GIVING DARWIN HIS DUE

Philip Kitcher

Columbia University

I

Twentieth-century attempts to evaluate the philosophical significance of Darwinism have been dominated by a pair of polar perspectives. At one extreme stand those who insist on the autonomy of philosophy and who conclude, with the early Wittgenstein that "Darwinís theory has no more to do with philosophy than any other hypothesis in natural science". At the other extreme are naturalists who maintain that "now that we know" this or that other fact about the cosmos, the human brain, or (most pertinently for present purposes) the role of natural selection in hominid evolution, traditional philosophical problems are easily solved. Each of the opponents lives off the excesses of the other. Both also overlook the possibility of a wide variety of ways in which scientific ideas, including Darwinís, might play a useful, but partial, role in philosophical discussion. It has proven remarkably difficult to give Darwin his due.

Philosophers drawn to the Wittgensteinian pole typically assume that there are concepts and methods whose application to philosophical questions is quite unaffected by the deliverances of any science, even a science that might transform ideas about life and mind. Their discussions of questions in metaphysics, epistemology, and ethics take over the idioms in which traditional philosophy has posed them, often without appreciating the fact that the language they employ was developed in response to a scientific picture that has long been superseded. This importation of older scientific presuppositions occurs even when the philosophical program aspires to revolutionize the discussion. Consider, for example, the group of philosophers most influenced by the younger Wittgenstein, the Vienna Circle. Their attempts to reformulate parts of classical epistemology as issues about the logical relations among statements took for granted a psychological picture that emerged in the early modern period. Far from freeing themselves from the psychological assumptions of Locke and Hume, the Logical Positivists and their Logical Empiricist successors simply buried those assumptions in their framing of problems about "basic sentences" and the "observational vocabulary".

No more plausible is the view that instant "scientization" of old philosophical problems will lead immediately to their solution or dissolution. In a famous passage, E.O. Wilson claimed that the time might have come for "ethics to be removed temporarily from the hands of the philosophers and biologicized". His subsequent discussions of the topic, with their inadequate response to the difficulties of deriving normative conclusions from factual premises, only showed that Wilson had not appreciated the depth and recalcitrance of the problems of moral philosophy. Philosophers have sometimes been tempted by similar grand visions of conquest in the name of their favorite science Ė particularly when the area to be conquered is the philosophy of mind and the science is some combination of fragments from the neurosciences, and, although their ventures are sometimes more sophisticated than Wilsonís, they fail for parallel reasons.

We should treasure whatever resources we have, wherever they come from. I want to resist both the anti-naturalism that celebrates the purity of philosophy and the hyper-naturalism that denies the possibility that genuine insights might be captured in language infected by outmoded science, thus ignoring the subtleties of the problems at which it flourishes its brave new findings. Philosophers should find it worthwhile to read Hume and Darwin, Kant and Einstein, Descartes and Chomsky. In what follows, I want to make a particular case for bringing Darwin on to the philosophical team, not as the star player who wins the day all by himself, but as a contributor to a much larger effort.

II

Darwinís significance for philosophy is clouded not only by the polarization that Iíve just sketched but also by the fact that there are at least three Darwinian doctrines that may be applied to philosophical questions. First is his insistence on the extent of variation within natural populations. Second is his claim that all living things are related by descent with modification and his use of this claim to explain a wide variety of biological phenomena. Third, and surely most well-known, is the thesis that "natural selection has been the main but not exclusive means of modification". As we shall see, much philosophical discussion has been provoked by this last idea, both by those who maintain that important aspects of our cognitive and emotional lives can be fathomed by viewing our minds as targets of natural selection, and by those who think that the theory of natural selection provides a model for building explanations in other, philosophical, domains.

Now these three doctrines inspire a range of philosophical investigations and conclusions, some of which seem to me far more well-grounded than others. The most visible ventures are those that make use of "Darwinís dangerous idea", the notion of natural selection, but we should not overlook projects that apply more basic Darwinian insights. Consider, for example, what Ernst Mayr has called Darwinís replacement of "typological thinking" by "population thinking". Darwinís recognition of a vast amount of intra-specific variation often goes unappreciated today in philosophical discussions, even though it has been uncontroversial for well over a century. Recent discussions of natural kinds, prompted by the seminal ideas of Saul Kripke and Hilary Putnam, often assume that one can revive essentialism. Yet if species are natural kinds no such revival is in prospect. Kripke and Putnam largely restricted their discussions to the cases of elements and compounds, and with good reason. For, given the insights of neo-Darwinism, itís clear that the search for some analogue of the microstructural essences canít be found. No genetic or karyotypic property will play for species the role that atomic number does for the elements.

Darwinís anti-essentialist message is important for other philosophical discussions, for example attempts to provide a value-free analysis of human nature or human functioning. Faced with the difficulty of understanding what makes human lives go well, some philosophers have been attracted to objectivist accounts of the human good: lives go well, they say, if the lives exemplify particular properties, independently of the subjectís desires or plans. Articulating an account of this type requires some way of motivating the specific choice of properties that is made, and itís at this point that essentialism offers inspiration. For one might take the properties to be exactly those that develop "the human essence". Neo-Aristotelian efforts founder, however, on Darwinís critique of essentialism. As we scrutinize the ways in which the moral theorizing proceeds, it becomes increasingly evident that some variants are being dismissed beyond the pale of humanity by the tacit invocation of value judgments. Biology wonít support the claims that these properties truly develop the human essence, and, in effect, the theory of the good simply recapitulates moral judgments that were made at the beginning.

Itís important not to overinterpret this debate, and to conclude that Darwinís undermining of essentialism refutes objectivism about the human good. What collapses is a particular strategy for articulating objectivism, one that responds directly to the reductionist challenge to provide a characterization of the objectively good in a language that refers only to biological properties (or to biological and psychological properties). If the objectivist denies that the reductivist challenge needs to be met, then the focus of debate shifts to complex questions in moral epistemology on which, at least prima facie, Darwinism has little to say. We see here, in miniature, a situation that often obtains in the relation between Darwinism and philosophical discussion: Darwinian considerations reveal that an option we might have taken to be available or a strategy that we might have pursued is closed off; philosophical debate is advanced, but not ended.

Iíve begun in this relatively small and apparently unexciting place because we ought to be aware of such partial successes as we attend to the ambitions of those who would build evolutionary epistemologies or found ethics on the deliverances of Darwinism. Too often, the views derived from Darwin are wild extrapolations from the core tenets of contemporary evolutionary theory. This is most evident when the philosophical project to be advanced requires a claim about the form of complex human capacities and the candidate claim rests on allegations about the history of natural selection in hominid evolution.

III

Since the controversy about human sociobiology, itís been evident that the attempt to attribute faculties, dispositions and forms of behavior is fraught with pitfalls. Serious theorizing about natural selection requires assumptions about the range of genetic variation, views about which phenotypic traits are genetically or developmentally tied together, understanding of the complexities of the environment, detailed investigations of the possibilities of building rival models, and, in the case of human beings and other primate species, recognition of the possible roles played by cultural transmission. In some subfields of sociobiology -- I think particularly of the study of insect behavior -- meticulous fieldwork and sophisticated mathematical modelling have gone hand-in-hand, yielding enhanced understanding. By contrast, in studies of human dispositions to behavior, grand conclusions have often been launched on the sketchiest evidence and have deployed qualitative arguments whose shortcomings were revealed at the first efforts in formalization.

Chastened by criticisms of early human sociobiology, many who are attracted to a Darwinian program of studying human behavior, whether they come to it from philosophy, from anthropology, or from psychology, have decided to change the name of the enterprise and to declare, very loudly, that they have acknowledged the errors of their predecessors. Yet recent literature in evolutionary psychology, some of which quickens philosophical pulses, has changed remarkably little. The fundamental strategy is to recognize the character of human psychological nature by exposing the ways in which particular "modules" have been individually fashioned by natural selection. So we are informed that there are modules for womenís being attracted to men with resources, for menís being attracted to women with a waist-hip ratio of around 0.7, and for both sexes to detect social cheats. Some of these conclusions have little bearing on philosophical discussions, others are taken to have import for epistemology and for ethics. I want to offer some brief reasons for skepticism about the ways in which this strategy has been undertaken so far.

The first point to note is that one can adopt Darwinism, including the claim about the importance of natural selection in evolutionary change, without endorsing any such particular conclusions about how selection has acted on our species. Thereís no forced choice between accepting the evolutionary psychologistís favorite collection of stories and reverting to Creationism. Second, one should note that the program of evolutionary psychology, with its commitment to human psychological nature, is at odds with the modest Darwinian theme of anti-essentialism Ė indeed, evolutionary psychology is dominated by a tendency to write as if frequency-dependent selection and polymorphism didnít exist. Third, the claims about the operation of natural selection may rest on more systematic evidence than those made in the heyday of human sociobiology, but they still share the old defects both of failing to develop careful mathematical models and of ignoring the possible impact of cultural transmission. Fourth, and to my mind most important, the conclusions typically presuppose guesswork both about the character of the (lightly-sketched) savannah environment and about the ways in which phenotypic traits are linked together.

Rather than venturing into the slough of evolutionary psychologyís depiction of human sexual relations, Iíll express my doubts by reference to the study thatís usually (and with justice) viewed as emblematic of evolutionary psychology, the hypothesis, advanced by Leda Cosmides and John Tooby, that human beings have evolved not to have a general-purpose logical faculty but a collection of specialized mechanisms, including one that detects violations of social rules. The essentials are as follows. Itís a familiar psychological result from the past three decades that undergraduates are often very bad at the Wason card-selection test, but that their performance is sensitive to the form of the problem they are asked to solve. Thus only about one fifth of the respondents, confronted with cards showing a circle, a square, a 3, and a 7, will recognize that they need to turn over exactly the square and the 7 cards to determine if the rule "If thereís a square on one side, thereís a 3 on the other" has been falsified; but, if the options are "drinking beer", "drinking soda", 25, and 16, most people see that you need to turn over the cards that show "drinking beer" and 16. Cosmides and Tooby hypothesize that the well-documented ability of subjects to do much better on the Wason test when it can be understood as a matter of detecting violations in social rules signals the existence of a special-purpose module that evolved under pressure to identify cheats in the ancestral savannah environment.

There are three reasons to be skeptical. First, the ability to identify cheating would appear to be favored by natural selection long before our ancestors, or their primate relatives, reached the stage of being able to formulate linguistic rules and wonder about their violation. As Iíll suggest below, the standard ways of conceiving the early scenarios of cooperation on the savannah (or in the forests) may be quite inadequate Ė our ignorance of the types of cooperation and of the details of the environments is, as Darwin would say "profound". But insofar as we have any grasp of the kinds of interactions that were important in the genesis of social relations among primates, it seems that it must have been important for animals to survey their conspecifics and judge whether others were continuing to participate in a joint venture. Speculatively, we can entertain the idea of an advantage obtained by those animals whose abilities to process or retain information were superior, and such differences might result from differences in genotypes expressed in the forms of neurotransmitters.

The speculation introduces my second point. Itís extraordinarily implausible to suppose that natural selection could have produced a device that just promoted the detection of social cheating. Evolutionary psychologists may not like to talk about genes, but, as soon as they start to discuss natural selection, they are up to their necks in genetic hypotheses. If there was natural selection for social-cheat-detection then there must have been genetic variation in some ancestral population that was either expressed at the phenotypic level only in the ability to detect cheats or else in that ability and in other characteristics whose selective importance is trivial by comparison. When we recall that genetic variation usually produces differences in proteins, we recognize that the entire story rests on the not-very-compelling idea that some protein difference is localized in one of the two ways just mentioned.

We might be inclined to swallow the genetic hypothesis and to disregard my first point about the evolution of social-cheat-detection on the grounds that Cosmides and Tooby have the best psychological explanation of the full range of Wason experiments. But this would be a mistake. Despite their considerable ingenuity in constructing variants on the Wasonian theme, Cosmides and Tooby fail to consider an important (but banal) rival hypothesis. That hypothesis claims that we have a general-purpose logical ability but that our logical reasoning works best on the types of problems with which weíre most familiar. At this point, those who have read Cosmides and Tooby are likely to protest, for the authors have spent a great deal of time and trouble in contrasting their own proposal with what they term the "familiarity hypothesis". But there are two importantly different versions of the familiarity hypothesis, only one of which has been addressed in the experiments that Cosmides and Tooby so painstakingly devise. A test may be familiar or unfamiliar because the subject is, or is not, at home with the content of the propositions in terms of which itís couched. Alternatively, a test may be familiar or unfamiliar because subjects have, or have not, done problems with that logical structure before. The version of the familiarity hypothesis which I propose focuses on this second type of familiarity. Pace Popper, the falsification of generalizations isnít something in which people much engage outside of academic disputes and one very special context, to wit our everyday checking of breaches of rules. Thus I propose that we have a generalized ability to do logic, that itís expressed in terms of our ability to solve problems with structures that recur frequently in our lives (or on which weíve been trained), and that the effects that Cosmides and Tooby see result from a commonplace fact that falsification problems only arise for many people in social contexts. Given the Darwinian difficulties of their preferred hypothesis, the balance of evidence should favor my suggestion, mundane and boring though it undoubtedly is.

I have gone into a little detail (although not enough to resolve all the complications of this case) because I want to contrast two strategies for generating Darwinian insights in philosophy. One, that I commend, remains close to the core doctrines of Darwinism, the three claims with which I began. The other, which needs to be undertaken with caution by enthusiasts and scrutinized closely by those to whom they announce their findings, attempts to advance specific claims about the ways in which natural selection has molded human propensities, and, on this basis, to resolve traditional philosophical problems. In principle, there is no bar to illuminating human behavior and psychological propensities by employing the perspective of natural selection, but itís important to recognize just how onerous are the demands of doing this in a responsible fashion. The temptations to rush down a Darwinian path to exciting conclusions about human nature that can revolutionize the social sciences and the humanities (including philosophy) are obvious: glitzy advertisements beckon the unwary. But those who want to tread this path should proceed more slowly. It already contains wreckage enough.

IV

So what can we glean from Darwin? In the next two sections, Iíll look at ways in which central tenets of Darwinism might offer insights for epistemology and for ethics. Letís start with the theory of knowledge, assuming that the Darwinian epistemologist avoids the trap (described in the last section) of trying to generate an account of our cognitive propensities from some fanciful adaptationist story.

Many philosophers have been inspired by the thought that human knowledge might satisfy abstract versions of the principles that govern the history of life. The idea can take a stronger or a weaker form. In the weaker version no more is supposed than the evolution of human knowledge Ė we are to think of knowledge as historical process and historical product, and invited to think of ways of characterizing the states of knowledge at various times, the kinds of transitions among such states, and the causal factors that promote or retard transitions of specific types. The stronger form, "evolutionary epistemology" as itís usually known, insists on a much closer analogy between Darwinís account of the history of life and the growth of knowledge either in the individual or in the species. Iíll consider two versions. On one of these, prominent in the writings of Donald Campbell, the individualís knowledge is conceived as something like a Darwinian process. Ideas are randomly generated and tested by experience. Those that are retained are those that survive the process of selection. A second approach, originally presented by Richard Dawkins, supposes that there are analogues of the entities whose transmission measures the course of evolution. Just as there are genes, and just as evolution is recorded in changes in the frequency of alleles, so too there are memes, and the growth of knowledge in the species is understood in terms of the spread of memes.

Insofar as either of these proposals is likely to illuminate epistemological questions, it will be because the theorist is able to understand those parts of the growth of knowledge that are either non-Darwinian or else fall outside the scope of the analogy. Consider first the use of evolutionary epistemology to understand an individualís cognitive accomplishments. We may concede that there are occasions in which novel concepts and propositions are randomly generated, and that there is a sense in which the testing of ideas is like a process of natural selection. Yet itís also pertinent to note that there are other procedures through which people develop new notions and theses. We reason from our prior beliefs, generalizing and using analogies (indeed, this is evident in the process of generating evolutionary epistemology itself!). Hence the process of generation isnít much like random mutation in the Darwinian story about life. Further, if the evolutionary epistemologist proposes that the processes to which Iíve alluded are analogues of recombination, we should point out that those processes donít consist in the swapping of bits and pieces of antecedent propositions. To make the analogy work, one would need a detailed account of just what the forms of the "recombination" are, and this is to desert the Darwinian framework entirely, and to engage, head-on, with all the serious epistemological problems of understanding methods of discovery.

Nor can we gain much insight into individual knowledge by likening the testing of ideas to a selection regime. To suppose that propositions augment their fitness when they occur in complexes that predict claims we discover to be true and lose fitness when they are found in clusters that generate expectations that are unsatisfied only substitutes a biological vocabulary for more familiar idioms in confirmation theory. The problems of understanding the gains and losses in "fitness" with any precision remain just as they were when we posed them in terms of confirmation and falsification. All that has been added is a misleading suggestion about the link between success in a regime of tests and the proliferation of "copies" or "descendants" of beliefs, which seems to make little sense within the context of individual epistemology.

Matters are somewhat better, I think, when we try to apply Darwinian ideas to problems in social epistemology. Although we should be cautious in supposing that the transmission of culture across the generations can be conceived in terms of "cultural atoms", analogues of the genes, there are instances in which the Dawkinsian notion of a meme is suggestive. Consider, for example, the spread of Christianity across the Roman Empire. Insofar as we can estimate the numbers of believers in major cities at various times in the first three centuries, the growth curve takes the sigmoidal shape familiar from population ecology. Conceivably, one could investigate this process from the perspective of evolutionary epidemiology, using the kinds of models that are available for studying the invasion of populations by pathogens. Although the work has not yet been done, success in this venture would obviously inspire efforts to find analogues of the parameters that appear in the models. We might thus discover something about the flexibility of Christian doctrine by comparison with its religious rivals by using analogies with mutation or with virulence.

In indicating possibilities of this kind, I emphatically donít want to claim more than that Darwinian thinking about the spread of ideas can offer us a perspective on historical processes that may or may not prove applicable to studies of change of belief. The ultimate test will be whether we can do justice to the phenomena in their full complexity. Darwin supplies us with some tools. Thereís no reason to insist, in advance, that they must be applicable or that they exhaust the arsenal we need.

My pragmatic opportunism about using Darwinian ideas in epistemology can be illustrated by a cluster of projects Iíve commended elsewhere. Scientific inquiry is a social phenomenon. Hence we should not simply focus on the ways in which individual beliefs are justified, but also inquire about the ways in which individual efforts are organized so as to promote the knowledge of the community. Given a particular type of epistemic predicament, we can consider which distribution(s) of group endeavors would yield the best chances of success and we can then investigate whether specified social institutions and individual motivations would lead the community towards or away from the optimum(a). To cite an example Iíve discussed in detail, if there are several methods for pursuing a particular inquiry then, under some circumstances, the best community policy is to explore more than one approach, even though one method would stand out as preferable if just one person were to be assigned the problem; moreover, it can be shown that motivations and social arrangements that might have seemed antithetical to the pursuit of truth bring the community quite close to the preferred division of labor. Problems of this type are similar in some respects to those arising in evolutionary ecology, and the mathematical formalisms developed there prove useful in the epistemological context. Thus the epistemologist can borrow tools forged by evolutionary biologists, but, as Iíve emphasized, this brings with it no commitment to a more global vision of the growth of knowledge as a Darwinian process.

The chief Darwinian moral for epistemology is, I think, connected with a more basic evolutionary theme. As numerous commentators have noted, Darwinís commitment to the idea of descent with modification resonates with the broad class of nineteenth century proposals to understand facets of the contemporary world as products of history. Historicism in epistemology doesnít need to rest on Darwinian grounds, but an evolutionary perspective offers a healthy antidote to the disease of synchronism that so often besets philosophical efforts to explain human knowledge. From Descartes to the present, generations of epistemologists have written as though the central problem is to uncover a structure of justification in an individualís beliefs that identifies special warranting relations only among the beliefs themselves or between particular beliefs and the individualís experiences. A far more realistic picture would identify the individual as part of a community, from which much is absorbed, most of it never to be seriously queried, and to view that community as one stage in a historical lineage. Perplexities about particular types of knowledge thus give way to attempts to understand how the pertinent propositions came to be incorporated within the set passed on by the tradition. Further, we can look to Darwin and to the theorists who have succeeded him for clues about how to represent the states of community knowledge at particular times and the transitions among them.

Consider, for example, our knowledge of mathematics. Epistemologists who are wedded to the project of synchronic reconstruction of an individualís beliefs have explored many possible sources for the ways in which our fundamental mathematical beliefs are justified (and, of course, they have differed in their choices about which are the fundamental beliefs). Appeals to knowledge grounded in grasp of concepts and to processes of intuition have been perennially popular. Given the well-known difficulties with both sorts of explanation, they appear as counsels of despair, especially when viewed from a Darwinian, or more generally, from a historicist perspective. Why not say the obvious things? Our knowledge of mathematics rests on the testimony of those who taught us. Collectively, mathematical knowledge evolves as successive communities of mathematicians respond to the mathematics they have inherited and to the problems bequeathed to them by natural scientists. The ultimate roots of the tradition lie in relatively primitive manipulations of the environment, carried out by our remote predecessors in India, Babylon, Egypt, and perhaps in sites of which we are ignorant. In the course of the subsequent history, mathematicians have been given a very special role, licensed to devise new languages that relate in ways they find interesting and illuminating to the corpus they have inherited. The demarcation of that role itself represents a discovery about community inquiry, to wit that it is good for other investigations that the role be filled.

Historicism, to repeat, is not specifically Darwinian. But Darwin provided one of the most successful and elaborate schemes of historical explanation, and is both inspiration and resource for historicist programs. Since epistemology can benefit from historicism it can learn from Darwin.

V

I turn, finally, to the area in which the significance of Darwinian ideas has been most hotly debated. Does Darwinism reveal how human societies ought to be constructed, or how human beings ought to behave? Does it finally debunk morality? Or is it simply irrelevant to our understanding of morality? Eminent scholars can be recruited in support of all the obvious responses. So what exactly is the relationship between evolutionary theory and ethics?

Letís start with a simple answer. There are many different projects of relating evolutionary biology to ethics, some of which are perfectly sensible, others that are flawed. The hyper-Darwinian ambition is to show how our understanding of the history of life yields new basic moral principles. Somewhat less ambitiously, one might contend that Darwinism supports some distinctive meta-ethical view, that it shows, for example, that moral judgments cannot have truth-values or that moral knowledge is impossible. Much more modestly, we can see the evolutionary understanding of our species as relevant to the tracing of all aspects of human history, including the history of our morality and social systems. Finally, one might suppose that recognition of the kinship of life, coupled with moral principles we already hold, enables us to arrive at new derivative moral judgments Ė perhaps we come to understand ourselves as having obligations not to treat other animals in particular ways. The simple answer proposes that the first two of these ventures are illegitimate, while the latter two are well-grounded.

This seems at least three-quarters right. Although proposals to derive substantive new ethical principles as corollaries of Darwinism sometimes acknowledge the familiar difficulty of inferring normative statements from factual statements, they are invariably vulnerable to the objection that Hume made over two centuries ago. Whether the would-be evolutionary ethicist adverts to (speculations about) "evolved human nature" or to "the fundamental character of life", itís always legitimate to ask whether we ought to acquiesce in the propensities attributed to us or to aspire to the ends that are singled out. On the other hand, the project of using what we know about hominid evolution to inform our account of the history of human morality (or of human societies) seems perfectly justified, and, in similar fashion, there is no bar against using empirical information, in conjunction with normative principles, to justify further normative claims. So the first, third and fourth parts of the response withstand scrutiny. What is more problematic Ė and more interesting Ė is the claim about the irrelevance of Darwin for meta-ethics.

Towards the end of Principia Ethica G.E. Moore declares that the only two things that are of fundamental value are personal relations and beautiful things. Skeptics might wonder how Moore could know that this is so, and their qualms wouldnít be assuaged by his murky references to "non-natural properties" and "intuitions". Mindful of the epistemological points made in the last section, we might recall that Mooreís judgment is the response of an exceptional thinker to very particular circumstances: Moore, brought up in late Victorian England, considers the nature of goodness from his rooms in a beautiful city, doubtless recalling his own experiences of friendship. Appeals to "intuition" are the last resort of those who deny the relevance of Mooreís personal history. We understand his judgment better if we see it as a reaction to the views he learned in childhood, tempered by his experiences and his reflections upon them. Like the creative mathematician, Moore extends and modifies the practice that his predecessors bequeathed to him, but, if we are to make clear the status of his moral judgments, we have to recognize both the rationale for his own amendments and the historical process that formed the backdrop to his own education. If Moore is justified, then we wonít find the justification in a synchronic reconstruction of his beliefs, but in a genealogy of morals that leads to him.

This example is intended to reveal that the connection between the second enterprise (Darwinian reforms in meta-ethics) and the third (tracing the history of our moral attitudes) is more intimate than we might have thought. We canít simply assume that a historical investigation will leave everything in place. For it might turn out that our reconstructed genealogy was difficult, even impossible, to square with the view that shifts in moral attitudes embodied discoveries. The details of the story might make us unable to see how successive transformations could be gains in moral knowledge.

In response to hyper-Darwinismís claim to draw normative moral conclusions from evolutionary premises, itís easy to swing to the Wittgensteinian pole and contend that the central questions of normative ethics and meta-ethics must be tackled in purely philosophical terms. Not only do those "purely philosophical terms" typically fail to acknowledge the importance of historicism in epistemology, but they also are laden with psychological assumptions that weíve inherited from the eighteenth century. Without denying the genuine insights of contemporary moral philosophy, itís possible to envisage that the idiom in which they are couched might need reform in light of better views about our psychological capacities, and that the result might enable us to adopt different positions from those that comprise the current menu of options.

The rest of this section will explore, speculatively, the possibilities at which Iíve gestured. Suppose we try to tell a story about the emergence of human morality. What might it look like?

Iíll begin from one of the most celebrated problems in the evolutionary study of behavior, the problem of altruism. Biologists, of course, take altruistic behavior to consist in activities that benefit another organism at cost to the agent, where both cost and benefit are measured in the Darwinian currency of reproduction. Models of kin selection and of reciprocal altruism, usually understood in the last twenty years in terms of evolutionary game theory applied to iterated Prisonerís Dilemma, have demonstrated possibilities for sustaining, and in some instances, originating altruism in this bare biological sense. Far more important to moral philosophy, however, is a richer conception of altruism that involves recognition of the needs of others and responses directed at fulfilling those needs. In previous work, both Elliott Sober and I have argued, on different grounds, that natural selection permits the evolution of this richer sort of altruism.

Unfortunately, as primatologists have provided richer descriptions of the behavior of our evolutionarily closest relatives, itís become evident that the models constructed to understand the evolution of psychological altruism are quite unrealistic. Chimpanzees and bonobos act very differently from the strategies that theorists attribute to altruists Ė in particular, they are frequently much less concerned to punish defections than they "ought" to be. I propose that our evolutionary theorizing about altruism has substituted mathematically tractable games for the complex many-agent interactions that are omnipresent in the social lives of higher primates. The central problem for a young social primate is to be accepted as part of a stable coalition, and there is good reason to believe that the selection pressure arising from this problem favors a blind and relatively non-punitive disposition to aid particular "friends". Natural selection, then may have fostered the development of capacities for sympathy.

Yet itís clear from studies of chimpanzee social behavior that those capacities are far from limitless. In situations where large evolutionary rewards are at stake, propensities to ally with another animal can be overridden by selfish aspirations. One possible view of chimpanzee (and bonobo) social life is that itís a battleground of conflicting tendencies, some of them altruistic (in the interesting psychological sense) and some of them self-interested. The conflict produces frequent ruptures in the social fabric, and the constant breaking-up makes way for constant making-up. Because the work of social repair is so costly and the sympathetic dispositions so limited, our evolutionary relatives can only manage societies of a limited size.

Extend these speculations one step further. Somewhere in hominid evolution we acquired the ability to live in larger social groups. How did we do it? One possibility is that, with the acquisition of language came also an ability to prescribe rules for ourselves and to obey them. Instead of the melée of competing tendencies that make chimpanzee/bonobo sociality so fragile, we evolved a rudimentary psychological faculty of normative guidance. Perhaps the primitive rules by which our ancestors governed themselves were the kinds of kinship regulations still recorded by anthropologists who visit the contemporary humans whose environments most resemble those of the distant past. Proto-morality might have begun from the injunction to act with the clan, and the evolutionary advantage of guiding behavior by proto-morality might have consisted in its yielding a more efficient taming of socially disruptive tendencies than that achieved by our evolutionary relatives.

How do we trace a route from proto-morality to Mooreís refined reflections? If anything is clear, itís surely that any such historical process would be largely subject to non-Darwinian forces. Cultural transmission and cultural selection will have been the prominent shapers of the modifications. The historical challenge of extending the story requires us to do justice to the great transformations that have obviously occurred in the construction of systems of moral rules, as our ancestors came to terms with other groups, fashioned societies in which individuals were assigned distinct roles, recognized the equal capacities of human beings with different phenotypes, and so forth. In outline, we can view morality as a human phenomenon that enters our history as a device for regulating the conflict between our sympathetic and selfish dispositions (where regulation plays a key role in the maintenance of our societies) and is further articulated through interactions among different social groups and membersí reflections on those interactions. What status this assigns to our moral claims depends, I suggest, on the details of the story, and the details require much more research in evolutionary biology, anthropology, psychology, and history than anyone has yet attempted. Nonetheless, it ought to be evident that this kind of history is potentially relevant to meta-ethical questions, and that we cannot neatly separate projects in the manner that my original simple answer proposed.

Everything I have said about the evolution and history of morality is admittedly conjectural. My sentences are peppered with Ďmightí and Ďpossibilityí, sometimes italicized, to draw attention to the fact that this is a story attending evidence. Any attempt to go further and to explore the intricacies of the history should be held to the same standards as those I proposed in section III, in the case of evolutionary psychology. As I pointed out there, using arguments about the action of natural selection to arrive at claims about psychological faculties and propensities, is always vulnerable to alternative explanations. Thus, even if the account I have sketched were elaborated more fully, it would be appropriate to begin from the claim that this is an explanation of how human morality might have evolved. Of course, the more phenomena that can be assembled within the purview of the explanation, the more constraints are generated for potential rivals Ė this, after all, was Darwinís argumentative achievement in the Origin.

Our current efforts to understand the content and justification of moral claims are, Iíve suggested, handicapped by failure to view those claims as products of a complex historical process and by the genuine possibility that the psychological vocabulary we bring to moral philosophy may need replacement. Whether we can work out a historical account that is more than speculation and whether evolutionary understandings can help reshape moral psychology are genuinely open questions. Positive answers cannot be reached by the kinds of shortcuts that have typified human sociobiology and the brand of evolutionary psychology to which it has given way. So I offer a modest conclusion: the connections between evolutionary theory and meta-ethics may be exposed by carrying out the program Iíve outlined or the evidence available to us may not allow discrimination of alternatives with very different meta-ethical implications. Darwinians need to blend optimism with caution.

VI

In a famous, and, to my mind, accurate, description of the discipline, Wilfrid Sellars proposed that "philosophy is the study of how things, in the broadest sense of the term, hang together, in the broadest sense of the term". Philosophers work in the interstices of other peopleís lines of business. Their task, and their opportunity, is to fit together pieces of the enormous fabric of human achievement. Because Darwinís account of the history of life is so large and important a part of that fabric, it must be relevant to philosophical ventures. Yet, for reasons at which Iíve gestured throughout this essay, there are major difficulties in applying Darwinian ideas in all the domains that excite his epigones. Moreover, as Iíve insisted, Darwinís great achievement doesnít make all other considerations and disciplines irrelevant, and, in particular, it shouldnít lead us to dismiss the potential insights of pre-Darwinian philosophizing. My recommendations for applying evolutionary ideas within philosophy are, I trust, obvious from my illustrative examples, and their prevailing character is one of cautious exploration. Darwin deserves his due, neither more nor less.