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State of the question. The question of the origin of
life and of the different species of living things is one
of the most important of those that pertain to the creation
of corporeal things. The modern theory of transformism
was scarcely mentioned among the ancient philosophers,
although St. Thomas sometimes spoke of the hypothesis of
the appearance of new species.[1261] This problem
is in some way connected with the old question of
universals: whether the universals are fundamentally in
individual beings according to their unchangeable nature.
Transformism may be either absolute or moderate.
Absolute transformism holds that matter is uncaused, that
it exists of itself from eternity, and that from it by
successive transformations have issued different living
beings, that is, vegetative, sensitive, and
intellectual life. (Huxley and Darwin.)
Moderate transformism holds that matter is not uncaused
but is created by God, that it is not eternal, that the
first living beings were created by God, and that God
intervened in a special way to produce sensitive life, in
the formation of the human body and in the creation of the
spiritual soul. This moderate transformism refers to the
production of various species of plants and animals which
derive by successive transformations from the first living
beings. Some of those who hold a moderate transformism
think that all plants and animals come from different
species created by God; others think that all plants came
from one species and all animals came from one species of
animal. Those who support the theory of transformism are
not agreed on the definition of species; what one calls
species another may call a variation.
Absolute transformism. This theory manifestly
contradicts faith and reason inasmuch as it denies all
intervention by God. It is directly opposed to the dogma
of creation ("In the beginning God created heaven and
earth"), since it teaches that matter has no cause and
is eternal. This theory is opposed to all the proofs for
the existence of God, and it implies that more is
produced by less, the more perfect by the imperfect.
This is at the same time against the principle of
contradiction or identity, against the principle of the
reason of being, the principle of efficient causality,
and the principle of finality. It implies an ascending
evolution, in which something more perfect appears without
any reason, without any efficient cause, without an end,
and without order. This theory destroys all
intelligibility of things, as we have explained at length
on another occasion.[1262] Such an evolution of
species would be entirely fortuitous, without any
preconceived idea or finality, and no reason is supplied
for the wonderful subordination and coordination of things
in nature.
In even the most ancient species, as we know from
fossils, the organs are adapted to an end, coordinated
with one another, and subordinated to the preservation of
the individual and the species. All this cannot be
attributed to chance; it presupposes an intelligent
cause. Chance is a cause "per accidens", a
cause that is accidentally connected with a cause "per
se", and therefore an accidental cause cannot be the
first cause of the order in things, for then order would
come from the privation of order, and intelligibility
would come from unintelligibility. What would be more
absurd than to say that the intellects of the great doctors
and the charity of the saints derived from a blind and
material fate? The greater cannot be produced by the
lesser. Hence absolute transformism substitutes the most
patent absurdity for the mystery of creation.
This refutation of absolute transformism is confirmed by
experience, which shows that every living thing comes from
another living being and that there is no spontaneous
generation. Pasteur and Tyndall demonstrated that no
living beings are generated where all ova and seed have
been destroyed. Such bacteria as are said to be generated
in the atmosphere do not come from inanimate matter but
from ova existing in the atmosphere. Huxley himself
admitted Pasteur's conclusions.
St. Thomas held that certain animal life was generated
by putrefaction under the influence of the sun. His
explanation was as follows: "A heavenly body, since it
is a moving thing that is moved, has the nature of an
instrument which acts with the power of the principal
agent; and therefore it can cause life by virtue of its
mover, which is a living substance."[1263] St.
Thomas never admitted that the more perfect being can be
produced by the less perfect.
Moderate transformism. This theory does not oppose the
teaching of faith. The words of Genesis ("And God
said: Let the earth bring forth the green herb, and such
as may seed, and the fruit tree yielding fruit after its
kind") show that there was some difference among the
species that God created, but they do not assert that all
species were immediately created by God. St. Thomas
himself said: "If certain new species should appear,
these have existed previously in certain active forces; in
this way what is generated by animal putrefaction is
produced by the power of the stars and the elements,"
that is, "by the power of the mover (of the stars),
which is a living substance."[1264] Thus St.
Thomas maintains inviolate the principle of causality,
according to which the more perfect cannot be produced by a
less perfect being as a fully sufficient cause.
Lastly, it is difficult to say where true variation
begins and where species leaves off in the ontological
sense. Generally interfecundation is held to be the sign
of membership in the same species. If it is pointed out
that the horse and the ass generate the mule, it should be
remembered that the mule is sterile, that is, it does not
propagate a species. Here we have confirmation of the
principle that operation follows being, and the mode of
operation follows the mode of being; from this it follows
that every animal generates offspring similar to itself in
species. Ontological species therefore are immutable.
But it is difficult to say when two animals belong to the
same species properly so called or to two similar species.
We do not have a clear enough understanding of the
specific difference between living sensible beings; their
specific forms are deeply immersed in matter and hardly
intelligible to us. We know them only in a descriptive
manner, empirically.[1265]
But when we come to man, we clearly understand his
specific difference because it is not immersed in matter.
Man's reason or rationality is a form of
intellectuality, and intelligence is distinctly
intelligible to itself because it is essentially ordered to
the cognition of intelligible being itself and the reasons
for the being of things.
It is clear, then, that the human soul cannot be educed
from the potency of matter; on the other hand the specific
form of plants and animals is educed from matter by way of
generation.[1266]
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