II. ANTI-EVOLUTIONISM
The impetus of evolutionary thinking among the
Greeks was brought to an abrupt halt by the work of
Plato and Aristotle. Both of these influential thinkers
held views that were incompatible with any conception
of irreversible, cumulative changes taking place in the
real world. Plato maintained that the real world is a
realm of unchanging forms or archetypes apprehended
solely by thought. Things perceived by the senses are
imperfect copies of forms and are less than fully real.
When applied to living organisms this conception had
anti-evolutionary consequences. It implied that the
characteristics of organisms are to be explained by
resemblance to ideal archetypes, not by descent from
ancestors who had undergone changes of form and
function over long periods of time. Furthermore, this
Platonistic conception became a basis for classical
taxonomy in which plants and animals were classified
into kinds that are sharply demarcated and allow no
intergrading. This typological classification acted as a
block to the idea of a gradual transmutation of one
species into another. Evolutionary taxonomy is still in
the process of detaching itself from the influence of
Platonism (Simpson, 1961).
Aristotle represented the real world as a hierarchy
of kinds of things, each of which combines form and
matter. In his biological writings, however, he recog-
nizes that living organisms are not sharply classifiable
into kinds, for there are many intermediate types which
blur the lines of demarcation. He even says in one place
that “nature passes from lifeless objects to animals in
an unbroken sequence.” These views have led some
students to conclude that Aristotle must have been an
evolutionist. But such a conclusion is mistaken. It
wrongly supposes that because the affirmation of con-
tinuity in the living world is incompatible with a belief
in sharply discrete kinds, it implies that a historical
derivation of one kind from another must have taken
place. Aristotle certainly did not think that the inter-
grading of organisms had come about historically. It
would have been inconceivable to him that one species
of animal could slowly change into another species,
just as it would have been inconceivable that the com-
plex hierarchy of nature could have been gradually
developed from simple beginnings. For him the uni-
verse is eternal and unchanging. In it every thing has
its fixed nature which remains unaffected by the motion
which brings about its actuality from a state of potency.
The profoundly anti-evolutionary character of Aris-
totelianism helped to arrest all forms of evolutionism
for nearly two thousand years.
Another influence that worked in the same direction
during this period was Christianity. After the time of
Aristotle, there were occasional revivals of the idea
that living things had arisen naturally from terrestrial
elements and that human society had developed from
a state of barbarism. Lucretius, Cicero, and Horace
all advocated views of this kind. But such views were
eclipsed when the Christian world-outlook became
predominant in Europe. An essential part of this out-
look was the biblical story of creation, according to
which the universe was brought into being by an all-
powerful God who had made it complete in every
detail, with each kind of creature occupying its proper
place in the whole. The period since the creation was
relatively brief, being only a few thousand years. Adam,
the first man, was created by God in His image, and
hence could not possibly have had ancestors. The
human race is, indeed, central to the cosmic drama
which is being worked out according to the divine
plan. The rest of the universe merely forms the back-
ground for what is taking place. Thus the static cre-
ationism taught by Christianity made it difficult for
any idea of evolution to arise, let alone be defended.
