Download Human nature Milan revised Jan 2015

Pluralism and Process in Understanding Human Nature1
John Dupré
The Centre for the Study of the Life Sciences (Egenis)
University of Exeter
Introduction
Human nature is one of the most controversial topics in intellectual life. There
is disagreement about what the concept means, whether any such thing
exists and, if it does, what are its particular characteristics. These questions
took an extreme form in the last decades of the twentieth century with the
emergence on the one hand of sociobiology (Wilson 1975), a rather crude
reduction of human nature to evolutionary biology on, and an influential school
of cultural anthropology, which seemed to see humans as almost indefinitely
variable and malleable, on the other (e.g. Geertz 1973). The latter view, to
which my position in this paper will be closer, is often interpreted as holding
that any attempt to describe human nature was misguided. However I do not
want to deny the relevance of biology to understanding the human. On the
contrary, my argument will be that it is our distinctive biology—though
distinctive in degree rather than anomalous in kind—that is the key to
understanding the remarkable flexibility, or plasticity, that is at the heart of
human nature.
This debate has been especially heated as it has widely been seen as closely
connected with deep political differences. Critics of biological human nature
have often accused its defenders of lending support to political conservatism:
the immovable realities of human nature would inevitably undermine attempts
radically to ameliorate the human condition. No doubt some supporters of
sociobiology and similar positions were politically conservative. On the other
hand some were certainly not and had good political reasons for their stance.
The research leading to this paper has received funding from the European
Research Council under the European Union's Seventh Framework Programme
(FP7/2007-2013) / ERC grant agreement n° 324186.
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Noam Chomsky, famous both for his claim that language was an innate
feature of human nature and for his radical political views, has written: “The
principle that human nature, in its psychological aspects, is nothing more than
a product of history and given social relations removes all barriers to coercion
and manipulation by the powerful” (Chomsky 1975). I will not discuss these
important debates here. I mention them only as a reminder that while the topic
of human nature is intellectually challenging and fascinating, there is more at
stake than just getting things right.
The dismissal of human nature is surely historically anomalous. Most thinkers
have held that human nature was an essential and even neglected topic for
study. Thus David Hume: “Human Nature is the only science of man; and yet
has been hitherto the most neglected” (Hume 1888, p. 273). Thinkers as
influential as Darwin, Freud and Marx have offered views about human nature
and more recently it has been a topic for some practitioners of many scientific
disciplines—psychology, neurology, physical anthropology, etc.—and, most
notoriously, as mentioned, sociobiology and its successor, evolutionary
psychology. These last, in particular, have agreed with Hume that ‘human
nature is the only science of man’ and adding this to the view that science is
the only source of knowledge, have taken their conception of human science
to be the key to all aspects of human behavior, from competition and
reproduction to art, religion and philosophy.
There are many more specific, if less scientifically grounded views on the
topic. Rather uncontroversially, according to the ancient Chinese philosopher
Xun Zi “it is human nature to want to eat to ones fill when hungry, to want to
warm up when cold, to want to rest when tired” (Ebrey 1993, p. 26); and more
controversially, “Human nature is such that people are born with a love of
profit” (Ebrey, loc. cit.)—though unlike many contemporary subscribers to a
similar view, Xun Zi took this to illustrate that human nature was a bad thing.
Perhaps this remark better reflects the way that references to human nature
are used in everyday speech as an argumentative trope, a framework for
generalisations that claim insight into, or just exercise wit about, the human
condition. The Roman playwright Publius Terentius Afer, for example, is said
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to have opined that “Human nature is so constituted, that all see and judge
better in the affairs of other men than in their own”—a thought in which most
of us will see a grain of truth.
As a starting point for the present discussion, I shall understand ‘human
nature’ as noncommittally as possible, to mean whatever is empirically true
about humans. Such truths could be universal or culturally local. Surely
Hume is right that we would like to know as well as possible what we are like.
But if, as for example was famously argued by the existentialists, what we are
like depends in crucial ways on our choices and decisions, then that is
something that belongs in a proper account of human nature.
What Human Nature Is Not
Like all species humans are variable. Variability, as Darwin has taught us, is
what makes evolution possible. Without it, we would not exist. A human
essence, a property necessary and sufficient for anything to be human, is not
something we should expect to find. This simple point, though important,
doesn’t get us very far. It is not of the essence of an elephant to have a trunk:
if some freak elephant were born with a snub nose we should not exclude it
form the species from which it arose. Still, all or almost all elephants do have
trunks, and this is certainly something we should include in an empirical
account of elephant nature of the broad kind in which I am interested. It is
important that we recognize that biological generalizations will always admit of
exceptions, but this hardly makes generalization impossible.
Debates about human nature, anyhow, are generally concerned with human
psychology and behavior rather than physiology, and here the key idea is not
so much variability as plasticity, of which variability is of course a product.
This, I think, is what is most fundamentally lacking in the projects of
sociobiology and evolutionary psychology2. The latter, in particular, supposes
Here I mean specifically the project associated with authors such as Leda
Cosmides, John Tooby and David Buss. Sometimes this project is referred to
capitalized, as Evolutionary Psychology, to distinguish it from a range of other
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that the human mind is composed of discrete modules, evolved during the
Pleistocene, or late Stone Age, to solve specific problems posed by human
life during that period. Of course evolutionary psychologists acknowledge
some variability. There is the normal variability of the kind illustrated by the
snub-nosed elephant: some people have abnormal modules. And more
importantly, there is variability that comes from the interaction of modules with
a variable environment. All or almost humans might have, say, a statusseeking module. But seeking status in a hunter-gatherer society in New
Guinea no doubt calls for different behavior than it might for a fashion
consultant in Milan.
So evolutionary psychology allows for some variability in actual behavior, but
the behavior is supposed to emerge from a broadly universal human mind,
indeed essentially the same mind as might have been found in our Stone Age
ancestors. This collection of mental modules is the universal human nature
they assert, and it is a nature grounded on genetic determinism. Not, of
course, the genetic determinism that sees people mindlessly emitting
behavior as their genes give orders, but the determination by genes of the
system that processes inputs from the environment and emits behavior in
response. Like so much reductionist interpretation of evolution, the fatal flaw
of this scheme is that it ignores, or black-boxes, development. In fact,
however, the interaction of the environment with the mind does not begin after
genes have somehow formed a standard and universal human mind; the
environment interacts with the genes (and more) throughout the process of
human development. So a different environment does not just produce
different behavior in response to that environment; different environments
produce different minds.
The co-production of the organism by biology and environment is not
something unique to the human mind of course, but is everywhere in the living
world. The appearance of developmental homogeneity is as much a
investigations of the historical trajectory leading to current human psychology.
A standard reference for Evolutionary Psychology is Barkow, Cosmides and
Tooby (1992).
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consequence of the uniform circumstances in which organisms of a particular
kind develop as it is of their identical or similar genomes. And part of the
reason that organisms develop in homogeneous environments is that they
often work hard to construct appropriate environments, a point that has been
developed in recent elaborations of the idea of niche construction (OdlingSmee, Laland, and Feldman 2003). Birds don’t just happen to grow up in
nests, for instance; these are painstakingly constructed by their parents.
Looking beyond this appearance of developmental uniformity, we actually find
an enormous amount of developmental plasticity, a phenomenon that has
been documented in encyclopedic detail by Mary Jane West Eberhard (2003).
This plasticity applies to physiology as much as to psychology. Famous
illustrations of this are provided by quadrupedal animals that have had to
learn to be bipedal. Where this has been from a congenital abnormality, as in
the most famous case of a goat born without forelimbs and studied by the
Dutch morphologist E. J. Slijper, the developmental accommodation to this
disadvantage can be remarkable. This animal learned to walk quite
comfortably on its hind legs and on post mortem examination was found to
have radical changes in the anatomy of its legs and hips that accommodated
these changes (West Eberhard 2003, pp. 51-2). Development is a highly
integrated process, and changes to some aspect of it will often induce a range
of compensatory changes in other features.
That such plasticity applies to psychological development should hardly be
surprising. Indeed, if there were no such plasticity the concept of learning
would make no sense. It is, of course, possible that learning, or more
generally the response of psychological development to environmental
contingencies, could provide only a superficial filling in of details within a
genetically determined framework. The physiological examples are intended
at least to weaken the intuitions that favour such an understanding. In what
follows I hope to offer a more positive account that provides further motivation
for adopting a more radical view of psychological developmental plasticity.
The central claim is this: the achievement of human evolution over the last
few million years has not been the acquisition of a wider range of specialized
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abilities to deal with specific problems, but rather the developmental flexibility
to acquire a wide range of extremely complex behavioral repertoires.
Humans as Processes
In the previous section I have several times emphasized the importance of
development in understanding human nature. Much of the tradition of
discussing this topic has seemed to focus on the distinctive properties of an
adult human in the so-called prime of life. In the past this adult was generally
assumed to be male; now evolutionary psychologists spend a lot of time
describing the differences between the nature of adult men and women. But
as the developmental psychologist Alison Gopnik (2010) has remarked, “One
of the best ways of understanding human nature is to study children. After all,
if we want to understand who we are, we should find out how we got to be
that way.” Children, surely, have just as much right to claim a human nature
as their parents. In fact studying children has a particular advantage:
differences in what happens to children can help us to explain the differences
between adults.
Humans, as we all know, go through a characteristic series of life stages:
fetus, infant, child, adolescent, adult. These are not, of course, a series of
discrete steady states separated by metamorphosis, as one might describe
the life cycle of a butterfly—egg, caterpillar, chrysalis, butterfly—but rather a
smooth progression from which these named stages are abstractions.
Adhulthood, for instance, encompasses a gradual progression from youth to
old age. The whole sequence amounts to the human life cycle. A central
philosophical problem for centuries has been explaining our intuition that the
stages of the life cycle constitute some single continuing entity, a person.
Philosophers have divided over whether the identity of a person depends on
persistent psychological features, notably memory, or whether the identity of a
person is the same as the identity of a material thing, a human animal.
Intuitions on the question are typically tested with thought experiments such
as John Locke’s cobbler and prince who exchange minds, or more recently
with imagined brain transplants. Is the prince the cobbler’s body with the
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mind of a prince or the prince’s body with the mind of the cobbler? Intuitions
tend to favour the former and, reflecting the widespread transition from
Cartesian mind/body dualism to a largely similar brain/body dualism, some
philosophers even make the bizarre claim that a person is identical to their
brain.
It is, at any rate, easy to see the problem. In what sense could a fetus be the
same thing as an old man 80 years in the future? They are unlikely to have
any matter in common, and their properties are quite different, both physically
and psychologically. Even young people don’t remember being fetuses, and
some old people, sadly, don’t remember anything. A natural thought here,
much discussed in the literature, is that we should appeal to spatio-temporal
continuity. But though there is surely something in this, it is clearly not
enough. To take another ancient philosophical example, a block of stone is
not the same thing as a statue, even though the two are spatio-temporally
continuous. Or at any rate it is not the same statue, because the original
block of stone isn’t a statue at all. This draws attention to the logical point that
the kind of identity question in which we are interested is a question relative to
a kind. The old man certainly isn’t the same baby as the baby he once was:
spatio-temporal continuants can come to be or cease to be kinds of things.
So to what kind do the fetus, the child and the old man all belong? The kind
that motivates much of this philosophical debate is that of a person, but for my
present purposes there is a more straightforward answer, that they are all part
of a human life cycle. But, to get finally to the point, a life cycle is not a thing
but a process. Of course we could insist on saying that they are all human,
but this just restates the problem. How can all these very different entities be
the same kind of thing? And the answer is that they are not; they are all parts
of the same process. Humans are processes not things.
Perhaps this still only names the problem. What is this distinction between a
process and a thing? And what is it for a process (or for that matter a thing) to
persist through time? I shall be very brief with the first question, though it is
an ancient one, dating back to the pre-Socratic Greek philosophers. My very
simplified answer is that a process is something to which change is essential.
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For an ontology of things, change is a problem: what changes can a thing
undergo and still remain the same thing? Answering this question has been
one motivation for essentialism, the idea that there must be some essential
property or properties that makes the thing what it is and the continued
possession of which underlies its persistence through change. Processes, on
the other hand, must change to continue to exist. For a river, a storm, a
battle, cessation of activity is cessation of existence. It is the characteristic
activity—flowing, blowing, or fighting—that constitutes the existence of these
processes. This, I think, is the ontological category under which we should
think of living beings in general and ourselves in particular.
Let me turn in more detail to the second question, how do either things or
processes persist through time? There has been a good deal of philosophical
discussion in recent years about what constitutes the persistence through
time of a thing. A major divide is between so-called endurantists and
perdurantists (see Noonan and Curtis 2014). Perdurantists hold that things,
often described in this context as “space-time worms”, exist in four
dimensions and have temporal parts just as they have spatial parts.
Endurantists object that, contrary to this view, when we encounter a thing we
encounter it all, not just a small part of it. Sometimes the latter view is
combined with presentism, the thesis that only the present really exists at all.
With or without this corollary, it is evident that the endurantist will need to
address a version of the problem I have been discussing, how, say, a fully
present baby at one time can be the same entity as a fully present
octogenarian eighty years later. The perdurantist, has an immediate answer
to this question: they are temporal parts of the same four-dimensional thing,
or ‘space-time worm’. The problem that most interests me from this
perspective is a rather different one, to which I shall turn briefly below: how do
we distinguish particular space-time worms from the tangle of interconnected
entities that make up the biosphere.
Without going much further into these deep ontological divisions, I would like
to suggest that the whole issue looks much more intuitively tractable from the
processual perspective I advocate. Everyone agrees that a process is
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composed of temporal parts, and if one thinks of a human as most
fundamentally a life cycle, surely a process, it is obvious that one should not
expect, when confronted with a part of it, say an adult, also to be in the
presence of its earlier (or later) temporal stages (for an explicit application of
this perspective to the question of personal identity, see Dupré 2014). This
observation leaves open the major question of what relations between stages
of a process constitute these stages as parts of the same process, a problem
exacerbated by the difficulty just mentioned of distinguishing a living process
from multiple other such processes with which they are typically intricately
entangled at various points in its history. But the core of an answer is
reasonably clear nonetheless: the temporal parts of a process are connected
by causation. The state of a battle, a storm, or a river at one time is caused
by its state at a previous time (in interaction with other external causes). And
the same goes for an organism. The organism is a sequence of such causally
connected states.
I should note in passing that I do not wish to subscribe to the standard version
of four-dimensionalism. The dichotomy I have just considered contrasts views
that give a special status to the present with those that treat all times
symmetrically. My own view is that the proper dichotomy is between the past
and the future: the past and present exist and the future doesn’t. The present
has a special status as dividing the fixed past from the still unformed future.
This is sometimes called the ‘growing block’ view of ontology: things grow as
they move into the future and make real more of the past. This seems a view
very well-suited to an ontology of processes, and has particular relevance to
organic processes, notably human ones, as making room for the possibility of
agency and even free will in the construction of the future. But this is not a
topic I can pursue in any detail here (but see Dupré 2001, ch. 7; 2013).
I have mentioned the problem of distinguishing a living process from the living
context in which it is embedded. Actually I take it to be a major advantage of
a processual perspective, that it not only recognizes this problem, but is also
able to acknowledge that the division of biological reality into distinct
processes is not always an unambiguous or even objective matter. Most of
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life is more or less symbiotic, and the degree of integration between symbiotic
partners is highly variable. We are generally comfortable with considering
mitochondria, entities in cells that provide energy for the cell’s chemical
reactions, as part of the organism, even though they have a distinct origin (in
an ancestral bacterium) and reproduce independently. Their processes are
entirely embedded within those of the organism in which they live. We are
less sure about the trillions of symbiotic bacteria—90% of the cells that make
up a human body, in fact—that line our gut and cover the surfaces of our
skins, though many of these are also essential for our proper functioning. It is
not clear that there is any fact of the matter as to whether these, or some of
these, should be considered to lie within or without the boundaries of the
human organism. And the process perspective may even weaken the hold on
us of the individualism that has been such a dominant theme in modern
Western thought, by reminding us that we are highly social organisms, and
therefore parts of many social processes.
But I will not suggest here that there is any problem in the intuitive assumption
that individual humans are importantly separate, or at least conceptually
separable, processes too. From a biological perspective what provides the
coherence of such processes are, first a huge range of metabolic activities
that maintain a complex organization in energetic disequilibrium with its
environment and, more importantly for present concerns, a developmental
process that carries a human through the various stages of a human life
cycle. While it is certainly true that this developmental process follows a
highly predictable sequence of stages (fetus, child, adolescent, adult, etc.),
there are many aspects of this process that are highly variable. One reason
for this is that far from being an internally closed causal process, development
is equally driven by external influences.
As I mentioned earlier, the appearance of human homogeneity is the result of
shared environments as well as of similar biological processes. But as we
extend our vision in both time and space environments change, and human
diversity becomes more evident. Spatially we see the cultural diversity that
has been documented extensively by anthropologists, a discipline one wing of
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which has consistently repudiated on empirical grounds the human universals
alleged by sociobiologists and their like. Temporally we see evolutionary
processes at vastly higher rates than are possible from the perspective of
genetic evolution still assumed by some to be the only possible basis for
significant evolutionary change. The life of the Pleistocene hunter-gatherers
so important to the ideas of evolutionary psychologists was very different from
that of a contemporary city-dweller. Caves, wood fires, and dangerous beasts
to be fled or eaten provided a very different context for the human
developmental process than do city apartments, hospitals and schools. It is
not surprising that the developmental process should take very different
courses in such wholly different contexts, not least with respect to the
development of the mind.
A living developmental process is (more or less) adapted to the conditions in
which it exists. Whether or not we want to say, as some do, that survival and
reproduction are the ultimate purposes of a developmental process, we
should be Darwinist enough to acknowledge that the developmental
processes we find today are likely to be those that tend to lead to these
outcomes. Organisms are very complex entities, and it is an amazing
achievement to be a developmental process that leads reliably to survival and
reproduction. It is a natural thought that the process should be very tightly
constrained to produce outcomes that have a fair chance of meeting these
desiderata. On the other hand a tightly constrained process will lead to a
highly predictable outcome and one that is adapted to a very specific
environment. As the environment changes the adaptedness generated by
such a process will cease to be effective. Orthodox Darwinists respond to this
problem by hypothesizing random changes in one determinant of the process,
the genome, such that some of these changes will produce variations that
adapt their lucky bearers to the changed conditions.
I won’t try here to evaluate in any detail the general plausibility of this latter
picture (for more detailed discussion, see Dupré 2012, ch. 9). I do want to
insist, though, that it is not the only way in which organisms adapt to their
environments. As already noted, another is through developmental processes
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that can respond to the environment in ways that produce developmental
trajectories that are more specifically suited to the outcomes they encounter.
Such developmental flexibility abounds throughout the living world. To cite
one important example, many plants change their shapes in highly plastic
ways to accommodate to the availability of light, or their size to respond to the
availability of nutrients. Clearly under appropriately varied conditions this is a
better strategy than having a predetermined size and shape. It is sometimes
objected that such a change cannot count as evolutionary because no
difference is transmitted to the underlying cause of the change, the genome.
But this is plainly question-begging, simply defining evolutionary change as
genetic. Suppose for some reason the nutrient supply for a species of plant is
permanently degraded. The plants grow smaller. As long as that change
persists they will continue to be smaller. It is also possible that they become
smaller through a selection of genetic causes of reduced size. Either way the
species responds adaptively to the change. Why call one kind of change but
not the other evolutionary? This is pure prejudice. In fact the only reason why
the first scenario might be denied the status of evolutionary change is that it
leaves the species able to revert to its ancestral state in case of a reversal of
the environmental change, a blatantly question-begging insistence that
evolution is opposed to flexibility.
And this brings us back to the human. Humans have arguably pursued the
strategy of adaptive plasticity to the greatest extent of any organism. Not only
do humans have the ability to learn to live in a great variety of different
environments both cultural and natural—from Inuit hunters in the frozen North
to tropical city dwellers in Singapore or Rio de Janeiro; they have also evolved
the ability to construct the environments in which they live. This is, like other
extraordinary human capacities, not unique in kind to humans. One of the
major insights in recent evolutionary thinking is that all organisms act on their
environments rather than as, in traditional evolutionary thinking, merely
adapting to it (Odling-Smee, Laland, and Feldman 2003). Classic examples
are the dam building of beavers and, as explained in great detail by no less an
evolutionist than Charles Darwin, the ability of the humble earthworm to
transform the soil environment, and to do so in respects that suit its way of life
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(Darwin 1881). But these are no more than striking examples, and all
organisms have some effect on their environment; and thus their evolution is
a dialectical interaction between them and the world in which they live.
Once we recognize that a plastic phenotype and the ability of the organism to
change the environment in which it develops provide a possible basis for
evolutionary change, we see that just such a process permeates human
evolution. Providing ourselves with heated homes and food-laden
supermarkets has radically changed the conditions under which contemporary
humans survive (and reproduce). It may well be that genetic evolution will
eventually track these changes, making us more suited to heated buildings
and less well adapted to the vagaries of the outside climate. But whether or
not this happens, there is no reason not to count our development in a quite
novel environment, and our plastic responses to this both physically and
psychologically, as evolutionary changes.
Technological innovation is, in this broader sense, a major driver of human
evolution. Left to nothing but our biological endowment we are fairly slow and
cumbersome creatures. With cars, trains, and planes, we are the fastest
beasts on the planet. I have argued that generations growing up with mobile
phones are developing a profoundly new conception of social space, one that
is no longer fundamentally spatial. The fact that one’s circle of friends travels
everywhere with one in cyberspace, often in continuous conversation,
reduces the salience of physical proximity, a fact that notoriously provokes
mutual incomprehension and even hostility (in Britain, at least) between
people of different generations sharing train compartments.
People, then, are developmental processes shaped by a variety of factors
both internal and external. I shall summarize where this leaves the question of
human nature at the end of this talk. But first I want to draw some
connections with a different but related topic, pluralism.
Pluralism in Understanding Human Nature
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At the beginning of this talk I highlighted the polarized positions that dominate
the discussion of human nature. A fascinating feature of the debate is that
while almost everyone officially endorses a modest pluralism of causes, the
view that human behavior must be explained in part by (more or less)
universal features of human biology, in part by social forces, and in part by the
idiosyncrasies of individual choice, both sides accuse the other of
uncompromising reductionism, either to social influences or to a human
nature grounded in the brain or the genes. And indeed, reading the works on
either side of this debate it is easy to understand these accusations: having
paid lip service to pluralism, most authors go on to wax lyrical about how
much more significant and useful is their own preferred perspective. A slightly
cynical explanation of this tendency is that is easier, or at least more attractive
to the reader, to provide a theory that explains (almost) everything than to
explore its limits.
At any rate, this last remark locates one of my aims in this paper: to provide a
discussion of human nature that acknowledge the multiplicity of causes,
biological, social, and individual, that interact to produce human behavior.
Methodologically, I advocate the necessity of a pluralism parallel with the
pluralism of causes just mentioned. No single scientific approach can provide
a complete understanding of human behavior. This should be clear enough
simply from reflection on how science works in addressing highly complex
phenomena, through abstraction. Most scientific models focus on a relatively
small range of factors that are taken to be the most important in explaining a
particular class of phenomena. The processual perspective that I have been
describing adds a twist to this observation. Theories of human behavior
generally not only focus on a particular set of causes, but they present a
model of objects with a particular set of properties and dispositions. They
thus involve both an abstraction from the full complexity of the causal nexus in
which humans live, and a temporal abstraction from the extended process
that constitutes the full human life cycle.
There is nothing wrong in principle, for instance, with treating humans as
consumers optimizing their utility in the face of a set of prices and a budget
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constraint. It might turn out that for some economic models other factors
affecting aggregate economic behavior come close enough to cancelling out
to make such models effective and useful. For analyzing the market in pork
bellies this is quite plausible; for predicting GDP probably less so. But
however successful or unsuccessful such models may turn out to be
empirically, no one really believes that humans are nothing but utility
maximizing machines, though some people do seem to come alarmingly close
to doing so.
This kind of abstraction (or idealization—this important distinction can be
ignored for present purposes; for discussion, see Thomson-Jones 2005)
raises a well-documented dilemma between utility and realism. A relatively
simple model may provide real insight into one important aspect of a situation
far too complex to comprehend in all its gory details; but it may fall a long way
short of providing an accurate fit with the complexity from which it abstracts.
Bringing in further relevant factors should be expected to close this gap, but
all the time reducing the insight into the real world dynamics. When maximum
realism is important, for example in trying to understand and predict the
dynamics of climate change, models are constructed of a complexity that no
one can fully understand, and this no doubt contributes to the ease with which
skepticism about their legitimacy can be promoted.
In the case of humans, in certain respects far more complex entities even
than the world’s climate system, we are interested in many perspectives on
their existence and behavior, and sometimes very simple models can help us
to understand aspects of these. The tragedy of the commons, for example, to
return to the domain of economics, provides a simple and persuasive
explanation of why, at a certain point in the development of human resources
we will need a sophisticated and enforceable international fisheries policy. No
boat, or fishing nation, has any motivation to reduce its catch given that other
boats or nations are not expected to do so; and given an agreement, each
nation is motivated to break it if they can get away with it. This does not tell
us that some countries may not impose their own, altruistic controls on fishing,
though it may suggest that these are unlikely to do much good. It certainly
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doesn’t tell us how fish fit into the dietary or cultural beliefs of different nations,
or which fish they prefer to eat, though these might in fact have a major
bearing on the rate of collapse of fish stocks. But if we are interested in, for
instance, how the collapse of fisheries will affect the lives of different peoples,
these latter are just the kinds of things we will need to understand.
The importance of partial perspectives on complex phenomena, provided by
different models or theories that abstract from much of the less relevant detail
of the phenomena is well understood in the philosophy of science. I have
elsewhere argued in detail for its importance in understanding the sciences of
the human, and also in avoiding dangerous exaggerations of the potential
scope of some of these sciences (Dupré 2001), but this is not my central topic
here. Now I want only to point out how inevitable this pluralism should look in
light of the metaphysics of the human that I have been sketching. The
individual human as he or she exists at a particular point in time is a stage in a
process shaped by a partly unique biology and a highly idiosyncratic set of
environmental conditions. Both the current properties of an individual and
their future possible trajectories are shaped by this specific constellation of
causes. This diversity does not at all imply that there may not be useful
statistical generalizations about populations of humans, with a range of
application depending on the topic in question, and with the potential to
ground useful scientific models. But the idea of some account of human
nature that could underlie a complete account of what humans do always and
everywhere is a fantasy.
Conclusion: Human Nature Again
Theories involving well-chosen partial perspectives can be useful and even
indispensible. But they also carry the obvious and serious risk that ignoring
significant factors can cause major error. Surely the most dangerous example
of this in the life sciences is the abstraction from environmental factors in
purely genetic models of development and of evolution. Here we find a real
asymmetry between the defenders of nature and nurture described at the
beginning of this talk. No one imagines that development or evolution can be
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explained entirely abstracted from genetics; that a human baby brought up by
elephants will grow into an elephant, for instance; or that living among large
expanses of bamboo will cause us to evolve into giant pandas in a few
generations. But many people think that development can be studied more or
less entirely as caused by genes; and though evolutionists will always see the
environment as important in providing the conditions in which natural selection
operates, they quite standardly treat it as a static background condition rather
than a dynamic variable. Abstraction is always tempting as providing
manageable and illuminating simplification. But in a topic such as that of
human nature certain tempting abstractions can be disastrous, most notably
the excessive focus on genetics.
So what is human nature? Humans I have said are life cycles, a kind of
process. The significance of this might be illustrated by considering the transhumanist dream of freezing human development for centuries at some
preferred point in adulthood. If it is held that humans are a kind of thing,
which takes a few decades to develop and then a few more to decay, it is a
natural thought that one should do everything one can to retard this decay.
From a processual perspective the envisaged change is a much more radical
distortion of human nature, a complete reorganization of the life cycles that we
are. The problems often noted with the reformation of the temporal relations
between the generations of lifecycles that constitute the human reproductive
lineage are perhaps even more significant. I don’t mean to say that any of
this is necessarily bad; just that it is important to see what a drastic shift this
idea involves in the kinds of beings we are. And perhaps the recognition of
the extent of this change also suggests that it may be a lot harder to achieve
even than some of its advocates imagine.
Humans are highly flexible, developmentally plastic, life cycles. Evidence for
this claim includes the geographic and historical diversity of human lives and
societies and, perhaps equally important, the increasing realization that
developmental flexibility is pervasive throughout the living world. The
hypertrophied human brain is not a device for importing obsolete behavior
patterns from the Stone Age, but rather for carrying behavioral plasticity to a
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level unprecedented in evolution. The vast success of the human species, if
admittedly not yet a very long-lasting success, suggests that this flexibility is
highly adaptive.
Flexibility is of course constrained by physiology. We cannot learn to fly or to
swim in the deep oceans in pursuit of giant squid. If we want sonar we will
need to build machines. And physiology constrains our psychology in deep
though very general ways. Like all animals we care a lot about eating, and
like most we care a lot about sex and raising children. We are a highly social
species, a fact connected to our large brains that allow diverse and
complementary specialization and division of labour, and our lack of
especially impressive individual physical capacities. But what we eat, how we
have sex and with whom, and how we raise our children are highly diverse.
Similarly our profound sociality is realized in a hugely variable range of social
systems, which provide a bewildering array of possible social roles. There are
many species that are interested in food and sex, and many that are social; it
is the developmental plasticity that is our peculiar distinction.
A senior advisor to the UK recently announced publicly that research had
shown that 70% of a child's performance is genetically caused. One
supposes that he was referring to a measure of heritability, a claim that a
certain proportion of the variation in educational outcome could be explained
by genetics, a fact that says more about the variability of schools than about
the causation of educational outcomes. The problem with such
pronouncements from such a source is that they are of course intended to
influence policy, for example by diverting resources from unsuccessful
students, assumed to have ‘bad’ genes, supposed in turn to doom their
possessors to poor outcomes. It is depressing to find these vulgar
misunderstandings of genetics in the corridors of power, but perhaps the best
way of addressing them is to promote better understanding of the open-ended
and diverse processes that are human lives.
Returning for a final time to the debate with which I began, I have said that my
sympathies lie more with the deniers of human nature than its defenders; but I
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prefer to say not that there is no human nature, but that human nature is
uniquely plastic. Though there is of course something that humans are like,
and that we should be concerned to describe and understand, the concept of
human nature is generally used to circumscribe the range of human variation
and possibility in ways that are ungrounded by the empirical facts about us.
This does not mean, on the other hand, that I subscribe to the extreme
existentialist view that we are entirely free to be whatever we choose. In fact
human diversity and even the initial underdetermination of human life cycles is
entirely consistent with the view that human lives are fully determined. It is
just that the causal factors that will determine them are not settled in advance.
A human life might be like the career of a stick floating down a turbulent river:
no one could predict where it would end up, but this would not show that the
stick had any choice in the matter.
As a matter of fact I think the metaphysics of a person as a substantially
undetermined process does leave room for an interesting and important
conception of human freedom, or for a kind of self-determination. But that is a
story for another time.
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