This is an excerpt from the Introduction to the book I am currently writing, Nature, Human Nature, and Human Difference. Comments welcome.
This book aims to do more than one thing. It is however, first and foremost, a work of historical ontology in Ian Hacking's sense. That is, it aims to show how kinds of thing, and kinds of person, that appear to be carved out within nature itself in fact come into being in the course of human history as a result of changes in the ways human beings conceptualize the world around them. In some of his most influential work, Hacking has taken the categorization of mental illness as an illustrative case study in the generation of historical kinds, or, as he sometimes calls them, 'transient'. Yet he emphasizes that transience is not the same thing as illusoriness, that at the very least it serves us well to take seriously and investigate the reasons why a culture generates new kinds from one era to another, and perhaps even, following upon our investigation, to retain them. Hacking's approach, which owes a deep debt to Michel Foucault's work on the history of sexuality and its focus on the construction in relatively recent history of the homosexual as a kind of person, is certainly fruitful far beyond the study of mental illness.
I am certainly not the first to suggest that the category of race --both the particular racial categories into which we divide the human species today, as well as the very idea that the human species can be so divided-- might appropriately be seen as a case of historical ontology. Yet there has been no sustained study of the intellectual history of the period in which the categories of race as we understand them took shape. In part, this absence can be explained by the reasonable perception that the most important factors in the shaping of these categories were not 'intellectual' at all, but economic, and indeed that it might even be offensive to think of the history that left us with the horrid legacy of slavery and systemic racism as having anything intellectual about it. Accordingly, excellent and abundant scholarship has been produced on the economic and social history of slavery. The things that people implicated in this history came to tell themselves and others about what kinds of people there are have been seen, also not unreasonably, as at best a posteriori rationalization or coming to terms with a world economic system that had taken shape not as a result of any innovations on the plane of ideas, but as a result of the sum total of practices out of which that economic system emerged.
This explanatory priority will not be disputed here, yet we will proceed with the conviction that there is always a complex interplay between what is said, what is believed, and what is done, and that at least part of the history of modern racism consists in accounting for the way in which early modern thinkers conceptualized and talked about race. That we are limiting ourselves to looking at thinkers here, and thus, it may be presumed, at people for whom the new categories of race were not particularly disadvantageous and who could therefore live a comfortable life of thought, distinguishes our focus not only from those who would say that economic history tells us the deepest story, but also from those who believe, again not unreasonably, that it is the muffled voices of those whom this new way of talking about kinds of people silenced and enchained that most need to be recovered by scholars today.
But La Peyrère, Leibniz, Linnaeus, and Blumenbach were not just mouthpieces of power; they were also heirs to a scientific and philosophical tradition that made it possible to say some things, and not others, about human nature and human difference, and what exactly they were able to say made a tremendous difference for the perception of the legitimacy of the racist institutions and practices that were sustained, in part, by ontological commitments to a basic difference between us and them. How and why European authors came to say just the things they did about race in the roughly 150 years from the middle of the 17th century to the end of the 18th, will be the focus of this study.
And it will not be enough to say that they said what they did because they were, with varying degrees of immediacy and explicitness, apologists for slavery. Apology for slavery can take many different forms; in early modern Europe, it often took the form of racial realism: the belief that the distinctions we make between races map onto pre-given racial kinds, conceptualized along biological lines on analogy to species. What we want to understand here is the full intellectual background that made this realism possible in general, and that also made the particular racial distinctions between, e.g., blacks and whites, possible. It is our hypothesis that a crucial feature of the emergence of the modern race concept was the collapse of a certain universalism about human nature, sustained by a belief in the transcendent essence of the human soul, and this belief's gradual but steady replacement over the course of the early modern period by a conception of human beings as natural beings, and thus as no less susceptible to classification in terms of a naturalistic taxonomy than any other natural being, plant or animal or mineral. The peculiarly modern ontologization of human difference, then, was made possible by the rejection of human nature, and the parallel insertion of humans into nature.
With Foucault, I share the view that kinds of person are in no small measure artefacts of social practices, that they are, to put it somewhat crudely, written into existence through administrative practices. At the most general level, we may conjecture that the individual human being is itself such an artefact, that what it is to be an individual human in the modern world is to be registered as such, in a church registry of baptisms or in a file in the department of vital statistics. On this view, the reason why you can drive right past a dead dog on the side of the road, whereas a dead human would require you to stop, call the police, and initiate a series of steps leading to the proper closing off of a life, is that in the case of the human, unlike the dog, there is paper work to be completed, the life cannot be closed off without a notation in the vital-statistical records. In this way, it is not that a being gets the status of a legal being in recognition of its prior status as a moral being, but rather it is precisely the other way around: beings come to have a certain moral charge to them --they may not be arbitrarily killed, and if they are dead their corpses must be treated according to a set of rules, for example-- because they are classified as legal individuals.
Of course, the interplay between these two is complex, and I am emphasizing the priority of the legal over the moral for the sake of argument. In the abortion debate, opponents of abortion have a prior commitment to the moral status of fetuses, and so seek to win a legal status for these entities that would reflect the moral one. But it is quite likely, given the evidence from similar cases, that if fetuses did have a long-established legal status, many who do not in our own culture believe that abortion is a moral issue would think differently. We already do think very differently about our moral commitments to different classes of animals (pests, livestock, vermin, wildlife, zoo animals, to name a few), where clearly the only basis for distinction is a legal or social one, stemming from the position they occupy in human society, and has nothing at all to do with differences in their internal capacities, their neurophysiology, or the like.
The connection to the problem of race should be obvious: kinds of person are to no small extent administered into being, so to speak, brought into existence through record-keeping, census-taking, and, yes, bills of sale. A census form asks whether a citizen is 'white', and the possibility of answering this question affirmatively helps to bring into being a sub-kind of the human species that is by no means simply there and given, ready to be picked out, prior to the emergence of social practices such as the census. Censuses, in part, bring white people into existence, but once they are in existence they easily come to appear as if they had been there all along. This is in part what Hacking means by 'looping': human kinds, in contrast with properly natural kinds such as helium or water, come to be what they are in large part as a result of the human act of identifying them as this or that. Two millennia ago no one thought of themselves as neurotic, or ADD, or straight, or white, and nothing has changed in human biology in the meantime to explain how these categories could have come into being on their own. This is not to say that no one is neurotic, straight, white, etc., but only that how they got to be that way cannot be accounted for in the same way as, say, how birds evolved the ability to fly, or how iron oxidizes.
In some cases, such as the diagnosis of mental illness, kinds of people are looped into existence out of a desire, successful or not, to help them. Racial categories seem to have been looped into existence, by contrast, for the facilitation of the systematic exploitation of certain groups of people by others. Again, the categories are able to facilitate the exploitation in large part because of the way moral status flows from legal status. Why can the one man be enslaved, and the other not? Because the one belongs to the natural-seeming kind of people that is suitable for enslavement. But again, categories cannot be made to stick on the slightest whim of their would-be coiner. They have to build upon habits of thinking that are already in place. And this is where the history of natural science becomes crucial for understanding the history of modern racial thinking, for the latter built directly upon innovations in the former. Modern racial thinking could not have taken the form it did if it had not been able to piggy-back, so to speak, on conceptual innovations in the way science was beginning to approach the diversity of the natural world, and in particular of the living world.
This much ought to be obvious: racial thinking could not have been biologized if there were no emerging science of biology. I would like to dwell on this obvious point, however, and see what more unexpected insights might be drawn out of it. What might not be so obvious, or what seems to be ever in need of renewed pointing out, is a point that ought to be of importance for our understanding of the differing, yet ideally parallel, scope and aims of the natural and social sciences: the emergence of racial categories, of categories of kinds of human, may be best understood as an overextension of the project of biological classification which was proving so successful in the same period. We might go further, and suspect that all of the subsequent kinds of person that would emerge over the course of the 19th and 20th centuries, the kinds of central interest to Foucault and Hacking, amount to a further reaching still, an unprecedented, peculiarly modern ambition to make sense of the slightest variations within the human species as if these were themselves species differentia. Things were not always this way. In fact, they were not yet this way throughout much of the early part of the period we call 'modern'.
 See Ian Hacking, Historical Ontology, Cambridge, MA: Harvard Unversity Press, 2002.
 See Ian Hacking, Mad Travelers: Reflections on the Reality of Transient Mental Illness, Charlottesville: University Press of Virginia, 1998.
 See Michel Foucault, Histoire de la sexualité, vols. 1-3, Paris: Gallimard, 1976-84.
 Obviously, we can barely begin to summarize this vast literature here, but a few representative works include Ira Berlin, Many Thousands Gone: The First Two Centuries of Slavery in North America, Cambridge, MA: Harvard University Press, 1998; David Brion Davis, Inhuman Bondage: The Rise and Fall of Slavery in the New World, Oxford University Press, 2006; Patrick Manning (ed.), Slave Trades, 1500-1800: Globalization of Forced Labour, Brookfield, VT: Variorum, 1996.