THEORY OF DEVELOPMENT ACCORDING TO KANT AND LAMARCK.
Kant’s Dualistic Biology.—His Conception of the Origin
of Inorganic Nature by Mechanical Causes, of Organic
Nature by Causes acting for a Definite
Purpose.—Contradiction of this Conception with his
leaning towards the Theory of Descent.—Kant’s
Genealogical Theory of Development.—Its Limitation by
his Teleology.—Comparison of Genealogical Biology with
Comparative Philology.—Views in favour of the Theory of
Descent entertained by Leopold Buch, Bär, Schleiden,
Unger, Schaafhausen, Victor Carus, Büchner.—French
Nature-philosophy.—Lamarck’s Philosophie
Zoologique.—Lamarck’s Monistic (mechanical) System of
Nature.—His Views of the Interaction of the Two Organic
Formative Tendencies of Inheritance and
Adaptation.—Lamarck’s Conception of Man’s Development
from Ape-like Mammals.—Geoffroy St. Hilaire’s, Naudin’s,
and Lecoq’s Defence of the Theory of Descent.—English
Nature-philosophy.—Views in favour of the Theory of
Descent, entertained by Erasmus Darwin, W. Herbert,
Grant, Freke, Herbert Spencer, Hooker, Huxley.—The
Double Merit of Charles Darwin.
The teleological view of nature, which explains the phenomena of the
organic world by the action of a personal Creator acting for a definite
purpose, necessarily leads, when carried to its extreme consequences,
either to utterly untenable contradictions, or to a twofold (dualistic)
conception of nature, which most directly contradicts the unity and
simplicity of the supreme laws which are everywhere perceptible. The
philosophers who embrace teleology must necessarily assume two
fundamentally different natures: an _inorganic_ nature, which must be
explained by causes acting _mechanically_ (causæ efficientes), and an
_organic_ nature, which must be explained by _causes acting for a
definite purpose_ (causæ finales). (Compare p. 34.)
This dualism meets us in a striking manner when considering the
conceptions of nature formed by Kant, one of the greatest German
philosophers, and his ideas of the coming into being of organisms. A
closer examination of these ideas is forced upon us here, because in
Kant we honour one of the few philosophers who combine a solid
scientific culture with an extraordinary clearness and profundity of
speculation. The Königsberg philosopher gained the highest celebrity,
not only among speculative philosophers as the founder of critical
philosophy, but acquired a brilliant name also among naturalists by his
mechanical cosmogeny. Even in the year 1755, in his “General History of
Nature, and Theory of the Heavens,”(22) he made the bold attempt “to
discuss the constitution and the mechanical origin of the whole
universe, according to Newton’s principles,” and to explain them
mechanically by the natural course of development, to the exclusion of
all miracles. This cosmogeny of Kant, or “cosmological gas theory,”
which we shall briefly discuss in a future chapter, was at a later day
fully established by the French mathematician Laplace and the English
astronomer Herschel, and enjoys at the present day almost universal
recognition. On account of this important work alone, in which exact
knowledge is coupled with most profound speculation, Kant deserves the
honourable name of a natural philosopher in the best and purest sense of
the word.
If we read Kant’s Criticism of the Teleological Faculty of Judgment, his
most important biological work, we perceive that in contemplating
organic nature he always maintains what is essentially the teleological
or dualistic point of view; whilst for inorganic nature he,
unconditionally and without reserve, assumes the mechanical or monistic
method of explanation. He affirms that in the domain of inorganic nature
all the phenomena can be explained by mechanical causes, by the moving
forces of matter itself, but not so in the domain of organic nature. In
the whole of Anorganology (in Geology and Mineralogy, in Meteorology and
Astronomy, in the physics and chemistry of inorganic natural bodies),
all phenomena are said to be explicable merely by _mechanism_ (causa
efficiens), without the intervention of a final purpose. In the whole
domain of Biology, on the other hand—in Botany, Zoology, and
Anthropology—mechanism is not considered sufficient to explain to us
all their phenomena; but we are supposed to be able to comprehend them
only by an assumption of a _final cause_ acting for a definite purpose
(causa finalis). In several passages Kant emphatically remarks that,
from a strictly scientific point of view, _all_ phenomena, without
exception, require a mechanical interpretation, and that _mechanism
alone can offer a true explanation_. But at the same time he thinks,
that in regard to living natural bodies, animals and plants, our human
power of comprehension is limited, and not sufficient for arriving at
the real cause of organic processes, especially at the origin of organic
forms. The _right_ of human reason to explain all phenomena mechanically
is unlimited, he says, but its _power_ is limited by the fact that
organic nature can be conceived only from a teleological point of view.
Some passages are, however, very remarkable, in which Kant in a
surprising manner deviates from this mode of viewing things, and
expresses, more or less distinctly, the fundamental idea of the Theory
of Descent. He even asserts the necessity of a genealogical conception
of the series of organisms, if we at all wish to understand it
scientifically. The most important and remarkable of these passages
occurs in his “Methodical System of the Teleological Faculty of
Judgment” (§ 79), which appeared in 1790 in the “Criticism of the
Faculty of Judgment.” Considering the extraordinary interest which this
passage possesses, both for forming a correct estimate of Kant’s
philosophy, as well as for the Theory of Descent, I shall here insert it
_verbatim_.
“It is desirable to examine the great domain of organized nature by
means of a methodical comparative anatomy, in order to discover whether
we may not find in it something resembling a system, and that too in
connection with the mode of generation, so that we may no longer be
compelled to stop short with a mere consideration of forms as they
are—which gives us no insight into their generation—and need no longer
give up in despair all hope of gaining a full insight into this
department of nature. The agreement of so many kinds of animals in a
certain common plan of structure, which seems to be visible not only in
their skeletons, but also in the arrangement of the remaining parts—so
that a wonderfully simple typical form, by the shortening and
lengthening of some parts, and by the suppression and development of
others, might be able to produce an immense variety of species—gives us
a ray of hope, though feeble, that here perhaps some result may be
obtained, by the application of the principle of the _mechanism of
nature_, without which, in fact, no science can exist. This analogy of
forms (in so far as they seem to have been produced in accordance with a
common prototype, notwithstanding their great variety) strengthens the
supposition that they have an actual blood-relationship, due to
origination from a common parent; a supposition which is arrived at by
observation of the graduated approximation of one class of animals to
another, beginning with the one in which the principle of purposiveness
seems to be most conspicuous, that is man, and extending down to the
polyps, and from these even down to mosses and lichens, and arriving
finally at raw matter, the lowest stage of nature observable by us. From
this matter and its forces the whole apparatus of Nature seems to have
descended according to mechanical laws (such as those which she follows
in the production of crystals); yet this apparatus, as seen in organic
beings, is so incomprehensible to us, that we feel ourselves compelled
to conceive for it a different principle. But it would seem that the
archæologist of Nature is at liberty to regard the great _Family_ of
creatures (for as a Family we must conceive it, if the above-mentioned
continuous and connected relationship has a real foundation) as having
sprung from the immediate results of her earliest revolutions, judging
from all the laws of their mechanism known to or conjectured by him.”
If we take this remarkable passage out of Kant’s “Criticism of the
Teleological Faculty of Judgment,” and consider it by itself, we cannot
but be astonished to find how profoundly and clearly the great thinker,
even in 1790, had recognized the inevitable necessity of the Doctrine of
Descent, and designated it as the only possible way of explaining
organic nature by mechanical laws—that is, by true scientific
reasoning. On account of this one passage taken by itself, we might
place Kant beside Goethe and Lamarck, as one of the first founders of
the Doctrine of Descent; and considering the high authority which Kant’s
Critical Philosophy most justly enjoys, this circumstance might perhaps
induce many a philosopher to decide in favour of the theory. But as soon
as we consider this passage in connection with the other train of
thoughts in the “Criticism of the Faculty of Judgment,” and balance it
against other directly contradictory passages, we see clearly that Kant,
in these and some similar (but weaker) sentences, went beyond himself,
and abandoned the teleological point of view which he usually adopts in
Biology.
Directly after the admirable passage which I have just quoted, there
follows a remark which completely takes off its edge. After having quite
correctly maintained the origin of organic forms out of raw matter by
mechanical laws (in the manner of crystallization), as well as a gradual
development of the different species by descent from one common original
parent, Kant adds, “But he (the archæologist of nature, that is the
palæontologist) must for this end ascribe to the common mother an
organization ordained purposely with a view to the needs of all her
offspring, otherwise the possibility of suitability of form in the
products of the animal and vegetable kingdoms (_i.e._ teleological
adaptation) cannot be conceived at all.” This addition clearly
contradicts the most important fundamental thought of the preceding
passage, viz., that a purely mechanical explanation of organic nature
becomes possible through the Theory of Descent. And that the
teleological conception of organic nature predominated with Kant, is
shown by the heading of the remarkable § 79, which contains the two
contradictory passages cited: “_Of the Necessary Subordination of the
Mechanical to the Teleological Principle, in the explanation of a thing
as a purpose or object of Nature._”
He expresses himself most decidedly against the mechanical explanation
of organic nature in the following passage (§ 74): “It is quite certain
that we cannot become sufficiently acquainted with organized creatures
and their hidden potentialities by aid of purely mechanical natural
principles, much less can we explain them; and this is so certain, that
we may boldly assert that it is absurd for man even to conceive such an
idea, or to hope that a Newton may one day arise able to make the
production of a blade of grass comprehensible, according to natural laws
ordained by no intention; such an insight we must absolutely deny to
man.” Now, however, this impossible Newton has really appeared seventy
years later in Darwin, whose Theory of Selection has actually solved the
problem, the solution of which Kant had considered absolutely
inconceivable!
In connection with Kant and the German philosophers whose theories of
development have already occupied us in the preceding chapter, it seems
justifiable to consider briefly some other German naturalists and
philosophers, who, in the course of our century, have more or less
distinctly resisted the prevailing teleological views of creation, and
vindicated the mechanical conception of things which is the basis of the
Doctrine of Filiation. Sometimes general philosophical considerations,
sometimes special empirical observations, were the motives which led
these thinking men to form the idea that the various individual species
of organisms must have originated from common primary forms. Among them
I must first mention the great German geologist, Leopold Buch. Important
observations as to the geographical distribution of plants led him to
the following remarkable assertion in his excellent “Physical
Description of the Canary Islands”:—
“The individuals of genera, on continents, spread and widely diffuse
themselves, and by the difference of localities, nourishment, and soil,
form varieties; and being in consequence of their isolation never
crossed by other varieties, and so brought back to the main type, they
in the end become a permanent and a distinct species. Then, perhaps, in
other ways, they once more become associated with other descendants of
the original form—which have likewise become new varieties—and both
now appear as very distinct species, no longer mingling with one
another. Not so on islands. Being commonly confined in narrow valleys or
within the limit of small zones, individuals can reach one another and
destroy every commencing production of a permanent variety. Much in the
same way the peculiarities or faults in language, originating with the
head of some family, become, through the extension of the family,
indigenous throughout a whole district. If the district is separated and
isolated, and if the language is not brought back to its former purity
by constant connection with that spoken in neighbouring districts, a
dialect will be the result. If natural obstacles, forests, constitution,
form of government, unite the inhabitants of the separate district still
more closely, and separate them still more completely from their
neighbours, the dialect is fixed, and becomes a completely distinct
language.” (Uebersicht der Flora auf den Canarien, S. 133.)
We perceive that Buch is here led to the fundamental idea of the Theory
of Descent by the phenomena of the geography of plants, a department of
biological knowledge which in fact furnishes a mass of proofs in favour
of it. Darwin has minutely discussed these proofs in two separate
chapters of his book (the 11th and 12th). Buch’s remark is further of
interest, because it leads us to the exceedingly instructive comparison
of the different branches of language with the species of organisms, a
comparison which is of the greatest use to Comparative Philology, as
well as to Comparative Botany and Zoology. Just as, for example, the
different dialects, provincialisms, branches, and off-shoots of the
German, Slavonic, Greco-Latin, and Irano-Indian parent language, are
derived from a single common Indo-Germanic parent tongue, and just as
their _differences_ are explained by _Adaptation_, and their common
_fundamental characters_ explained by _Inheritance_, so in like manner
the different species, genera, families, orders, and classes of
Vertebrate animals are derived from a single common vertebrate form of
animal. Here also Adaptation is the cause of differences, Inheritance
the cause of community of character. This interesting parallelism in the
divergent development of the forms of speech and the forms of organisms
has been discussed in the clearest manner by one of our first
comparative philologists, the talented Augustus Schleicher, whose
premature death, four years ago, remains an irreparable loss, not only
to our University of Jena, but to the whole of monistic science.(6)
Among other eminent German naturalists who have expressed their belief
in the Theory of Descent more or less distinctly, arriving at their
conclusion in very various ways, I must next mention Carl Ernst Bär,
the great reformer of animal embryology. In a lecture delivered in 1834,
entitled “The Most General Laws of Nature in All Development,” he shows,
in the clearest way, that only in a very childish view of nature could
organic species be regarded as permanent and unchangeable types, and
that really they can be only passing series of generations, which have
developed by transformation from a common original form. The same
conception again received firm support from Baer, in 1859, through a
consideration of the laws of the geographical distribution of organisms.
J. M. Schleiden, who founded, thirty years ago, in Jena, a new epoch in
Botany by his strictly empirico-philosophical and truly scientific
method, illustrated the philosophical significance of the conception of
organic species in his incisive “Outlines of Scientific Botany,”(7) and
showed that it had only a subjective origin in the general _law of
specification_. The different species of plants are only the specified
productions of the formative tendencies of plants, which arise from the
various combinations of the fundamental forces of organic matter.
The eminent botanist, F. Unger, of Vienna, was led by his profound and
comprehensive investigations on extinct vegetable species, to a
palæontological history of the development of the vegetable kingdom,
which distinctly asserts the principle of the Theory of Descent. In his
“Attempt at a History of the World of Plants” (1852), he maintains the
derivation of all different species of plants from a few primary forms,
and perhaps from a single original plant, a simple vegetable cell. He
shows that this view is founded on the genetic connection of all
vegetable forms, and is necessary, not merely upon philosophical
grounds, but upon those of experience and observation.(8)
Victor Carus, of Leipzig, in the Introduction to his excellent “System
of Animal Morphology,”(9) published in 1853, in which he endeavours to
establish in a philosophical manner the universal constructive laws of
the animal body through comparative anatomy and the history of
development, makes the following remark:—“The organisms buried in the
most ancient geological strata must be looked upon as the ancestors from
whom the rich diversity of forms of the present creation have originated
by continued generation, and by accommodation to progressive and very
different conditions of life.”
In the same year (1853) Schaaffhausen, the anthropologist of Bonn, in an
Essay “On the Permanence and Transformation of Species,” declared
himself decidedly in favour of the Theory of Descent. According to him,
the living species of animals and plants are the transformed descendants
of extinct species, from which they have arisen by gradual modification.
The divergence or separation of the most nearly allied species takes
place by the destruction of the connecting intermediate stages.
Schaaffhausen also maintained, with distinctness, the origin of the
human race from animals, and its gradual development from ape-like
animals, the most important deduction from the Doctrine of Filiation.
Lastly, we have still to mention among the German Nature-philosophers
the name of Louis Büchner, who, in his celebrated work, “Force and
Matter” (1855), also independently developed the principles of the
Theory of Descent, taking his stand mainly on the ground of the
undeniable evidences of fact which are furnished by the palæontological
and individual development of organisms, as well as by their
comparative anatomy and by the parallelism of these series of
development. Büchner showed very clearly that, even from such data
alone, the derivation of the different organic species from common
primary forms followed as a necessary conclusion, and that the origin of
these original primary forms could only be conceived of as the result of
a spontaneous generation.
We now turn from the German to the French Nature-philosophers, who have
likewise held the Theory of Descent, since the beginning of the present
century. At their head stands Jean Lamarck, who occupies the first place
next to Darwin and Goethe in the history of the Doctrine of Filiation.
To him will always belong the immortal glory of having for the first
time worked out the Theory of Descent, as an independent scientific
theory of the first order, and as the philosophical foundation of the
whole science of Biology. Although Lamarck was born as early as 1744, he
did not begin the publication of his theory until the commencement of
the present century, in 1801, and established it more fully only in
1809, in his classic “Philosophie Zoologique.”(2) This admirable work is
the first connected exposition of the Theory of Descent carried out
strictly into all its consequences. By its purely mechanical method of
viewing organic nature, and the strictly philosophical proofs brought
forward in it, Lamarck’s work is raised far above the prevailing
dualistic views of his time; and with the exception of Darwin’s work,
which appeared just half a century later, we know of none which we could
in this respect place by the side of the “Philosophie Zoologique.” How
far it was in advance of its time is perhaps best seen from the
circumstance that it was not understood by most men, and for fifty
years was not spoken of at all. Cuvier, Lamarck’s greatest opponent, in
his “Report on the Progress of Natural Sciences,” in which the most
unimportant anatomical investigations are enumerated, does not devote a
single word to this work, which forms an epoch in science. Goethe, also,
who took such a lively interest in the French nature-philosophy and in
“the thoughts of kindred minds beyond the Rhine,” nowhere mentions
Lamarck, and does not seem to have known the “Philosophie Zoologique” at
all. The great reputation which Lamarck gained as a naturalist he does
not owe to his highly important general work, but to numerous special
treatises on the lower animals, particularly on Molluscs, as well as to
an excellent “Natural History of Invertebrate Animals,” which appeared,
in seven volumes, between the years 1815-1822. The first volume of this
celebrated work contains in the general introduction a detailed
exposition of his theory of filiation. I can, perhaps, give no better
idea of the extraordinary importance of the “Philosophie Zoologique”
than by quoting _verbatim_ some of the most important passages
therefrom:—
“The systematic divisions of classes, orders, families, genera, and
species, as well as their designations, are the arbitrary and artificial
productions of man. The kinds or species of organisms are of unequal
age, developed one after the other, and show only a relative and
temporary persistence; species arise out of varieties. The differences
in the conditions of life have a modifying influence on the
organization, the general form, and the parts of animals, and so has the
use or disuse of organs. In the first beginning only the very simplest
and lowest animals and plants came into existence; those of a more
complex organization only at a later period. The course of the earth’s
development, and that of its organic inhabitants, was continuous, not
interrupted by violent revolutions. Life is purely a physical
phenomenon. All the phenomena of life depend on mechanical, physical,
and chemical causes, which are inherent in the nature of matter itself.
The simplest animals and the simplest plants, which stand at the lowest
point in the scale of organization, have originated and still originate
by spontaneous generation. All animate natural bodies or organisms are
subject to the same laws as inanimate natural bodies or anorgana. The
ideas and actions of the understanding are the motional phenomena of the
central nervous system. The will is in truth never free. Reason is only
a higher degree of development and combination of judgments.”
These are indeed astonishingly bold, grand, and far-reaching views, and
were expressed by Lamarck sixty years ago; in fact, at a time when their
establishment, by a mass of facts, was not nearly as possible as it is
in our day. Indeed Lamarck’s work is really a complete and strictly
monistic (mechanical) system of nature, and all the important general
principles of monistic Biology are already enunciated by him: the unity
of the active causes in organic and inorganic nature; the ultimate
explanation of these causes in the chemical and physical properties of
matter itself; the absence of a special vital power, or of an organic
final cause; the derivation of all organisms from some few, most simple
original forms, which have come into existence by spontaneous generation
out of inorganic matter; the coherent course of the whole earth’s
history; the absence of violent cataclysmic revolutions; and in general
the inconceivableness of any miracle, of any supernatural interference,
in the natural course of the development of matter.
The fact that Lamarck’s wonderful intellectual feat met with scarcely
any recognition, arises partly from the immense length of the gigantic
stride with which he had advanced beyond the next fifty years, partly
from its defective empirical foundation, and from the somewhat one-sided
character of some of his arguments. Lamarck quite correctly recognizes
_Adaptation_ as the first mechanical cause which effects the continual
transformation of organic forms, while he traces with equal justice the
similarity in form of different species, genera, families, etc., to
their blood-relationship, and thus explains it by _Inheritance_.
Adaptation, according to him, consists in this, that the perpetual, slow
change of the outer world causes a corresponding change in the actions
of organisms, and thereby also causes a further change in their forms.
He lays the greatest stress upon the effect of _habit_ upon the use and
disuse of organs. This is certainly of great importance in the
transformation of organic forms, as we shall see later. However, the way
in which Lamarck wished to explain exclusively, or at any rate mainly,
the change of forms, is after all in most cases not possible. He says,
for example, that the long neck of the giraffe has arisen from its
constantly stretching out its neck at high trees, and from the endeavour
to pick the leaves off their branches; as giraffes generally inhabit dry
districts, where only the foliage of trees afford them nourishment, they
were forced to this action. In like manner the long tongues of
wood-peckers, humming-birds, and ant-eaters, are said by him to have
arisen from the habit of fetching their food out of narrow, small, and
deep crevices or channels. The webs between the toes of the webbed feet
in frogs and other aquatic animals have arisen solely from the constant
endeavour to swim, from striking their feet against the water, and from
the very movements of swimming. Inheritance fixed these habits on the
descendants, and finally, by further elaboration, the organs were
entirely transformed. However correct, as a whole, this fundamental
thought may be, yet Lamarck lays the stress too exclusively on _habit_
(use and non-use of organs), certainly one of the most important, but
not the only cause of the change of forms. Still this cannot prevent our
acknowledging that Lamarck quite correctly appreciated the mutual
co-operation of the two organic formative tendencies of Adaptation and
Inheritance. What he failed to grasp is the exceedingly important
principle of “Natural Selection in the Struggle for Existence,” with
which Darwin, fifty years later, made us acquainted.
It still remains to be mentioned as a special merit of Lamarck, that he
endeavoured to prove the _development of the human race_ from other
primitive, ape-like mammals. Here again it was, above all, to habit that
he ascribed the transforming, the ennobling influence. He assumed that
the lowest, original men had originated out of men-like apes, by the
latter accustoming themselves to walk upright. The raising of the body,
the constant effort to keep upright, in the first place led to a
transformation of the limbs, to a stronger differentiation or separation
of the fore and hinder extremities, which is justly considered one of
the most essential distinctions between man and the ape. Behind, the
calf of the leg and the flat soles of the feet were developed; in
front, the arms and hands, for the purpose of seizing objects. The
upright walk was then followed by a freer view over the surrounding
objects, and led consequently to an important progress in mental
development. Human apes thereby soon gained a great advantage over the
other apes, and further, over surrounding organisms in general. In order
to maintain the supremacy over them, they formed themselves into
companies, and there arose, as in the case of all animals living in
company, the desire of communicating to one another their desires and
thoughts. Thus arose the necessity of language, which, consisting at
first of rough and disjointed sounds, soon became more connected,
developed, and articulate. The development of articulate speech now in
turn became the strongest lever for a further progressive development of
the organism, and above all, of the brain, and so ape-like men became
gradually and slowly transformed into real men. In this way the actual
descent of the lowest and rudest primitive men from the most highly
developed apes was distinctly maintained by Lamarck, and supported by a
series of the most important proofs.
The honour of being the chief French nature-philosopher is not usually
assigned to Lamarck, but to Etienne Geoffroy St. Hilaire (the elder),
born in 1771, the same in whom Goethe was especially interested, and
with whom we have already become acquainted as Cuvier’s most prominent
opponent. He developed his ideas about the transformation of organic
species as far back as the end of the last century, but published them
only in the year 1828, and then in the following years, especially in
1830, defended them bravely against Cuvier. Geoffroy St. Hilaire in all
essentials adopted Lamarck’s Theory of Descent, yet he believed that
the transformation of animal and vegetable species was less effected by
the action of the organism itself (by habit, practice, use, or disuse of
organs) than by the “monde ambiant,” that is, by the continual change of
the outer world, especially of the atmosphere. He conceives the organism
as passive, in regard to the vital conditions of the outer world, while
Lamarck, on the contrary, regards it as active. Geoffroy thinks, for
example, that birds originated from lizard-like reptiles, simply by a
diminution of the carbonic acid in the atmosphere, in consequence of
which the breathing process became more animated and energetic through
the increased proportion of oxygen in the atmosphere. Thus there arose a
higher temperature of the blood, an increased activity of the nerves and
muscles, and the scales of the reptiles became the feathers of the
birds, etc. This conception is based upon a correct thought, but
although the change of the atmosphere, as well as the change of every
other external condition of existence, certainly effects directly or
indirectly the transformation of the organism, yet this single cause is
by itself too unimportant for such effects to be ascribed to it. It is
even less important than practice and habit, upon which Lamarck lays too
much stress. Geoffroy’s chief merit consists in his having vindicated
the monistic conception of nature, the unity of organic forms, and the
deep genealogical connection of the different organic types in the face
of Cuvier’s powerful influence. I have already mentioned in the
preceding chapter (pp. 87, 88) the celebrated disputes between the two
great opponents in the Academy of Paris, especially the fierce conflicts
on the 22nd of February, and on the 19th of July, in which Goethe took
so lively an interest. On that occasion Cuvier remained the
acknowledged victor, and since that time very little, or rather nothing,
more has been done in France to further the development of the Doctrine
of Filiation, and complete the monistic theory of development. This is
evidently to be ascribed principally to the repressive influence
exercised by Cuvier’s great authority. Even at the present day the
majority of the French naturalists are the disciples and blind followers
of Cuvier. In no civilized country of Europe has Darwin’s doctrine had
so little effect and been so little understood as in France, so that in
the further course of our examination we need not take the French
naturalists into consideration. At most, there are two distinguished
botanists, among the recent French naturalists, whom we may mention as
having ventured to express themselves in favour of the mutability and
transformation of species. These two men are Naudin (1852) and Lecoq
(1854).
Having discussed the early services of German and French
nature-philosophy in establishing the doctrine of descent, we turn to
the third great country of Europe, to free England, which during the
last ten years has become the chief seat and starting-point for the
further working out and definite establishment of the theory of
development. Englishmen, who now take such an active part in every great
scientific progress of humanity, and are the first to promote the
eternal truths of natural science, at the beginning of the century took
but little part in the continental nature-philosophy and its most
important progress, the Theory of Descent. Almost the only earlier
English naturalist whom we have here to mention is Erasmus Darwin, the
grandfather of the reformer of the Theory of Descent. In 1795 he
published, under the title of “Zoonomia,” a scientific work in which he
expresses views very similar to those of Goethe and Lamarck, without,
however, then knowing anything about these two men. It is evident that
the Theory of Descent at that time pervaded the intellectual atmosphere.
Erasmus Darwin lays great stress upon the transformation of animal and
vegetable species by their own vital action and by their becoming
accustomed to changed conditions of existence, etc. Next, W. Herbert, in
1822, expressed the opinion that species of animals and plants are
nothing but varieties which have become permanent. In like manner Grant,
in Edinburgh, in 1826, declared that new species proceed from existing
species by continued transformation. In 1841 Freke maintained that all
organic beings must be descended from a single primitive type. In 1852
Herbert Spencer demonstrated minutely, and in a very clear and
philosophic manner, the necessity of the Doctrine of Filiation, and
established it more firmly in his excellent “Essays,” which appeared in
1858, and in his “Principles of Biology,” which was published at a later
date. He has, at the same time, the great merit of having applied the
theory of development to psychology, and of having shown that the
emotional and intellectual faculties could only have been acquired by
degrees and developed gradually. Lastly, we have to mention that in 1859
Huxley, the first of English zoologists, spoke of the Theory of Descent
as the only hypothesis of creation reconcilable with scientific
physiology. The same year produced the “Introduction to the Flora of
Tasmania,” in which Hooker, the celebrated English botanist, adopts the
Theory of Descent, supporting it with important observations of his
own.
All the naturalists and philosophers with whom we have become acquainted
in this brief historical survey, as men adopting the Theory of
Development, merely arrived at the conception that all the different
species of animals and plants which at any time have lived, and still
live, upon the earth, are the gradually changed and transformed
descendants of one or some few original and very simple prototypes,
which latter arose out of inorganic matter by spontaneous generation.
But none of them succeeded in placing this fundamental element of the
doctrine of descent in relation with some cause, nor in satisfactorily
explaining the transformation of organic species by the true
demonstration of its mechanical antecedents. Charles Darwin was the
first who solved this most difficult problem, and this forms the broad
gulf which separates him from his predecessors.
The special merit of Charles Darwin is, in my opinion, twofold: in the
first place, the doctrine of descent, the fundamental idea of which was
already clearly expressed by Goethe and Lamarck, has been developed by
him much more comprehensively, has been traced much more minutely in all
directions, and carried out much more strictly and connectedly than by
any of his predecessors; and secondly, he has established a new theory,
which reveals to us the natural causes of organic development, the
acting causes (causæ efficientes) of organic form-production, and of the
changes and transformations of animal and vegetable species. This is the
theory which we call the Theory of Selection, or more accurately, the
Theory of Natural Selection (selectio naturalis).
When we reflect that (with the few exceptions above mentioned) the
whole science of Biology, before Darwin’s time, was elaborated in
accordance with the opposite views, and that almost all zoologists and
botanists regarded the absolute independence of organic species as a
self-evident inference from the results of all study of forms, we shall
certainly not lightly value the twofold merit of Darwin. The false
doctrine of the constancy and independent creation of individual species
had gained such high authority, was so generally recognized, and was,
moreover, so much favoured by delusive appearances, accepted by
superficial observation, that, indeed, no small degree of courage,
strength, and intelligence was required to rise as a reformer against
its omnipotence, and to dash to pieces the structure artificially
erected upon it. But, in addition to this, Darwin added to Lamarck’s and
Goethe’s doctrine of descent the new and highly important principle of
“natural selection.”
We must sharply distinguish the two points—though this is usually not
done—first, Lamarck’s Theory of Descent, which only asserts _that_ all
animal and vegetable species are descended from common, most simple, and
spontaneously generated prototypes; and secondly, Darwin’s Theory of
Selection, which shows us _why_ this progressive transformation of
organic forms took place, and what causes, acting mechanically, effected
the uninterrupted production of new forms, and the ever increasing
variety of animals and plants.
Darwin’s immortal merit cannot be justly estimated until a later period,
when the Theory of Development, after overthrowing all other theories of
creation, will be recognized as the supreme principle of explanation in
Anthropology, and, consequently, in all other sciences. At present,
while in the hot contest for truth the name of Darwin is the watchword
to the advocates of the natural theory of development, his merits are
inaccurately appreciated on both sides, for some persons overestimate
them as much as others underestimate them.
His merit is overestimated when he is regarded as the founder of the
Theory of Descent, or of the whole of the Theory of Development. We have
seen from the historical sketch in this and the preceding chapters, that
the Theory of Development, as such, is not new; all philosophers who
have refused to be led captive by the blind dogma of a supernatural
creation, have been compelled to assume a natural development. But the
Theory of Descent constituting the specially biological part of the
universal Theory of Development, had already been so clearly expressed
by Lamarck, and carried out so fully by him to its most important
consequences, that we must honour him as the real founder of it. Hence
it is only the Theory of Selection, and not that of Descent, which may
be called _Darwinism_; but this is in itself of so much importance, that
its value can scarcely be overestimated.
Darwin’s merit is naturally underestimated by all his opponents. But it
is scarcely possible in this matter to point to scientific opponents,
who are entitled by profound biological culture to pronounce an opinion.
For among all the works opposed to Darwin and the Theory of Descent yet
published, with the exception of that of Agassiz, not one deserves
consideration, much less refutation; all have so evidently been written
either without thorough knowledge of biological facts, or without a
clear philosophical understanding of the question in hand. We need not
trouble ourselves at all about the attacks of theologians and other
unscientific men, who really know nothing whatever of nature.
The only eminent scientific adversary who still remains opposed to
Darwin and the whole theory of development is Louis Agassiz; but the
principle of his opposition in reality deserves notice only as a
philosophical curiosity. In a French translation of his “Essay on
Classification,”(5) which we have spoken of before, published in Paris
in 1869, Agassiz has most formally announced his opposition to
Darwinism, which he had previously expressed in many ways. To this
translation he has appended a treatise of sixteen pages, bearing the
title, “Le Darwinisme. Classification de Haeckel.” This curious chapter
contains the most wonderful things; as, for example, “Darwin’s idea is a
conception _à priori_. Darwinism is a burlesque of facts. Science would
renounce the claim which it has hitherto possessed to the confidence of
earnest minds if such sketches were to be accepted as indications of a
true progress.” The following passage, however, is the climax of this
strange polemic: “Darwinism shuts out almost the whole mass of acquired
knowledge in order to retain and assimilate to itself that only which
may serve its doctrine.”
Surely this is what we may call turning the whole affair topsy-turvy!
The biologist who knows the facts must be astounded at Agassiz’s courage
in uttering such sentences—sentences without a word of truth in them,
and which he cannot himself believe! The impregnable strength of the
Theory of Descent lies just in the fact that all biological facts are
explicable only through it, and that without it they remain
unintelligible miracles. All our “laborious knowledge” in comparative
anatomy and physiology—in embryology and palæontology—in the doctrine
of the geographical and topographical distribution of organisms, etc.,
constitutes an irrefutable testimony to the truth of the Theory of
Descent.
In my General Morphology, especially in the sixth book (in the General
Phylogeny), I have minutely refuted Agassiz’s “Essay on Classification”
in all essential points. The twenty-fourth chapter I have devoted to a
very detailed and strictly scientific discussion of that section which
Agassiz himself considers the most important (the groups or categories
of systematic zoology and botany), and have shown that this part of his
work is purely chimerical, without any trace of real foundation. Agassiz
takes good care not to venture anywhere to touch upon my refutation,
because, forsooth, he is not in a position to produce anything
substantial against it. He fights not with arguments, but with phrases.
However, such opposition will not delay the complete victory of the
Theory of Development, but only accelerate it.