used to understand not only phenomena occurring in the present, but in the past as well. (The historical sciences include cosmology, paleontology, geology, archaeology, and history, including and especially human history.) Testing hypotheses means that for something to be truly scientifically sound it must be testable, such that we can confirm it as probably true or disconfirm it as probably false. Building theories means that the aim of science is to explain the world by constructing comprehensive explanations from numerous tested hypotheses.

Defining the scientific method is not so easy. The process involves making observations and forming hypotheses from them, then making specific predictions based on those hypotheses, then making additional observations to test those predictions to confirm, disprove, or falsify the initial hypotheses. The process is a constant interaction of making observations, drawing conclusions, making predictions, and checking them against the evidence. But note that data-gathering observations are not made in a vacuum. The hypotheses shape what sort of observations a scientist will make, and these hypotheses are themselves shaped by education, culture, and the particular biases of the observer. Observation is key. The British astronomer Sir Arthur Stanley Eddington employed a legal metaphor to capture the sentiment: "For the truth of the conclusions of physical science, observation is the supreme court of appeal." All facts in science are provisional and subject to challenge and change, therefore science is not a "thing" per se; rather it is a method of discovery that leads to provisional conclusions.


Reason is the cognitive capacity to establish and verify facts through the application of logic and rationality, and to make judgments and form beliefs based on those facts. Rationality is the application of reason to form beliefs based on facts and evidence, instead of guesswork, opinions, and feelings. That is to say, the rational thinker wants to know what is really true and not just what he or she would like to be true.

However, as several decades of research in cognitive psychology has shown, we are not the rationally calculating beings we'd like to think we are, but are instead very much driven by our passions, blinded by our biases, and (for better or worse) moved by our moral emotions. The confirmation bias, the hindsight bias, the self-justification bias, the sunk-cost bias, the status-quo bias, anchoring effects, and the fundamental attribution error are just a few of the many ways that our brains work to convince us that what we want to be true is true—regardless of the evidence—in a general process called "motivated reasoning." Nevertheless, the capacity for reason and rationality is within us as a feature of our brains that evolved to form patterns and make connections (it's called learning) in the service of survival and flourishing in the environment of our evolutionary ancestry. Reason is part of our cognitive makeup, and once it is in place it can be put to use in analyzing problems it did not originally evolve to consider. Pinker calls this an open-ended combinatorial reasoning system that "even if it evolved for mundane problems like preparing food and securing alliances, you can't keep it from entertaining propositions that are consequences of other propositions." This ability matters for morality because "if the members of species have the power to reason with one another, and enough opportunities to exercise that power, sooner or later they will stumble upon the mutual benefits of nonviolence and other forms of reciprocal consideration, and apply them more and more broadly."

Drawing inferences about the movement of animals from their tracks—as hunter-gatherer trackers do—has obvious survival advantages, and we have been able to apply those inferential skills to everything from driving to the store to flying rockets to the moon. Historian of science and professional animal tracker Louis Liebenberg has, in fact, argued that our ability to reason scientifically is a by-product of fundamental skills for tracking game animals that our ancestors developed. Liebenberg's analogy between tracking and the scientific method is revealing: "As new factual information is gathered in the process of tracking, hypotheses may have to be revised or substituted by better ones. A hypothetical reconstruction of the animal's behaviors may enable trackers to anticipate and predict the animal's movements. These predictions provide ongoing testing of hypotheses." Liebenberg distinguishes between systematic tracking ("the systematic gathering of information from signs, until it provides a detailed indication of what the animal was doing and where it was going") and speculative tracking ("the creation of a working hypothesis on the basis of initial interpretation of signs, knowledge of the animal's behavior and knowledge of the terrain" that leads to hypotheses that are tested and, if not confirmed, to new hypothetical reconstructions of the animal's whereabouts). Speculative tracking also involves another cognitive process called "theory of mind," or "mind reading," in which trackers put themselves into the mind of the animal they are pursuing and imagine what it might be thinking in order to predict its actions.

Based on archaeological and anthropological evidence Liebenberg estimates that humans have been hunting and using systematic tracking for at least two million years (as far back as Homo erectus), and speculative tracking for at least one hundred thousand years. Whenever these cognitive capacities arose, once the neural architecture is in place to deduce, say, that a lion slept here last night, a person can substitute lion with any other animal or object and can swap "here" with "there" and "last night" with "tomorrow night." The objects and time elements of the reasoning process are interchangeable. In a modern example, once you've mastered the multiplication tables and you know that 7 × 5 = 35, you can infer that 5 × 7 is also 35 because 5 and 7 are interchangeable in the equation. This interchangeability is a byproduct of neural systems that evolved for basic reasoning abilities such as tracking animals for food.


Excerpted from The Moral Arc by Michael Shermer. Copyright © 2015 Michael Shermer. Excerpted by permission of Henry Holt and Company.
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Table of Contents

Prologue: Bending the Moral Arc 1

Part I: The Moral Arc Explained
1. Toward a Science of Morality 11
2. The Morality of War, Terror, and Deterrence 55
3. Why Science and Reason Are the Drivers of Moral Progress 103
4. Why Religion Is Not the Source of Moral Progress 149

Part II: The Moral Arc Applied
5. Slavery and a Moral Science of Freedom 189
6. A Moral Science of Women's Rights 213
7. A Moral Science of Gay Rights 240
8. A Moral Science of Animal Rights 259

Part III: The Moral Arc Amended
?9. Moral Regress and Pathways to Evil 297
10. Moral Freedom and Responsibility 333
11. Moral Justice: Retribution and Restoration 355
12. Protopia: The Future of Moral Progress 397

Notes 441
Bibliography 497?
Acknowledgments 527?
Index 531

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