An Introduction to Evolutionary Ethics E-Book

Scott M. James

• Herausgeber: John Wiley & Sons
• Kategorie: Geisteswissenschaft
• Sprache: Englisch

Seitenzahl: 435

Veröffentlichungsjahr: 2010

Beschreibung

Offering the first general introductory text to this subject, the timely Introduction to Evolutionary Ethics reflects the most up-to-date research and current issues being debated in both psychology and philosophy. The book presents students to the areas of cognitive psychology, normative ethics, and metaethics.

• The first general introduction to evolutionary ethics
• Provides a comprehensive survey of work in three distinct areas of research: cognitive psychology, normative ethics, and metaethics
• Presents the most up-to-date research available in both psychology and philosophy
• Written in an engaging and accessible style for undergraduates and the interested general reader
• Discusses the evolution of morality, broadening its relevance to those studying psychology

Leseprobe

This edition first published 2011

© 2011 Scott M. James

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Library of Congress Cataloging-in-Publication Data

James, Scott M.

An introduction to evolutionary ethics / Scott M. James.

p. cm.

Includes bibliographical references and index.

ISBN 978-1-4051-9397-9 (hardcover : alk. paper) – ISBN 978-1-4051-9396-2

(pbk. : alk. paper)

1. Ethics, Evolutionary–Textbooks. I. Title.

BJ1311.J36 2011

171′.7–dc22

01    2011

To M.B.

Contents

Cover

Title Page

Copyright

Dedication

Introduction: A Philosopher and a Biologist Walk into a Bar ...

Part I From “Selfish Genes” to Moral Beings: Moral Psychology after Darwin

1 Natural Selection and Human Nature

1.1 The Basic Story

1.2 Some Common Misunderstandings

1.3 Mother Nature as Tinkerer

1.4 Evolutionary Psychology and Human Nature

1.5 An Evolved Mental Tool-Box

1.6 Some (More) Common Misunderstandings

1.7 Conclusion

Further Reading

2 The (Earliest) Roots of Right

2.1 Together We Stand?

2.2 Inclusive Fitness and the “Gene's-Eye” Point of View

2.3 Love Thy Neighbor – But Love Thy Family First

2.4 False Positives and Core Systems

2.5 A Quick Note on “Altruism”

2.6 Reciprocal Altruism

2.7 Conclusion

Further Reading

3 The Caveman's Conscience: The Evolution of Human Morality

3.1 What Makes Moral Creatures Moral

3.2 The Evolution of Morality

3.3 Explaining the Nature of Moral Judgments

3.4 Conclusion

Further Reading

4 Just Deserts

4.1 The Ultimatum Game

4.2 The Public Goods Game

4.3 Winners Don't Punish

4.4 The Benefits of Guilt

4.5 A Lamb among Lions?

4.6 An Explanation for All of Morality?

4.7 Universal Morality or Universal Reason?

4.8 Conclusion

Further Reading

5 The Science of Virtue and Vice

5.1 Distress Test

5.2 Mind-Reading

5.3 “Them's the Rules”

5.4 Moral Innateness and the Linguistic Analogy

5.5 Switchboards, Biases, and Affective Resonances

5.6 Non-Nativist Doubts

5.7 Conclusion

Further Reading

Part II From “What Is” to “What Ought To Be”: Moral Philosophy after Darwin

6 Social Harmony: The Good, the Bad, and the Biologically Ugly

6.1 From the Great Chain of Being, to the Tree of Life, to Morality

6.2 Uprooting the Tree of Life

Further Reading

7 Hume's Law

7.1 Deductively Valid Arguments

7.2 You Can't Get Out What You Don't Put In

7.3 “Of the Last Consequence”

7.4 Blocking the Move from Might to Right

7.5 Darwinism and Preserving the Human Species

7.6 Conclusion

Further Reading

8 Moore's Naturalistic Fallacy

8.1 The Open Question Test

8.2 Failing the Open Question Test: Desiring to Desire

8.3 Failing the Open Question Test: Spencer

8.4 Failing the Open Question Test: Wilson

8.5 Conclusion

Further Reading

9 Rethinking Moore and Hume

9.1 Some Preliminary Doubts about the Open Question Test

9.2 What Things Mean vs. What Things Are

9.3 Implications for Social Darwinism

9.4 Forays across the Is/Ought Gap: Searle

9.5 Forays across the Is/Ought Gap: Rachels

9.6 Conclusion

Further Reading

10 Evolutionary Anti-Realism: Early Efforts

10.1 This Is Your Brain on God

10.2 Preliminaries

10.3 Wilson

10.4 The Argument from Idiosyncrasy

10.5 The Argument from Redundancy

10.6 Causation, Justification, and … a Rotting Corpse

10.7 Conclusion

Further Reading

11 Contemporary Evolutionary Anti-Realism

11.1 Napoleon Pills

11.2 A Darwinian Dilemma

11.3 Conclusion

Further Reading

12 Options for the Evolutionary Realist

12.1 Option 1: Learning Right from Wrong

12.2 Option 2: Response Dependency

12.3 Option 3: Virtue Ethics Naturalized

12.4 Option 4: Moral Constructivism

12.5 Objections to the Realist Options

12.6 Conclusion

Further Reading

Notes

References

Index

Introduction: A Philosopher and a Biologist Walk into a Bar …

Any animal whatever, endowed with well-marked social instincts, the parental and filial affections being here included, would inevitably acquire a moral sense or conscience, as soon as its intellectual powers had become as well developed, or nearly as well developed, as in man.

(Charles Darwin, The Descent of Man)

In 1975 the Harvard entomologist and father of sociobiology E.O. Wilson famously suggested that “scientists and humanists should consider together the possibility that the time has come for ethics to be removed from the hands of philosophers and biologicized” (Wilson 1975: 520). Philosophers, apparently, had had their shot – and didn't have much to show for their efforts. Now biologists, armed with a comprehensive understanding of human evolution, were standing by to explain that most human of traits: a sense of right and wrong. But in their enthusiasm, Wilson and his sympathizers had failed to articulate exactly what “biologicization” meant. For despite the impression left by Wilson's suggestion, it was immediately pointed out (by philosophers, alas) that biology could play – and has played – a variety of roles in moral theory, ranging from the uncontroversial to the highly contentious.

What this means, first and foremost, is that the real question is not: Does biology play some role in the explanation of morality? (Surely it plays some role.) The real question is: What sort of role does biology play in the explanation of morality? How, in other words, should the story of human evolution influence what we think about our moral lives – our moral judgments, our moral feelings, our moral differences, our tendency to avoid wrongdoing, our admiration of self-sacrifice, our hostility toward wrongdoers, and so on? This question, roughly stated, lies at the heart of what we think of as evolutionary ethics.

As a first step toward understanding the many ways in which biology might influence moral theory, consider the following menu of options proposed by Philip Kitcher 1985:

1 Explaining our moral psychology. Biology might provide (at least some part of) an evolutionary account of how our species came to acquire moral concepts and make moral judgments. Biology might explain, that is, how recurrent features of our ancestral environment (for example, social or moral features) led some of our ancestors to think in moral terms.

2 Constraining or expanding our moral principles. Biology might offer new insights into human nature that may constrain or expand the moral principles we already accept. We may learn, for example, that humans tend to value some practices that ethicists had not previously recognized; this in turn might expand the practices that ought to be morally protected.

3 Determining the metaphysical status of moral properties. Biology might settle, once and for all, questions about morality's objectivity. For example, some have argued that evolution “fooled” us into believing that some acts really are wrong (where nothing in reality is wrong), since believing as much would have promoted cooperation, which in turn would have advanced our ancestors' biological fitness.

4 Deriving new moral principles from evolution.Biology alone might tell us what our moral obligations are. Social Darwinists, for example, argue that since the survival of our ancestors depended critically on promoting “social harmony,” we thus have a moral obligation to promote social harmony.

As you can see, “biologicizing” ethics can mean different things to different people. The philosophical significance of this point cannot be overstated: a commitment to one project does not necessarily entail a commitment to any other project. For example, one might argue that the story of human evolution explains in part how we came to have the moral psychology that we have (option 1 above), but deny that the nature of moral obligation is determined by this (or any other) biological fact (option 3). To see why, consider an analogy. Psychologists attempting to understand the nature of visual perception study how the body's visual system – a system whose structure was refined over thousands of generations – processes an external stimulus, such as a cat. What psychologists expect to learn (and have learned) is something about visual processing; what they do not expect to learn is something about the nature of cats. Once identified, the lesson is obvious: if you want to know what makes a cat a cat, ask a zoologist, not a psychologist. Similarly, one might argue that moral psychologists expect to learn something about the processing of moral and social “information”; they do not expect to learn something about the nature of morality itself. If you want to know what makes wrong acts wrong, ask a moral philosopher, not a psychologist. Or so some have argued.

To take another example, one could argue that biology indeed uncovers facts about human nature that bear on our moral obligations (option 2), but deny that our moral obligations are derived from these (or any) biological facts (option 4). Consider another analogy. Some evolutionary psychologists reason that since our early ancestors faced the recurrent problem of getting enough calories from what they ate, one adaptive solution would have been to develop an innate craving for fatty foods. (In case, being from another planet, you doubt we have such cravings, anthropologists have indeed observed this tendency across cultures.) The point, however, is this: even if it is true that our evolutionary past has disposed us to crave and consume fatty foods whenever available, does it seem correct to conclude that we ought to crave and consume fatty foods whenever available? Surely not! If the 2004 film Super Size Me (documenting one man's ill-fated attempt to subsist on a McDonald's-only diet) demonstrated anything, it was that we ought to resist our craving for and consumption of fatty foods. How is this relevant to biology's role in moral theory?

Suppose it is true (as anthropologists have noted) that humans tend to discriminate against outsiders. We are, it appears, far less likely to assist strangers than those who are near and dear. Does this mean that we ought to discriminate against outsiders? Let's test the idea. Suppose you are visiting another country and happen to fall in a shallow pond. Because you can't swim, your life is suddenly threatened. Now, does the native observing all this have any reason to toss you the life preserver at his feet? I have a hunch that you'll say (with confidence) “Yes.” Why? Because (you might argue) the fact that you are an outsider is morally irrelevant to the native's reason to assist you. Indeed, we might go further and maintain that we ought to resist our biologically based disposition to discriminate against outsiders. But if this is right, then we must reject the idea that our moral obligations are derived from our biologically given dispositions. Or so some have argued.

The overarching point, however, is worth repeating: offering support to the “biologicization” of ethics settles almost nothing. Our evolutionary past is relevant to understanding our present moral experience (at least in the secular moral tradition), but this leaves open the precise nature of that relationship. Hence, our task is to look hard at the details – both biological and philosophical. And that's what we'll do throughout this book.

∗∗∗

The book is divided into two thematic parts, each of which is relatively freestanding. Part I explores the ways in which evolution may have shaped our moral psychology. We will explore some contemporary work in evolutionary psychology, anthropology, primatology, and even neurobiology. We will set to one side – as far as possible – questions about the nature of morality itself and focus instead on how the processes of evolution by natural selection could have produced creatures that not only help others, but often do so because they are, as Darwin noted, “impelled simply by the deep feeling of right or duty.”

In part II we will move to the normative or evaluative realm by asking: What actions or practices, if any, does our evolutionary past justify? Social Darwinists (and even some contemporary philosophers) argue that our biological past is a source of both psychological descriptions and moral norms. That is, evolution tells us not only how things are (biologically speaking), but also how things ought to be (morally speaking). Such efforts to derive norms from descriptive facts confront some standard objections (one of which we discussed earlier), so we will explore the extent to which these views can survive these objections.

We will also tackle in part II the question of morality's objectivity. Some of the most exciting and provocative arguments in contemporary moral philosophy contend that believing in “moral facts” is unjustified once we have a complete descriptive account of the origins of our moral psychology. The reason, according to some, is that evolution explains all that needs explaining. Our feeling – indeed, our thinking – that some acts are objectively wrong is explained by the need for cooperation among our ancestors. This, then, is supposed to undercut any independent reason to suppose that moral properties, such as wrongness, really exist. We'll look at some objections to these arguments and consider, too, realist (or quasi-realist) alternatives to the anti-realist view just discussed.

It is important to emphasize, however, that although discussions in one part of the book may have implications for other parts, the observations made several paragraphs back should caution us against hasty inferences. There is an impressive array of combinations in logical space. We would not want to prejudge which combination is most plausible.

∗∗∗

Let me acknowledge, in closing, several issues that one might have expected to find discussed in a book on evolutionary ethics – but which will not receive attention here. First, there exists a pervasive (some might say, regrettable) temptation to link discussions of evolution with atheism and atheism with immorality. Thus one might regard the very idea of “evolutionary ethics” as contradictory, since (a) evolution eliminates God's role in humanity's affairs, and (b) as a God-less humanity lacks any reason to be moral, the choice is evolution or ethics – but not both. As tempting as this bit of reasoning may be, it's deeply problematic. Neither (a) nor (b) is obvious, and efforts to make them obvious would involve considerable argumentation that would lead us into distant philosophical terrains. That, at any rate, would not be a book on evolutionary ethics, but a book on philosophy of religion and secular ethical theory. That said, it should be apparent from our discussion thus far that we will be assuming that the human species possesses many of its traits (including some psychological traits) by dint of evolutionary forces. But accepting this assumption does not entail acceptance of atheism or moral nihilism.

A second, perhaps more subtle, discussion one might have expected from a book on evolutionary ethics is a discussion of biological or genetic determinism. The concern, as I understand it, is as follows. Since (1) our evolutionary past determines our individual genetic makeup, (2) our genetic makeup determines our behavior, in a suitably strong sense, and (3) we cannot be morally responsible for behavior that is determined, our evolutionary past undermines moral responsibility. This argument, like the previous one, may have some initial appeal. But the reason I've decided not to include it here is that, on reflection, it goes wrong at pretty much every turn. Claims (1) and (2), as we'll see in the coming chapters, result from confusion about evolutionary theory. As any biologist will tell you, nature alone determines almost nothing – just as nurture alone determines almost nothing. These two are not competitors, they're counterparts. Even if your genetic makeup were not distinct from any other (as in fact it is), a dizzying variety of environmental differences will distinguish you from others. But setting even that aside, genes are not destiny. While evolution may (may) have disposed you to have certain emotions or preferences, you retain the ability to choose whether or not to act on those preferences.1 You can say to yourself: ‘As much as I would like to give this job to my son, I have to be fair to all the applicants, so I had better not.’ Even (3) is not immune from criticism (though I'll leave that for another time).

Suffice it to say that the issue of genetic determinism has unfortunately become something of a bogeyman haunting discussions of evolution and human nature.2 And while I could add one more stone to the mountain of criticism, I prefer to let that mountain speak for itself. So for the reader harboring lingering doubts about the issue, I have (alas) nothing to offer.3 There are enough battles to sort through without revisiting that long-dormant one. As we speak, new insights into the evolutionary underpinnings of human nature are being uncovered, but the pace of moral theory is struggling to keep up. Part of the problem, as we've just seen, is running together the variety of ways in which biology might influence moral theory. Now that we've sorted that out, we can begin to close the gap that separates our biological understanding of ourselves from our moral understanding of ourselves.

Part I

From “Selfish Genes” to Moral Beings: Moral Psychology after Darwin

You get a lot more with a nice word and a gun than with a nice word.

(Al Capone)

In the opening passages of The Selfish Gene, Richard Dawkins has us imagine a gangster (let's call him Sonny) who managed to live a long and prosperous life in the Chicago underworld. Dawkins asks us to consider the kinds of qualities Sonny must have had to survive so long in such an environment. Well, we might reasonably guess that Sonny was not uniformly benevolent or generous or tenderhearted. At the very least, Sonny must have been tough. He must have been keenly aware of others' loyalty. He must have been quick to spot deception and merciless with competitors. He must have been, according to Dawkins, “ruthlessly selfish” at the core. (Fans of The Sopranos will have no trouble getting the picture.) The point of Dawkins' story, however, is that Sonny is our mirror: insofar as we're prepared to ascribe these qualities to Sonny, we should be prepared to ascribe these same qualities to ourselves. We are, after all, survivors of our own rough neighborhood. Here's how Dawkins explains it.

Our genes have survived millions of years in a highly competitive environment. But this was possible only because genes are self-serving. And creative. Along the way genes developed ingenious vehicles to ensure their survival and reproduction. Some of those vehicles are quite simple. Others verge on the miraculous. But simple or miraculous, the underlying idea is the same: the living forms we see around us – birds and bees, ferns and foxes – are, in the end, “gene machines.” And so it is with us: Human beings are just another kind of gene-machine. Although we dress better than mollusks and make better sandwiches than baboons, we are in principle no different from them. We're just more sophisticated means of making more genes; after all, we are only here for their sake. But, as Dawkins notes, since “gene selfishness will usually give rise to selfishness in individual behavior,” we have every reason to believe that, despite appearances to the contrary, each of us is ruthlessly selfish at the core. “Scratch an altruist,” writes the biologist Michael Ghiselin, “and watch a hypocrite bleed” (Ghiselen 1974: 274). Each of us harbors our own little inner gangster. Almost apologetically, Dawkins concludes: “Much as we might wish to believe otherwise, universal love and the welfare of the species as a whole are concepts that simply do not make evolutionary sense.”

And yet, when we step back and observe ourselves, there is something about Dawkins' story that doesn't make sense. For if he's correct, then people would never have an interest in doing the right thing (never mind knowing what the right thing to do is); people would never admire virtue, rise up against injustice, or sacrifice their own welfare to benefit strangers. If human beings are ruthlessly selfish at the core, then we should find unintelligible Adam Smith's observation that man possesses capacities “which interest him in the fortunes of others, and render their happiness necessary to him, though he derives nothing from it, except the pleasure of seeing it” (Smith 2010/1759: 9). But we don't find Smith's observation unintelligible. Even the cynic has to admit that people do sometimes have an abiding interest in doing the right thing (even those who don't know what the right thing to do is). A surprising number of people work on behalf of the poor and disenfranchised. Consider that in 2004 private American citizens gave more than $24 billion of their own money to aid complete strangers (Hudson Institute 2007: 14). This hardly sounds like the work of a band of “ruthlessly selfish” creatures. At the very least, people seem to care about how their actions will be received by others. More striking still is the fact that people seem to care deeply about acting in accord with their own conscience. One of the great themes of literature is the psychic peril of “getting away with the crime”: merely knowing that we've acted wrongly can be its own punishment. So perhaps the analogy with the gangster is inapt. Perhaps humans transcend their evolutionary roots in a way that cannot be explained by biology. Indeed, perhaps we've hit upon what separates humans from the rest of the natural world: our ability to grasp a (the?) moral order. This would render biology irrelevant to the study of moral psychology.

So where does this leave us? I began with a biological picture of human beings that appeared to exclude the moral. I then presented a moral picture of human beings that appeared to exclude the biological. We thus have a decision to make. We can: (a) embrace the biological picture and explain away the moral part of ourselves; (b) embrace the moral picture and explain away the biological part of ourselves; or (c) reconcile the biological and moral pictures. As implausible as this last option may sound, a growing number of theorists from across the spectrum are throwing their weight behind it. (Not that the idea doesn't sound odd: “In the same way that birds and airplanes appear to defy the law of gravity yet are fully subjected to it, moral decency may appear to fly in the face of natural selection yet still be one of its many products,” writes the renowned primatologist Frans de Waal 1996: 12.) Indeed, one of the aims of this book is to defend the idea that moral decency does have its roots in biology.

In addition to the growing empirical and philosophical body of work outlining various means of reconciling our moral and biological natures, there is the cost of embracing one of the other options. On the one hand, we are moving inexorably towards a picture of human nature that is richly informed by evolutionary theory; robust trends are appearing in anthropology, sociology, psychology, economics, and philosophy. It is difficult to imagine, then, abandoning biology in any serious quest to understand human nature. On the other hand, any picture of human beings that leaves out our moral sensibility is fatally incomplete. This isn't to say that we are uniformly good or even decent. It is to say that our practical lives are indelibly marked by moral thought: we make moral judgments; we deliberate over what the right thing to do is; we experience moral emotions (e.g. guilt and benevolence); we punish wrongdoers and reward the virtuous.

Hence, if we are not yet prepared (as theorists) to overlook our moral natures or the power of biological explanations, then we assume the burden of reconciliation: How can we bring these two pictures of ourselves into alignment? Attempting an answer to this question is the task of the first part of this book. I say “attempting an answer” because the state of the field (what might be called evolutionary moral psychology) is still quite young – and speculative. Although there appears to be consensus at some very basic levels, as you'll see, there remain deep disputes. Much of our work will consist in surveying these disputes. But I will also attempt to offer what I take to be more promising lines of research. After all, I have my own theories regarding the evolution of morality. At any rate, the next five chapters are united around two general questions: (1) Why might natural selection have favored hominids who thought and (sometimes) behaved morally? And (2) How did natural selection fashion – out of preexisting materials – hominids who thought and behaved morally?

Chapter 1

Natural Selection and Human Nature

In a single stroke, the idea of evolution by natural selection unifies the realm of life, meaning and purpose with the realm of space and time, cause and effect, mechanism and physical law. It is not just a wonderful idea. It is a dangerous idea.

(Daniel Dennett, Darwin's Dangerous Idea)

To be human: To be the place where the falling angel meets the rising ape.

(Terry Pratchett, Hogfather)

In order to get some traction on the question of natural selection's role in the development of our moral psychology, we first need to refresh ourselves on the basics of Darwin's theory. In this chapter we review some of the basic features of evolution by natural selection. We will not bother too much with the details. What's important is to highlight the general principles that have led some moral psychologists to claim that evolution played a critical role in shaping our moral mind. I'll start with the general story, which is actually quite easy to tell. Then, with that story firmly in place, I'll dispel some common misconceptions about the view. In the final sections, I'll explore the ways in which this story has been extended to psychology, where it is claimed that, like our bodies, our minds contain specialized adaptations.

1.1 The Basic Story

At the center of what might be called the Darwinian Revolution, amid the myriad details and disputes, refinements and revisions, field tests and computer models, is a very simple, very elegant idea. Here's a glimpse of it in Darwin's own words:

More individuals are born than can possibly survive. A grain in the balance will determine which individual shall live and which shall die, – which variety or species shall increase in number, and which shall decrease, or finally become extinct. (Darwin 2003/1859: 467)

Buried in this passage are three conditions on which the entire edifice of evolution by natural selection stands: variation, differential reproduction, and inheritance. Let's look closely.

One background assumption, left unstated in the passage, is that the number of reproducers in a given population will eventually outgrow an environment's resources; hence, “more individuals are born than can possibly survive.” But, Darwin implies, all individuals are not created equal: speed, strength, coloration – these vary within a population. Some (but only some) of these variations – in the particular environment individuals inhabit – will over time alter an individual's reproductive success; there will be, that is, differential reproduction within a population. For example, the individual moth that happens to be grey tends to be overlooked by predators in her environment, whereas the individual moth that happens to be white makes for an easy meal in that same environment. That tiny difference in color, that “grain in the balance,” may well affect not only that individual's chances of survival and reproduction, but the makeup of the species as a whole. Why? Because if we assume that variation in color can be inherited, then offspring will tend to exhibit that color variation as well. And since grey moths have a small reproductive advantage over white moths, grey moths (all things being equal) will come to dominate the population. Mother Nature will “select against” white moths in that environment. In sum, some variations that occur naturally among reproducing organisms improve an individual's rate of reproductive success in relation to its neighbors; when these fitness-enhancing variations are passed on to offspring, you have evolution by natural selection.1

As simple and mindless as this process may sound, its power is hard to overstate. The evolutionary biologist Theodosius Dobzhansky went so far as to claim that “nothing in biology makes sense except in the light of evolution” (1964: 449). First, the theory offers a direct and uncluttered explanation for much of the diversity of organic structures we observe across time and across the biological world, an explanation that does not draw on anything more controversial than, say, the workings of genes. With enough time, the pressures of an unforgiving environment – together perhaps with picky neighbors – will yield any number of exotic forms, from flying squirrels to jellyfish to redwoods.

Second, the theory delivers what was once thought undeliverable: an explanation of design that does not depend on a designer. Who could deny that the human eye or the finch's beak is exquisitely suited to its environment? It would seem from any commonsense perspective that that fit had to be the result of some kind of engineer, someone who understood both how the design would integrate with the other workings of the organism and how it would mediate the organism's interaction with its environment. But that perspective is distorted by, among other things, our place in time. Were we capable of “rolling back the tape” and observing each generation, with its incremental alterations and minor reproductive successes, we would find the development of the human eye, for example, almost unremarkable. The philosopher Daniel Dennett (1995) compares the process to selecting a tennis champion. How does every tennis tournament always select a champion? Easy, she's the last person standing after all the rounds. Remember: we do not see the 99 percent of genetic mutations that do not advance an organism's fitness; we only see the “winners.” Success in design is inevitable and ubiquitous for the simple reason that creatures ill suited to their environment have, as the philosopher W.V. Quine put it, “a pathetic but praiseworthy tendency to die before reproducing their kind” (1969: 126).

Finally, the core logic of evolutionary explanations is not limited to the shape of organs or the strength of bones, but extends rather smoothly to observable behaviors. Beginning in the 1960s, biologists following the work of Konrad Lorenz and Nikolaas Tinbergen developed methods of analyzing the underlying structure of animal behavior, a field that came to be known as ethology. Here, critical focus was directed on the adaptive purpose(s) of certain behaviors, for example, the phenomenon of “imprinting” observed in ducklings.2 The assumption among ethologists was that there existed a series of evolutionary events – or adaptive pressures – that ultimately led to the behavior. This would explain, if anything did, what the behavior was for. And this in turn might aid in understanding the developmental influences that lead to the expression of the behavior in individuals.

From here, it is only a few short steps back to our main subject: the human moral sense. (For the time being, think of a moral sense as a tendency to make moral judgments and experience moral sentiments.) If – and I stress the if – one wanted to argue that our moral sense is the product of evolution by natural selection, the general shape of the argument must look something like the following. Through the process of genetic variation, some individual (presumably some early hominid) developed something approximating a moral sense. While perhaps only slightly distinct from its evolutionary precursor, that sense enabled its possessor to survive and reproduce at a rate that exceeded, if only slightly, the rate of her neighbors. Left unchecked, the process of natural selection yielded a population dominated by individuals who possessed this moral sense.

Let me emphasize, however, two things: first, this argument amounts to little more than a general schema; all of the details needed to make this argument remotely plausible have been left out. In later chapters we will explore these details. Second, one could maintain that evolution by natural selection contributed to the development of our moral sense, but only indirectly. Two positions present themselves.

One of the positions that we will discuss later asserts that our moral sense was, if you will, a “by-product” of some other system that was directly selected for. As a point of comparison, consider the color of human blood. No one seriously believes that the redness of human blood was directly selected for. What was directly selected for was the oxygen-carrying properties of blood; the redness “came along for free.” That was an accidental property of blood.3 In the same way, some wish to claim that our moral sense was an accidental property of other cognitive adaptations – for example, our capacity to reason about the consequences of our actions.

A distinct but related position states that our moral sense did evolve according to the laws of natural selection; however, the function that our moral sense originally served has been replaced (due to changes in environmental circumstances) by a more recent function, which in turn can alter its structure. A popular example of this kind of biological sleight of hand is the structure of the human lungs. Some biologists insist that human lungs originally evolved, millennia ago, to aid predatory fish in pursuing prey (Farmer 1997). But once the ancestors of these fish began their forays onto land, those “swim bladders” were well suited to respiration. Thus one might argue that our moral sense may have originally evolved to serve a purpose entirely unrelated to its present purpose.4 The exact structure of these views will have to wait. In the meantime, let me warn against some common misunderstandings of Darwin's theory.

1.2 Some Common Misunderstandings

The theory of evolution by natural selection does not entail the claim that every feature of every organism is an adaptation. It is consistent with the theory that some (some insist on many) of the organic structures we observe are not the result of the pressures of natural selection. Some are the result of random genetic mutation; others are the result of what biologists call founder effects, according to which a dominant characteristic (e.g. coloration) of an isolated sub-population is the result of an arbitrary feature possessed by the founders of this sub-population. So, for example, a group of green-winged finches becomes separated from the main colony of finches, only a fraction of the birds in which are green-winged. Assuming “green-wingedness” does not influence reproductive success, we will nevertheless observe “green-wingedness” come to dominate this population even though this form of evolutionary change is not the result of natural selection. Some organic changes are the result of genetic bottlenecks. Like founder effects, genetic bottlenecks occur when a population shrinks rather suddenly (e.g., following an earthquake), leaving only a subset of the genes of the original population.

It's worth pausing a moment to point out what these alternative processes of evolution might mean for our main inquiry. One could, for example, claim that our moral sense evolved, but that its evolution was not the result of natural selection. According to a story like this, our moral sense was not an adaptation. Its existence might be the result of a process no fancier than that which produced “green-wingedness.” If this were the case, it would be fruitless to search for the (biological) purpose of our moral sense. It has no purpose. As we move forward, it's important to keep these alternatives in sight.

Another common misunderstanding of Darwin's theory is that evolutionary change is, in some sense, forward-looking, or deliberate. Part of the problem stems from terminology: to say that over time organisms adapt to their environments strongly invites the mistaken idea that Mother Nature – or the organisms themselves – actively solve adaptive problems by altering their structure. In the standard example, the giraffe reasoned that reaching the leaves in the high trees required a long neck, and so – voilà! – a long neck. This of course is nowhere near the truth. We have to remember that natural selection can only “act” on those variants that happen to exist, and which variants happen to exist is quite arbitrary, since variation is by and large the result of genetic “errors” during DNA replication. This is not to deny that some organisms are exquisitely suited to their environment. But it is almost always the case that, on much closer inspection, those adaptive “solutions” are surprisingly jerry-rigged: instead of designing the most efficient or reliable or economic solution, Mother Nature appears to have rigged together pieces and parts of other existing designs (a bone here, a ligament there) to enable the organism to get by. Daniel Dennett (1995: 211) refers to them as “perversely intricate solutions.” If the raw material on which natural selection acts is genetic variation, then this is precisely what we should expect to see: tinkering. She may be clever, but Mother Nature is nonetheless a tinkerer.

1.3 Mother Nature as Tinkerer

At least part of the resistance to the idea that our moral minds are the product of natural selection comes from a deep suspicion that natural selection, despite its force, could never lead to a mode of thinking as rich and emotional and powerful as moral thinking. Mother Nature is simply not that clever. One way that biologists have tried to ease this suspicion is by having us think about other more familiar processes that, despite their rigidity, produce quite original and unexpected results. Here's a common method biologists and philosophers use to loosen our resistance:

Your assignment is to compose an original Petrarchan sonnet. In case you've forgotten, a Petrarchan sonnet is a poem consisting of fourteen lines; each line should contain, with only one or two exceptions, ten syllables, where every other syllable is accented. The proper rhyme scheme is: a-b-b-a/a-b-b-a/c-d-e-c-d-e. Although I leave the theme up to you, it is expected that the first eight lines should introduce a problem or dilemma; the remaining six lines should seek to resolve the problem.

I'm going to bet that you would not relish the thought of completing such an assignment. It's just too constricting. Even if you manage to hit upon an agreeable theme rather quickly, what promises to take up all your time is fitting that theme into the poem's rigid confines. Obviously, you can't designate in advance your rhyming words (“bird,” “heart,” “start,” “blurred”) without making your task nearly impossible. Instead, you just have to strike out in a general direction. Put some words on paper and be prepared to make lots of adjustments. You should expect of course that most of your early efforts will have to be trashed. It's not enough to find a word that rhymes with “deranged”; the word has to fit both locally (that is, grammatically) and globally (that is, thematically). In some cases, a particularly effective turn of phrase may necessitate restructuring the entire stanza. As unpalatable as this assignment may seem, I would wager that if you were to stick with it, if you were to wrestle your poetic imagination into the poem's form, you would surprise yourself. You wouldn't necessarily proclaim, “I'm a poet after all!” You would, however, produce some quite original and unpredictable lines, and apart from the music of the poem, they would express some quite original thoughts. (The price of doubting me on this, of course, is writing your own sonnet.) But the reason such an exercise is likely to yield unexpected results lies precisely in the restrictions of the form. Poetic “energy” has to be channeled, often in unnatural directions. The mathematician Stanislaw Ulam observed that poetic form “forces novel associations and almost guarantees deviations from routine chains or trains of thought. It becomes paradoxically a sort of automatic mechanism of originality” (1975: 180). In the process of wearing out the delete key on your computer eliminating all the obvious expressions (simply because they don't fit), eventually something clicks. It fits the meter, it sets up the rhyme, and it advances the larger theme. Ingenious! Moreover, what are the chances you would have come up with that expression in the absence of such restrictions?

The point of this little example is to emphasize the unlikely power of form or law in the creation of solutions. To be sure, writing a sonnet and designing species are dis-analogous in a variety of ways. Most notably, there is no analogy to the role of poet in the case of evolution; the metaphor of “tinkerer” is just that, a metaphor. There is selection going on in both instances, but the most that can be said in the case of evolution is that species are being selected for by the processes outlined above. Still, the metaphor is instructive: Mother Nature “tinkers” with the different designs that genetic mutations make available, just as we would tinker with words in composing a sonnet. Of course, like the vast majority of words you can think of, most organic alterations won't fit within the imposing confines already set up. Such alterations either don't fit locally (they're incompatible with the organism's internal structure) or globally (they decrease an organism's reproductive success relative to its neighbors). But every now and then, a slight modification of existing structure fits. Mother Nature's tinkering pays off. And, as in the case of writing the sonnet, the originality can be breathtaking: webbed feet, echolocation, poisonous venom, photosynthesis. Perhaps even thought.

So maybe we should take Richard Dawkins' advice: “Never say, and never take seriously anyone who says, ‘I cannot believe that so-and-so could have evolved by gradual selection.’ I have dubbed this kind of fallacy ‘the Argument from Personal Incredulity.’ Time and again, it has proven the prelude to an intellectual banana-skin experience” (1995: 70).

In the next section we build on these earlier scientific developments and explore the exciting (and controversial) new field of evolutionary psychology. As the name suggests, evolutionary psychology proposes to study the human mind in the same way that evolutionary biologists study organic form: by applying the principles of Darwinian selection. In this case, the objects of study are patterns of human behavior, patterns of human thought and desire. The study is directly relevant to our main focus, for it is often within the field of evolutionary psychology that some theorists locate the evidence for an evolved moral sense.5

1.4 Evolutionary Psychology and Human Nature

You may have no problem accepting a Darwinian explanation for the structure of the human eye. Ditto for the human lungs, liver, colon, and circulation system. But what about jealousy? What about friendship? What about men's proneness to violence, or women's interest in looking young? What about language? These things, you say, are another matter. Perhaps not, say evolutionary psychologists.

Today, Darwin's ideas about evolution occupy an interesting place. On the one hand, when it comes to explaining the bodily features of human beings (the human heart or the human hip joint), most people have no problem appealing to evolution by natural selection. On the other hand, when it comes to explaining the psychological features of human beings, people resist appealing to evolution by natural selection – if it occurs to them at all. Apparently, there is an explanatory divide between the human body and the human mind. That divide is perpetuated (I suspect) by the weatherbeaten distinction between nature and nurture.

The prevailing assumption is that the human body is as it is by nature (for example, you didn't learn to grow legs instead of fins), whereas the human mind is as it is by nurture. Your attitudes about what makes a desirable mate, for example, were primarily shaped by your environment. That divide between body and mind, however, is eroding. In this section, we explore what some are calling the new science of the mind, evolutionary psychology, which actively seeks to integrate psychology and evolutionary biology.

Contrary to the prevailing assumption, evolutionary psychology maintains that there is a common explanatory framework underlying both human physiology and human psychology: evolution by natural selection. A complete understanding of the human mind, according to evolutionary psychologists, requires understanding the evolutionary pressures that shaped it so many millions of years ago. We do not come into the world as blank slates, as many commonly assume. Instead, they argue, our heads are full of psychological adaptations.

Of course, when asked to think of evolutionary adaptations most of us think of anatomical features like a duck's webbed feet or a lizard's camouflaged skin. According to the standard account, webbed feet initially arose as a result of a genetic mutation; because webbed feet enabled their possessor to out-reproduce its neighbors (all things considered), over time webbed feet spread to the entire population. Evolutionary psychologists are proposing a similar account for mental features. At some point in the distant past, a certain mental system arose in an individual as a result of a genetic mutation; this system altered her psychology – the way she thought or felt or reasoned or desired. And because this system enabled her to out-reproduce her neighbors (all things considered), over time that mental system spread to the entire population. Speaking grandly, we might say that just as webbed feet are part of a duck's nature, so, too, certain ways of thinking or reasoning or desiring are part of human nature.

Returning for a moment to our main theme (i.e. the human moral sense), we can put our question this way: Is having a moral sense part of human nature, where that nature is best explained by evolution by natural selection? As we'll see below, in order to answer that question we will need to look carefully at the kind of adaptive problem (if any) that our moral sense was designed to solve. Webbed feet, for instance, helped solve the problem of efficient movement through water. If our moral sense is indeed an adaptation, then there should be good evidence that possession of such a sense helped to solve (or to solve more successfully than one's neighbors) a particular adaptive problem. But we're getting ahead of ourselves. Let's look more closely at the details of evolutionary psychology.

1.5 An Evolved Mental Tool-Box

Evolutionary psychologists hypothesize that the human mind is equipped with many (some say very many) different evolved psychological mechanisms. Instead of viewing the mind as containing a single all-purpose “problem-solver,” evolutionary psychologists view the mind in roughly the way we view the body. We know the body does not contain a single anatomical mechanism to deal with the body's journey through the world. Rather, it contains different mechanisms to confront different problems: a liver to filter out toxins, lungs to take in oxygen, antibodies to fight off bacteria and viruses, and so on. It's true that each mechanism is profoundly limited in what it can do (your digestive system is a pretty bad listener), but this cost is more than offset by the benefits. With only one task to complete, each system should be able to do it efficiently, economically, and quite reliably.6 And even if other systems break down (you lose your eyesight, for example), most other systems should remain operational.

Evolutionary psychologists contend that this is the way we should understand the human mind.7 Like the body, the mind requires different mechanisms to deal with different tasks. After all, the alternative to this picture – a single, all-purpose psychological mechanism – is, say evolutionary psychologists, hard to accept:

The idea that a single generic substance can see in depth, control the hands, attract a mate, bring up children, elude predators, outsmart prey, and so on, without some degree of specialization, is not credible. Saying that the brain solves these problems because of its “plasticity” is not much better than saying it solves them by magic. (Pinker 1997: 75)

What we're left with, then, is what some psychologists call a “modular” account of the mind: many distinct modules designed to solve many distinct problems. That is, many distinct “tools” to take on many distinct problems. It's an evolutionary account because natural selection is responsible for the design. But what are these modules?

According to David Buss, a leading evolutionary psychologist, an evolved psychological module or mechanism is “a set of procedures within the organism that is designed to take in a particular slice of information and transform that information via decision rules into output that historically has helped with the solution to an adaptive problem” (2007: 52). What does this mean? Well, first, by “a set of procedures,” Buss is acknowledging that there may be many subsystems involved in delivering information from the environment to the mechanism. Visual systems, auditory systems, chains of logical inference, all of these may deliver information to the mechanism. Nevertheless, the mechanism is designed to take in only “a particular slice of information.” The mechanism for choosing mates, for example, will not process information regarding the color of the grass or the taste of the berries or the speed of passing clouds. Instead, that mechanism (it is alleged) is designed to take in and process only that information that is relevant to choosing a mate, and which information is relevant will depend on the operative “decision rules.” Such rules (we can imagine) amount to “If … then” clauses: if the mechanism registers so-and-so, then do thus-and-so and/or think so-and-so.8 Because these rules do not process information about innumerable other things (just as your house-key does not open innumerable locks), that mechanism is described as dedicated or domain-specific.

Finally, the presence of this mechanism – as opposed to some other mechanism – is explained by the fact that, given the preexisting materials of the hominid brain, this mechanism helped to solve an adaptive problem that confronted our hominid ancestors. This last part is extremely important. The psychological mechanisms that evolutionary psychologists claim fill the mind did not evolve to in response to problems we confront today. They may help in solving similar problems today, but that's not why we possess them. We possess them because they solved recurrent problems confronting our distant ancestors. And since they haven't been “selected out” of the population, current populations still posses them. As evolutionary psychologists like to say, our modern skulls house stone-age minds.

1.6 Some (More) Common Misunderstandings

As you might imagine, when the topic turns to human nature (and the alleged evolutionary roots of that nature), the landscape is suddenly awash in landmines. From the rather straightforward biological story above, it is easy to find oneself concluding all sorts of dubious things. I want to spend a few moments warning against several dangerous missteps: (1) conflating adaptation and adaptiveness; (2) conflating explanation and justification; (3) misunderstanding the scope of an evolutionary explanation; and (4) succumbing to the temptation of genetic determinism.

Conflating adaptation and adaptiveness

One of the most seductive confusions in this area concerns the distinction (and there is one) between adaptations and adaptiveness. Simply put, what is adaptive is not necessarily an adaptation, and adaptations are not necessarily adaptive. Some examples will help. Going to your doctor for an annual physical is adaptive insofar as it increases your chances of survival and reproduction; however, no one is going to conclude that the mind possesses a “going to the doctor” mechanism, dedicated to identifying doctors and motivating the organism to seek out their counsel. Going to the doctor is, if you will, a learned