Leopold wants to think about ethics in evolutionary
terms. His background is as a
biologist. Philosophically speaking, an
ethic is what distinguishes social from anti-social behavior. In other words, an ethic says what you should
and should not do. Ecologically
speaking, an ethic is a restriction on individual behavior in the struggle for
life. Leopold says that the sequence of
ethical evolution is to recognize a broader range of entities as being morally
relevant. For example, in the history of
Western Civilization, women and various other minorities were, at one point or
another, thought to be morally irrelevant.
Many humans were once considered property. Property issues are not moral issues. But just as we now recognize that women and
minorities are not property, Leopold thinks that we have good reason to think
of land as more than property. Land has
moral value even if we do not love, respect or admire it.
What is the basis of the value of the land? Leopold describes what he calls the land
pyramid. At the base of the pyramid is
the soil. Plants live on the soil,
insects live on the plants, rodents and birds live on the plants, and smaller
predators live on birds, rodents and plants.
Apex predators occupy the top of the pyramid, as they are consumed by no
other creatures. Beings near the top
feed off of beings lower on the pyramid.
Beings at the bottom are nourished by the decaying matter of higher
species. Leopold says that the way this biological community
functions is like an energy circuit.
Energy (nutrition, calories) transfers from the lower levels to the
higher levels and back down. Natural and
native species keep this energy circuit open.
Sometimes, invasive or introduced species interrupt this energy
circuit. For example, the kudzu vine
will cover all native plant species and rob them of energy from the sun. When local plants die, local insect populations
do not get appropriate nutrition. Hence,
local rodent and bird populations suffer, as well. Eventually, this domino effect reaches apex
predators. Whereas natural changes in
biological communities are slow and local, man-made changes are fast and
large-scale.
Humanity can either think of itself as a conqueror over
nature or as in community with nature.
Leopold says that attempts to be conquerors will be self-defeating
because true domination and control require perfect knowledge of how nature
functions. Because we lack this perfect
knowledge, we cannot control nature.
Also, a long history of attempts to control nature show that our
scientific and technological efforts are often met with negative consequences
that are neither foreseen nor intended.
As such, we should recognize that just as species within a biological
community have co-evolved in order to function as a larger system, we are also
part of the biological community. We are
not masters of nature. We are in
community with natural systems and species.