III. EVOLUTIONISM REBORN
The rebirth of evolutionism is associated with the
advance of the natural sciences in the period after the
Renaissance. Several stages in the process of rebirth
can be distinguished. The first was a result of the new
cosmogony. Theories of how the physical universe,
including the solar system, had been or might have
been produced in accordance with mechanical laws
were set forth by René Descartes in his Principles of
Philosophy (1644), by Immanuel Kant in his Universal
Natural History and Theory of the Heavens (1755), and
by Pierre Simon de Laplace in his Exposition of the
System of the World (1796). As a consequence, the idea
that nature had a history emerged as a powerful rival
to the dogma of special creation, even though
Descartes presented his theory as a purely imaginative
exercise which was not intended to contradict the first
chapter of Genesis. Furthermore, the new cosmogony
supposed that originally the matter of the universe was
in a chaotic, nebular state from which it passed through
a succession of orderly changes to its existing complex
structure. Isaac Newton's Principia Mathematica (1687)
had given a definitive account of that structure, but
had said nothing about how nature developed. Yet it
was an obvious move to apply Newtonian principles
to cosmogonic problems, and thereby bring to the fore
the idea that the universe had developed in an orderly
way from an unorganized state.
A second phase in the rebirth of evolutionism was
due to the rise of geology and paleontology. These
sciences established three conclusions that were essen-
tial to the revival of evolutionary views.
(1) The changes in the surface features of the earth
through the ages are the result of physical forces whose
operation has been gradual and broadly constant. This
uniformitarian doctrine replaced the ancient biblical
story of the Flood, and also the conception that the
earth's surface had been subject to periodic catas-
trophes. The classical version of uniformitarianism
appeared in Sir Charles Lyell's Principles of Geology
(1830), a work that profoundly influenced the thought
of Charles Darwin.
(2) The age of the earth is far greater than biblical
chronology allowed. In 1650 Archbishop Ussher calcu-
lated that the Creation took place in 4004 B.C. A
century later, Buffon conjectured that some seventy
thousand years had elapsed since the molten earth
began to cool. By the beginning of the nineteenth
century, the age of the earth was estimated in millions
rather than thousands of years. This expansion of the
terrestrial time scale provided the setting needed for
the doctrine that biological evolution tends to take
place slowly.
(3) The fossils or “figured stones” which had been
noticed in the earth's crust ever since antiquity and
which posed an enigma to nonevolutionists, are in fact
the remains of organisms that lived in the past. One
of the first to support this conclusion was Leibniz
(Protogaea, 1680), although he did not surmise how
much time was needed for petrifactive processes to
occur. Later, Buffon and Maillet formulated geological
theories to account for the presence of fossils, but their
views were subjected to ridicule by Voltaire who was
hostile to the idea of development in nature (Haber,
1959). By Lyell's day, however, it was clearly under-
stood that many fossils were relics of species long
extinct, and that observed or reconstructed sequences
of fossils were direct evidence for evolution.
