Evolution: Topic Index
These topics were written by Dr. Francisco Ayala, Professor
of Biological Sciences and Philosophy at the University of California,
Irvine. He is a member of the President's Committee of Advisors
on Science and Technology, and has been President and Chairman
of the Board of the American Association for the Advancement of
I advance three propositions. The first
is that Darwin's most significant intellectual contribution is
that he brought the origin and diversity of organisms into the
realm of science. The Copernican Revolution consisted in a commitment
to the postulate that the universe is governed by natural laws
that account for natural phenomena. Darwin completed the Copernican
Revolution by extending that commitment to the living world.
The second proposition is that natural selection is a creative
process that can account for the appearance of genuine novelty.
How natural selection creates is shown with a simple example and
clarified with two analogies, artistic creation and the "typing
monkeys," with which it shares important similarities and
differences. The creative power of natural selection arises from
a distinctive interaction between chance and necessity, or between
random and deterministic processes.
The third proposition is that teleological explanations are
necessary in order to give a full account of the attributes of
living organisms, whereas they are neither necessary nor appropriate
in the explanation of natural inanimate phenomena. I give a definition
of teleology and clarify the matter by distinguishing between
internal and external teleology, and between bounded and unbounded
teleology. The human eye, so obviously constituted for seeing
but resulting from a natural process, is an example of internal
(or natural) teleology. A knife has external (or artificial) teleology,
because it has been purposefully designed by an external agent.
The development of an egg into a chicken is an example of bounded
(or necessary) teleology, whereas the evolutionary origin of the
mammals is a case of unbounded (or contingent) teleology, because
there was nothing in the make up of the first living cells that
necessitated the eventual appearance of mammals.
I conclude that Darwin's theory of evolution and explanation
of design does not include or exclude considerations of divine
action in the world any more than astronomy, geology, physics,
or chemistry do.
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| Contributed by: Dr. Francisco Ayala