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Phil*2070
Notes on Kricher- the problems with biological essentialism
Prof. Linquist
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1. Biology’s essentialist hangover
In this section I describe a popular framework for categorizing and explaining
species, ecosystems and other biological entities. This framework, called
essentialism or ‘typological thinking’, has cultural roots reaching back to Plato and
Aristotle. Since the rise of Darwinism, however, essentialism has been on the decline
within the biological sciences. In what follows I will present the basic tenets of the
essentialist view of species, explaining why this perspective has been overthrown by
Darwinism. I will then pose the question whether essentialism in environmental
philosophy is destined for a similar fate. Two ecological ideas are particularly closely
bound to essentialism. First, the idea that biotic communities are tightly integrated wholes. Second, the
idea that there is a balance of nature. You will recognize these ideas as central to Leopold and Callicott,
as well as to environmentalism more broadly. Yet, as we shall see, these notions become questionable
once the essentialist foundation on which they rest is shaken.
2. Species essentialism.
Consider this question. What makes a particular organism a member of one species rather than
another? Take the spruce tree growing in my back yard, which I call Willard. What makes Willard a blue
spruce as opposed to a red cedar? Perhaps you think that each species is defined by a collection of
(essential) traits. Willard is a blue spruce because it has waxy needles, grey bark and produces purple
cones in the spring. If Willard had green needles and papery, red bark, then he might be a red cedar.
This was the way that Aristotle and Plato would have answered our question. These essentialists
explained an individual’s species membership in terms of its form, which was like a blueprint
determining its appearance and behaviour. Today we are perhaps a little more sophisticated. Instead of
forms we speak of genes. What makes Willard a blue spruce rather than a red cedar, you might think, is
its DNA. Genetics has become, in popular culture at least, the modern day essentialism.
Consider another question. How much modification would it take to change Willard from one species to
another? Essentialism says that some of Willard’s (non essential) traits can be altered without changing
its species. Pruning him or painting him orange doesn’t change his essence. Other traits are more
central. To modify Willard so that he grows a different bark or needles, that might modify his species
membership –or so the essentialist would maintain. These central traits are essential traits, whereas the
malleable ones are called accidental traits. This distinction between essential and accidental traits is
important to essentialism.
Here is a third and final question. Suppose that Willard breeds with another spruce tree and they have
offspring. These offspring will almost certainly vary. Some might grow more rapidly than others. Some
might produce more purplish cones. Maybe an extreme variant will grow differently shaped needles.
The third question is how to account for this variation. The essentialist thinker explains variation in
terms of deviation away from the ideal. Usually this deviation is described as a sort of aberration or
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Notes on Kricher- the problems with biological essentialism
Prof. Linquist
corruption. Genetic mutations or diseases, for example, cause an organism to deviate from the way it
was ‘supposed’ to turn out. The metaphor of a developmental target is apt here. Essentialists view the
embryo as containing a blueprint that specifies what it is supposed to achieve. Any deviation away from
this ideal is explained in terms of a disruption to the genetic ‘plan’. Regardless of whether one attributes
disruption to random mutation or a developmental defect, the idea that organisms are supposed to turn
out a certain way often lurks in the background.
To summarize, there are three central ideas behind species essentialism:
(1) Each individual has an essence that defines the way that it is ‘supposed’ to be.
(2) There is a distinction between essential and accidental features. Modifying essential, but not
accidental features will change the organism’s identity.
3) Variation among individuals is explained in terms of their deviation away from the ideal
essence. These aberrations away from the ideal type result from a corruption to the essence.
Let us now consider how the Darwinian framework does away with these ideas in the case of species.
3. The Darwinian rejection of species essentialism
After Charles Darwin we no longer think that species are defined by some inner essence, genetic or
otherwise. On the Darwinian view a species is a lineage of successive generations. This is quite a
different way of thinking about class membership than many people are used to. For example, we are
used to thinking about chemical substances in terms of their essential properties. What makes a nugget
of gold a member of its class rather than a member of the class of lead objects?
The answer is that it has an essence, defined by its chemical composition (its
atomic weight, to be exact). A hunk of lead, similarly, is determined by its
chemical properties. These entities have genuine essences; species do not.
Instead, a species is more like a family. What makes you a member of the same
family as your cousins? Is it that you resemble one another? Of course not! It is
that you stand in the right familial relationship to one another. Nor is it necessary
for one to share a certain amount of genes with one’s family members. Adopted
family are family nonetheless. Family membership is what philosophers call a
relational (as opposed to an essential) property. Your family consists entirely of a set of relations to
other people. The same goes for species. What makes two organisms members of the same species has
nothing to do with how they look or even with their DNA – it rests entirely on their descent. Species are
lineages of descent through space and time, nothing more and nothing less. Once again, this view of
species is relatively new compared to the essentialist view, which defines species in terms of a corse set
of shared traits. To be clear, I am not denying that species often resemble one another. The point is that
they are not defined as a class in terms of this pattern of resemblance.
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Notes on Kricher- the problems with biological essentialism
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A second feature of the Darwinian view of species is that they lack
essential traits. As a lineage, it is possible to change any of the traits
in an organism without modifying its species membership. Zebras
could lose their stripes. Giraffe necks might shorten. Blue spruce
trees might adapt to warmer climates by changing their leaf
structure. Any given trait might come or go in a lineage, this would
not affect its status as a distinct species. A stripe-less zebra is still a
zebra.
Finally, Darwin also introduced a different way of thinking about variation. He replaced typological
thinking with what is known as population thinking. Instead of looking at variation as deviation from
some ideal type, Darwin viewed variation as a basic fact of existence. Construction of an ideal type is an
artificial abstraction. Perhaps the simplest way to think of population thinking is with the slogan:
variation is the norm.
Consider an example of how Darwin viewed his beloved barnacles, a favourite object of his research.
Darwin travelled to different parts of the English coastline and noticed considerable differences in the
shapes barnacles, even ones belonging to the same species. In areas where the water was calm,
barnacles were more elongated and thinner shelled. In areas with intense wave action, barnacles were
more stout and thick. The question “what is the typical barnacle?” has no answer for Darwin. He was
interested in explaining the extent to which barnacle populations vary, and the causes of this variation.
This inverts the essentialist view. Instead of thinking of variation as deviation, now it is the norm or
average which is seen as the abstraction. Once again, variation is the basic fact of existence.
To summarize the populational view of species:
1) Species are lineages.
2) There is no distinction between accidental and essential traits, because no traits are essential to
any species.
3) Variation is the norm.
4. Typological thinking in community ecology
The ecologist John Kricher remarks that,
“Given the view that each species is intricately and immutably crafted (by whatever force), it is
not much of an intellectual jump to assume that natural assemblages of species, namely
ecological communities, are fundamentally balanced, which was, indeed, the Greek view of
nature. The concept of balance of nature, a view in which species are highly and, in many cases,
precisely interdependent, thus derives at least in part from an erroneous notion of the very
nature of species. Therefore, the view that all of nature is somehow balanced is also largely
artificial” (1998, 166).
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Notes on Kricher- the problems with biological essentialism
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This is by no means a minority view among modern ecologists. Few accept the idea that communities
are in a delicate balance, or that ecological communities are tightly integrated wholes. However, like the
essentialist view of species, these ideas persist in popular culture. In this section I will clarify these
concepts and attempt to draw their connection to essentialism. In the following section I will identify
some of the evidence against these ideas.
The term `ecological community admits of no precise definition. Roughly speaking, a community consist
of an assemblage of species that are typically found in a given region. Hence people speak of an
intertidal community as being composed of barnacles, some sea weeds, algae, crabs and some fishes.
Forest communities and grassland communities are similarly composed of a usual cast of biological
characters. The specific species composing a community varies from one region to another. Intertidal
communities in British Columbia are composed of different species from their New Zealand
counterparts.
A key feature of communities is that they are relatively stable from one year to another. That is to say
that the types and abundances of species found in a community do not change radically over short
(annual) periods. This much is agreed. To say anything more about the underlying processes maintaining
those stable patterns is to enter into more controversial territory.
A view that dominated ecological science of the 1930s and 1940s regarded ecological communities as
superorganisms. There are at least three components to this view. The first component is that the
members in a given community (the species that occur there) are highly interdependent. Removing or
modifying one species, on this view, will have cascading effects throughout the system. Leopold and
Callicott endorse this idea. They appeal to the interdependence of biotic communities as a justification
for why we should value their stability and integrity. At one point Leopold argues that people who are
concerned with economically significant species should also respect the non-economically significant
ones, because the former are highly dependent on the latter. This betrays a conviction that ecological
communities are superorganisms.
A second component of this view regards ecological communities as having a stable equilibrium. To say
that a system has a stable equilibrium means that if it is perturbed away from equilibrium, it will drift
back to equilibrium on its own. This idea has obvious resonance with the essentialist mode of explaining
variation. In both cases, deviation is explained with respect to an ideal of how the entity is ‘supposed’ to
be.
In defence of this equilibrium view ecologists of the 1930s and 1940s emphasized the way that forest
communities seem to behave after a disturbance. Typically there is a succession of stages over which recolonization occurs. Early ‘pioneer’ species (e.g. grasses and shrubs) are followed by small, fast growing
trees, which are eventually replaced by the ‘climax’ species such as large hardwoods. This phenomenon,
called ecological succession, was interpreted by Odum as evidence that forest communities are in stable
equilibrium. When they reach their final stage, it was assumed, the community remains in that state
indefinitely. Likewise, perturbing it from that state causes it to return on its own. There is a further
lesson that some have drawn from the phenomenon of succession. Some thinkers have compared this
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Notes on Kricher- the problems with biological essentialism
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process to the biological development (growth) of an organism. Development seems to head towards an
end-state. It seems to be goal directed. By extension, it would appear that succession is evidence that
ecological communities have goals. To the essentialist, those goals define the ways that communities
are ‘supposed’ to be.
As Kricher points out, environmentalists often point to these ideas of community equilibrium and
succession when attempting to give substance to the idea that there is a balance of nature. This idea of
nature’s balance is the community-level expression of essentialism’s understanding of variation. Each
community is seen as having a central tendency – a point at which it is in balance—and factors that
cause change are seen as a type of corruption. If one combines the idea that communities are highly
interconnected, then this alleged balance seems all the more delicate. One gets the impression that any
disturbance is bad, in the sense that it corrupts the community’s essence, and furthermore that this
corruption can amplify through the tightly interconnected system.
A third and final component of the superorganismic view of communities is that once they are in
equilibrium, they remain static. I touched on this idea in the previous paragraph. The assumption is that
once a community has reached its equilibrium state, species composition will not change as long as it
remains unperturbed. This is reminiscent of the idea that a species has a set of essential properties that
does not change over the course of its existence.
5. The populational view of communities
As with the essentialist view of species, the essentialist view of communities remains the dominant
perspective in popular culture. It is therefore important to sketch the alternative viewpoint. The
‘populational’ view of communities (as I call it here) has much in common with the populational account
of species that followed after Darwin.
The first part of the populational account of communities rejects the idea that they are tightly
integrated wholes. It is important to understand what is being rejected here. The populationist does not
deny that the addition or removal of some species can have cascading effects throughout the
community. This is most pronounced in cases where a single predator is the primary factor limiting the
abundance of another species. The removal of that one predator often causes prey populations to
explode. A classic example is the effect that removal of sea otters had on kelp forests. Otters normally
prey on sea urchins, so when otters were hunted to local extinction in the 19th century, urchin
populations exploded. This resulted in a major decline in the size of kelp forests, since urchins are a very
efficient kelp forager with few other predators. You can read more about this relationship in the
following (excellent) summary:
http://mypage.direct.ca/r/rhsu/otters.html
The populationist does not deny (obviously) that such interdependencies exist. However, it is a mistake
to assume that all species in a community are similarly interdependent. There are many species that one
could remove from a community with little downstream effect. Ecological communities are not always
as tightly interconnected as the community essentialist assumes. This is a point that Kricher mentions in
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Notes on Kricher- the problems with biological essentialism
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his paper. You might also be interested in researching this issue yourself. There are many articles
available on Google Scholar investigating the effects of removing particular species from a community.
Here are links to some recent research ( a small fraction of what’s out there):
http://www.nature.com/nature/journal/v435/n7043/full/nature03611.html
http://www.phy.umist.ac.uk/~ajm/qhm05a.pdf
There is another way of looking at the holistic account of community composition. This view holds that
communities are highly interdependent. Hence, the composition of species in an area is determined by
the other species that occur there. The philosopher Kim Sterelny has a nice metaphor for this view. He
claims that holist thinks of species in a community like they are individuals at a party. If you want to
know why a given individual will be at the party, the answer usually depends on whom else is there.
Ecologists describe this view by saying that community membership is determined by biotic factors (i.e.
other living organisms)
At the other extreme, populationists view the species in a community like individuals at the beach. If
you want to know why an individual is at the beach, the answer has little to do with whom else is there
and more to do with the sun and the sand. Ecologists say that the composition of these communities is
organized by abiotic factors. Abiotic factors include temperature, moisture, Ph, sunlight and any other
feature of the environment that is not alive.
Obviously these two categories (biotically and abiotically determined communities) represent opposite
ends of a continuum. Actual communities exist somewhere between these extremes. My point at this
stage is simply to identify that there is an alternative to the holist position, and to suggest that
communities are closer to the abiotically determined end of the spectrum than the essentialist
perspective suggests.
Recall that the essentialist view of communities holds that they are defined by a core cluster of species.
This is one of the main points that Kricher attempts to overthrow. He notes that North Eastern forest
communities have seen members come and go over the past 10,000 years. Some species have invaded,
others have gone extinct. No single set of species can be considered essential to these communities.
Kricher notes that this constant rate of turnover only becomes apparent over an extended period of
time. Our limited perspective on communities gives the mistaken impression that they are static. This is
all very reminiscent of the populational account of species identity. Recall that according to this view
there is no essential cluster of traits that defines a species’ essence. Instead, particular traits come and
go according to environmental changes and the populations’ adaptation to those changes. Here too,
the change in a species’ characteristics is not obvious to the naked eye – one must observe them over
extended periods.
A final aspect of the populational view of communities challenges the idea balance of nature concept.
Earlier I interpreted this idea in terms of a stable equilibrium. I noted that the phenomenon of ecological
succession was cited by ecologists in the mid 20th Century to suggest that communities returned to
equilibrium after a disturbance, and therefore that there is an essence guiding them towards an ideal
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Notes on Kricher- the problems with biological essentialism
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state. Kricher argues that even in the case of North Eastern forests—once heralded as a paradigm case
of ecologcial succession— these ideas do not apply. He notes that these communities have never
maintained a stable composition for any significant period of time. Instead there has been continual
species turnover for the past 10,000 years. So called ‘climax’ communities, which were once thought to
have reached equilibrium, are no less immune to invasion from foreign species, Kricher maintains,
compared to earlier stages. Change in these communities is not appropriately understood in terms of
an ideal state towards which they are internally directed. The composition of these communities is
determined instead factors external to the community. These are abiotic factors like temperature and
moisture. The essentialist views these changes as a deviation from the stable equilibrium state.
However, Kricher’s point is that when the community is viewed over an extended period, there is no
stable equilibrium to speak of. A final consideration raised by Kricher is that humans have had an impact
on these communities that goes well before the first contact by Europeans. Perhaps our species is just
the most recent one to leave its mark on the ecology of this region. The populational view invites us to
consider variation in this community as the norm, rather than as a corruption of how it is supposed to
be.
6. Conclusion
I have not addressed the implications of this shift in thinking, from essentialist to populationist
perspectives, on our normative attitudes towards nature. The essentialist view had normativity built
into it: there was a certain way that communities were ‘supposed’ to be, and any deviation from that
equilibrium was seen a kind of corruption. However, on the populational view this idea makes less
sense. Communities, like species, are in a constant state of flux, they are not as tightly integrated as it
was once assumed, and variation is the norm. Ecologists like Kricher now regard essentialism as a
cultural vestige left over from an era when our perspective on nature was limited to a brief spatiotemporal snapshot.
But if communities have no essence, if they are truly in a constant state of flux, what does this say about
our conservation duties towards them? Should we strive to prevent change from happening? Should we
resist harming any organisms out of fear that it will disrupt nature’s ‘delicate balance’? It is far from
clear that these attitudes can be sustained under the populationist view. Perhaps this tension explains
part of the reason why the essentialist perspective retains its grip on popular thinking.
The following lecture we will consider a popular movement that arose at around the same time that the
populationist account of species began to take hold. The Deep Ecology movement rejects the very
scientific framework on which the populationist view is based. We are used to thinking that if science
tells us that communities lack an essence, then so much for the essentialist perspective. This is what is
happening in the case of species essentialism. However, Deep Ecologists turn this line of reasoning on its
head. If science tells us that communities lack essences, they claim, then so much for science.
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Notes on Kricher- the problems with biological essentialism
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7. Questions for further consideration:
1. What are some of the biological examples that Kricher uses to defend what I have called the
‘populationist’ view of species?
2. What are the three features of the essentialist view of communities?
3. What is the link between essentialism and the idea of a balance of nature?
4. Does the populational view of communities, if it is correct, impact the way that you regard your
relationship to nature?
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