In one of the oldest biological treatises in the world, the soul
or life of an organism is defined in the most general way as an
activity of a natural organic living body--ἐντελέχεια σώματος φυσικου̑
ὀργανικου̑ δυνάμει ζωὴν ἔχοντος--life being autonomous nutrition and
growth and decay. The activity may, however, be latent or patent,
passive or active, sleeping or waking, without losing its peculiar
characters. It is substance (οὐσία), but substance as ‘form’ as opposed
to the material substance of the body, and the living body is therefore
also a substance in a double sense.
It is not identical with the body; but as form, proportion (λόγος),
activity (ἐνέργεια), essence (τὸ τί ἠν εἰναι), it is related
to the body, mere matter (ὕλη), and potentiality (δύναμις) in just
the same way as the seal is related to the wax; and the body is the
instrument whereby it effects its purposes; though subsequent in time,
it is prior in thought to the body, as all activities are to the
materials with which they operate.
At the same time neither it nor its parts are separable from the body,
with the exception, possibly, of mind (νου̑ς); it is indeed the actual
or possible functioning of the body, like the seeing of the eye or
the cutting of the axe, and with the disappearance of the capacity of
this functioning the soul itself also perishes. Lastly, it is a cause
(ἀρχὴ καὶ αἰτία) in a triple sense: first, as the source of motion;
secondly, as that for the sake of which the body exists; and thirdly,
as its essence (οὐσία) or formal cause. The soul or life is of several
kinds, which form together an ascending series each member of which is
necessarily involved in those above it.
The lowest is the nutritive soul (θρεπτική), found in all living
things, and the only soul possessed by plants. It is defined as motion
in respect of nutrition, decay, and growth, processes which involve
alteration (ἀλλοίωσις) in the body; and its functions (ἔργα) are to
utilize food for the maintenance and reproduction of the form of the
body, and to control and limit growth.
The second is the perceptive soul (αἰσθητική), the possession of
which distinguishes animals from plants. This also is a kind of
alteration (ἀλλοίωσις τίς) and consists in being moved and affected.
The fundamental and indispensable perception is touch (ἁφή), for it is
concerned in the acquisition of the food. It is invariably present: the
others may or may not, some or all, coexist with it.
Thirdly, some animals are possessed of a capacity for locomotion, and
the performance of this function requires again a special kind of soul.
Lastly, there is the reasoning soul (διανοητικά) or mind (νου̑ς). This
is found in man alone, unless there be other beings similar to him, or
even nobler than he. Mind alone is eternal and separable from the body.
Though the observation and experiment of modern science would doubtless
find much to alter in the details of these simple definitions, yet it
must be conceded that, by what is certainly a most fortunate guess if
it is not the most wonderful insight, Aristotle has laid his finger
on the cardinal point of modern physiological doctrine. For, putting
aside for the moment the mental faculties, it is here laid down in
the clearest manner that not only the functions of growth and decay,
nutrition, and reproduction, but also the capacity of responding to
stimuli are to be ultimately resolved into some kind of movement of the
particles of which the body is composed. Life, in short, as we might
say with Virchow, is a mode of motion.
The biology of to-day distinguishes living from inanimate bodies by the
possession and exercise of the three principal properties or functions
of metabolism, irritability, and reproduction; and further, the body
which performs these functions is not only composed of chemically
complex substances--proteids--which are not found in things that are
not alive, but possesses a structure. In no case, even the simplest, is
the organism a mere homogeneous lump of protoplasm, but it has parts or
organs, visibly different from one another, and obviously correlated
with the activities appropriated to each; and it is the preservation
of that structure, in the individual and in the race, which is the end
towards which the collective performance of all these functions, or the
life of the organism, is apparently directed.
Some of these peculiarities are shared by certain things that are
not commonly regarded as alive. Crystals have of course a definite
structure; they can divide, and when broken they can make good the
missing part, but they do not assimilate to the substance of their own
bodies a food-material which is less complex than it, and they are not
irritable.
The differences, indeed, between the living and the lifeless are so
profound, that it is not to be wondered at that there should have been
in all ages natural philosophers who have held that living activities
are phenomena _sui generis_, differing _toto caelo_ from the properties
exhibited by lifeless bodies, and never by any conceivability to be
expressed in terms of these.
This doctrine is vitalism.
It exists in several varieties, but one at least is of very ancient
lineage and can be traced back through mediaeval times to the
biological speculations of the Greeks.
Whether Aristotle really held the vitalistic views which have since
been attributed to him is a matter we shall have to discuss later on,
but it is certain that in the writings of Galen there is to be found
a theory of life which bears the stamp of Aristotelian influence, and
was destined to hand that influence on to future generations. Galen
admits the sensitive soul of Aristotle as the peculiarity of animals,
and the rational soul for man, but substitutes for the nutritive soul
certain works of nature--attraction, repulsion, retention, alteration.
And further, the rational soul is no longer immortal, but perishable,
and is dependent on the body, where its seat is in the brain; it is
material or quasi-material, a πνευμα, most efficient when dry.
After a long interval this doctrine reappears in the sixteenth century
in the writings of Vesalius, who tells us that the heart has a vital
soul, the liver a natural soul, while there is elaborated in the
ventricles of the brain an animal spirit or principal soul.
Meanwhile, however, the conception of life as something material had
been discarded by Paracelsus for the belief that the soul, or as he
called it, the ‘Archaeus’, by which the chemical processes of the body
are governed, is not a material but a spiritual force, a view restated
by Stahl more than a hundred years afterwards. ‘The events of the
body’, says this author, ‘may be rough-hewn by chemical and physical
forces, but the soul will shape them to its own ends, and will do that
by its instrument, motion.’
This, of course, is vitalism, and vitalism in its extreme or
‘animistic’ form. The idea recurs later on in the biology of
Treviranus. To be living is to have a soul, he tells us, and the
conscious _Lebenskraft_ employs the forces of the material world to
form the organism. ‘Das Weitzenkorn hat allerdings Bewusstsein dessen,
was in ihm ist und aus ihm werden kann, und träumt wirklich davon.’
Though he adds quaintly enough, ‘Sein Bewusstsein und seine Träume
mögen dunkel genug sein’. It is curious to observe the revival, at the
beginning of the twentieth century, of this mediaeval mysticism in the
speculative writings of so accomplished an experimentalist as Hans
Driesch.
Driesch is an embryologist who in his earlier days had enunciated an
invaluable analytical theory of development, a theory which suggests
that while the formation of the first or elementary organs that
appear in the embryo or larva--such structures as the larval gut or
sense-organ, or the germ-layers--depends upon the presence in the germ
of certain specific organ-forming substances (and this is a fact which
has since been abundantly demonstrated by experiment), the origin of
parts that appear later in development may be accounted for by the
action of the first-formed structures upon one another, these actions
being in the nature of physiological responses to stimuli; and for this
also some evidence has been produced. On this view differentiation is a
mechanical process, set in motion by fertilization or some other cause,
and, given a certain initial structure of the germ or ovum, given the
presence in it of a certain number of parts or substances capable
of acting upon one another with a fixed co-ordination or harmony of
the stimuli and the responses, given further a proper constitution
of the external environment, then a definite result must follow, the
production of an organism which is like the parents that gave it birth.
But in his later treatises this hypothesis has been repudiated, and, by
a remarkable _volte-face_, replaced by a dogma of a wholly different
kind. For now it is urged that no merely material factors can possibly
account either for the harmony of development--the due co-ordination
of mutually reacting parts; or for the secondary harmony of
composition--the formation of complex organs by the union of tissues;
or for the functional harmony seen in the activities of the adult.
For example, it is asserted that any fragment of an egg of a
sea-urchin, if not too small (not less than 1/32 of the egg), can give
rise to a whole and normal larva. We are told that the cells of the
segmented ovum may be disarranged to any extent by various means,
such as raising the temperature, diluting the sea-water, removing the
calcium from the sea-water, or by shaking, without prejudice to the
ultimate normality of development. Each part of the ovum can therefore,
according to the needs of the case, give rise to any part of the
resulting organism. ‘Jeder Teil kann nach Bedürfniss jedes.’
And thirdly, when the gastrula of a sea-urchin is transversely divided
into two, each half, it is stated, develops into a diminished whole
larva in which the gut becomes divided into the characteristic three
regions, and all the other organs are formed in correct proportion.
For each of these acts of development in the whole uninjured larva an
explanation may conceivably be given in terms of formative stimuli
exerted by the originally distinct parts of the egg and calling forth
responses in other parts. A mechanism may be thought of which, when
set in motion, will achieve a certain end in accordance with its own
pre-established harmony; but a mechanism which can be subdivided _ad
libitum_, or almost _ad libitum_, and the parts of which will still
achieve the same end, will still behave as wholes with their parts
co-ordinated in the same ratio, temporally and spatially! Such a
mechanism is inconceivable; for to ensure the uniform result, the
relative amounts and positions of the necessary substances must be
imagined as identical in every possible fragment of the egg that
is not too small. Something is therefore required to superintend,
to co-ordinate the causes of development in the case not only of
the part but of the whole egg as well; and this something is not
material. A corroborative proof of the inadequacy of the purely
material explanation--the causal explanation in the ordinary sense
of the phrase--may be derived from a consideration of certain other
vital processes. The facts of acclimatization and immunity betray
an extraordinary adaptability of the organism to a change in its
environment; an organ will adapt itself structurally to an alteration,
quantitative or qualitative, of function [Roux’s ‘Functional
Adaptation’]; lost parts can be regenerated; and then there is the
physiology of the nervous system.
In all these cases of ‘regulation’--and indeed in all other responses
to stimuli--the same element, inexplicable in chemical and physical
terms, exists and must exist in development. This entity is not a
form of energy, but a vital constant, analogous to the constants
or ultimate conceptions of mechanics and physics and chemistry and
crystallography, but not reducible to these, just as these cannot be
translated into one another.
Driesch describes it as a rudimentary feeling and willing, a
‘psychoid’, ‘morphaesthetic’ or perceptive of that form which is the
desired end towards which it controls and directs all the material
elements of differentiation, like the grain of wheat of Treviranus,
dreaming dimly of its destiny. It is thus a _vera causa_--an
unconditional and invariable antecedent--a psychical factor which can
intervene in the purely physical series of causes and effects, and for
it he revives the Aristotelian term ‘Entelechy’.
Such is the ‘vitalism’ introduced by Hans Driesch, a teleological
theory clearly, but no mere metaphysical doctrine of final causes:
rather a dynamic teleology which not only sees an end in every organic
process, but postulates an immaterial entity to guide the merely
mechanical forces towards the realization of that end.
Such a theory is open to very serious criticism from both the
scientific and the philosophical side. But before we pass to that
criticism let us turn aside to examine some of the other aspects under
which the Proteus of Vitalism presents himself.
Thus the modern physiologist Bunge, while owning that it would be a
lack of intelligence to expect to make with our senses discoveries in
living nature of a different order to those revealed to us in inorganic
nature, yet insists that we must transfer to the objects of our sensory
perception, to the organs, to the tissue elements, and to every minute
cell, something which we have acquired from our own consciousness,
something, that is to say, which is not motion, and is not in space,
but is in time only.
The essence of vitalism, so Bunge would have it, lies in starting from
what we know, the internal world, to explain what we do not know,
the external world. We can only remark that this position appears
to rest upon an epistemological confusion, for Bunge has evidently
failed to distinguish between the idealism which teaches that the
world of nature, including our own bodies, only exists in so far as
it is an object of knowledge, that reality is ultimately ideal, and
the ‘animism’ which, as we have seen, gives every object, at least
every living object, in nature a directive consciousness of its own.
The former does not lie immediately within the scope of the present
inquiry; the latter we shall have occasion to discuss again.
How far the tenets of animism are to be attributed to Johannes Müller
is not very clear. For while Müller maintained that an organism is due
to an idea which regulates its structure, is the cause of its harmony,
and is in action in the organism itself, exerting on it a formative
power, yet he held that the process was unconscious. Müller indeed
distinguished explicitly between the vital and the mental or conscious
principle, for in the operations of the former the manifestation of
design is the result of necessity, not of choice. At the same time the
two resemble one another in being homogeneous, in existing throughout
the mass of the organism which they animate, and in being divided
together with the organism (as in regeneration) without suffering any
diminution or change of their powers.
In this conception of the unconscious idea there may possibly be some
confusion between the formal and the final cause, between the idea of
the end to be realized, present at the beginning in the mind of the
artificer, and the end itself. The former is animism: the latter is
sound enough as metaphysics, but is not science at all.
There is still another school of vitalists which, while not going so
far as to commit itself to a belief in a ‘psychoid’, yet proclaims
in no uncertain voice the autonomy of the organism, and not content
with the assertion that at present we have not succeeded in reducing
the activities of the organism to chemical, physical, and mechanical
processes, maintains the utter futility of such endeavour, and
pronounces over the hidden mysteries of life an eternal _Ignorabimus_.
Some such view as this we must, I think, attribute to Dr. Haldane. ‘In
biology’, he says, ‘the phenomena which are or ought to be observed
from the very beginning are not physical and chemical phenomena as
self-existent events, but these phenomena as expressions of the
activity of living organisms. It is the living organism, and not the
physical phenomenon, which is the reality for biology.’ His belief in
organic autonomy is based on the physiology of metabolism, secretion
and absorption, the circulation of the blood, and the nervous system.
Thus in discussing the blood, after pointing to the constancy in its
volume and composition, he proceeds: ‘Neither starvation nor ingestion
of food and drink materially affect it: liquid injected into it is got
rid of with remarkable rapidity; and any loss of blood by bleeding
is soon replaced. This vital metabolism of the circulatory system is
doubtless due chiefly to the activity of its lining endothelium, which
most certainly does not play the mere mechanical part which has often
been attributed to it. The other so-called “mechanisms” can likewise
be shown to have all the characteristics of the living body, inasmuch
as they actively maintain their structure, just as the organism as a
whole does so. There is thus no warrant for calling them mechanisms,
and thus ignoring what is one of their essential characteristics.’ In
passages such as these we seem to catch an echo of Müller’s unconscious
idea, and again we ask ourselves, Are we dealing with a final or a
formal cause? Indeed, Dr. Haldane insists that his ground conception is
teleological.
There is still one other vitalistic theory to which we must allude,
although its interest is now merely historical. This is the belief in
a special vital material, unlike the material of which lifeless bodies
are composed, and endowed with a special vital force, different from
but co-ordinate with the forces of mechanics and physics.
In his _Histoire Générale des Animaux_ Buffon, after referring to the
obvious peculiarities of animals and vegetables--that their actions are
directed to an end, the conservation of a durable species--proceeds
to elaborate a thesis in which it is held that they are composed
of organic germs, and that germs of the same kind are distributed
throughout nature, lifeless as well as living. When an animal or plant
dies, its body is dissolved into these germs, which are then scattered
abroad; when it assimilates, it is by separating these ubiquitous
particles from the brute inorganic portion of the food. The former is
utilized for its own growth, the latter it gets rid of by evacuation
and excretion. Lifeless matter is therefore never converted into living
material.
Another advocate of the doctrine of a vital force, a property of the
tissues of the body, and at perpetual war with those inorganic forms
which tend to their destruction, was the physiologist Bichat, Such
a conception as this could not of course survive the rise of modern
chemistry. Its death-knell was sounded when Lavoisier and Laplace
showed that the bodies of organisms were composed of the same elements
as are found in inanimate nature, and it has long since passed into the
limbo of discredited speculations.
Apart from this, vitalistic theories would appear to be in the main of
two kinds.
First, there is the metaphysical vitalism which tells us we can never
explain the living in terms of the lifeless, insists on the permanent
separation of the sciences of biology on the one hand from chemistry
and physics on the other, and preaches the autonomy of the organism
without venturing to tell us in what that autonomy consists.
Secondly, there is the psychological theory of animism which posits an
autonomous psychical entity to preside over the chemical and mechanical
operations of the body, whether already formed or in process of
development, and to direct them towards its own ends, the conservation
and reproduction of that body’s specific form.
A third party, halting between two opinions, suggests an unconscious
idea, without, however, clearly explaining whether this is to be taken
in a metaphysical or a psychological sense. Frankly opposed to vitalism
in all its forms is the conception of the living body as a mechanism.
This has also an honourable ancestry behind it. How far the biology
of Aristotle is to be looked upon as mechanistic we shall presently
have to inquire, but in Galen the soul is certainly material, or
quasi-material, as we have already observed. It is, however, in the
physiology of Descartes that mechanism first appears unmistakably in
its modern guise.
For Descartes the body is simply an earthly machine. The nerves are
tubes up which--in sensation--the animal spirits flow to the brain only
to be reflected (whence our term reflex action) down other tubes to the
muscles.
‘All the functions of the body’, he tells us, ‘follow naturally from
the sole disposition of its organs, just in the same way that the
movements of a clock or other self-acting machine or automaton follow
from the arrangement of its weights and wheels. So that there is no
reason on account of its functions to conceive that there exists in
the body any soul, whether vegetative or sensitive, or any principle
of movement other than the blood and its animal spirits agitated by
the heat of the fire which burns continually in the heart and does not
differ in nature from any of the other fires which are met with in
inanimate bodies.’
The rational soul, the soul which thinks, that is, understands, wishes,
imagines, remembers, and feels, is not material. Yet it always acts
through the machine, though that machine can go on perfectly well
without the soul. ‘When the body has all its organs properly arranged
for a particular movement it has no need of the soul to carry them out.
All movements, even those which we call voluntary, depend principally
on the same disposition of the organs. One and the same cause renders
the dead body unfit to produce the movements and leads the soul to quit
the body.’
The biology of Descartes appears to have been accepted by contemporary
physiologists like van Helmont and Borelli, and certainly commended
itself to another philosopher of eminence, Leibnitz. Like Descartes,
Leibnitz also affirms that the body is a machine or natural automaton;
unlike Descartes, however, he refuses to believe that the mind directs
the machine in any way. Rather there is a complete series of psychical
parallel to a complete series of physical events, and between the two a
pre-established harmony.
Although the details of Cartesian physiology have long since been
exploded, yet the mechanical principle which that philosophy enunciated
so clearly has persisted and has indeed proved to be the rock on
which modern physiological science has been built. For, when once the
chemists had discovered animal and plant structure to be composed of
elements found in lifeless bodies, and had proved that compounds found
only in the organism could yet be synthesized _in vitro_, there was
no longer any reason why the properties of the compounds should be
considered as of a different order to the properties of their component
elements. A method applicable to one was applicable to the other, and
as Claude Bernard has put it, mechanical, physical, and chemical forces
are the only effective agents in the living body, and they are the only
agencies of which the physiologist has to take account.
The substances of which the living body is made up are no doubt
extremely complex, yet none the less--to quote a more recent writer,
Verworn--‘physiology is in the last resort the chemistry of the
proteids’. This is the principle that has now for nearly a century
guided and stimulated research into the functions of the organism:
to this principle physiologists, too numerous to name, have not been
ashamed to subscribe: under its banner some of the proudest triumphs
of the science have been won. Yet it is precisely this which modern or
neo-vitalism has challenged and asks us to relinquish in favour of a
theory of psychoids or a pseudo-metaphysical view of life.
The vitalistic position may be assailed from two points, the scientific
and the philosophical.
In the first place the vitalist asserts that mechanism is inadequate
to explain the phenomena of metabolism, of transmission of nervous
stimuli, or of development. It is upon the last of these that Driesch
lays special stress.
He has urged, as we have seen, that although a mechanical explanation
might be given (such an explanation has indeed been put forward by
himself) of the specific differentiation of the organism by supposing
the first-formed elementary organs, developed out of the substances
given in the initial structure of the germ, to act and react upon one
another in accordance with a certain harmony, provided for by the same
structure; yet a mechanism which can be subdivided _ad libitum_ or
almost _ad libitum_, and each part of which will still give rise to a
complete organism, is not to be conceived. The answer to this objection
has, however, been supplied by the experiments of Driesch himself and
of many others. For though it is true that each of the first two, four,
eight, or even in some cases each of the first sixteen cells into which
the fertilized ovum becomes segmented, can, when separated from its
fellows, give rise to a complete organism, yet in all cases there comes
a time when the parts cease to be totipotent and produce not whole but
partial structures.
This invariable restriction of potentialities, which occurs earlier
in some cases than in others, and is not due to mere deficiency of
substance, is not hard to account for.
Those substances on the presence of which in the ovum, as experiment
has taught us, the formation of the elementary organs of the embryo or
larva depends, are arranged in different cases in different ways: and
they certainly may be, and very frequently are, so distributed that
while each of the first four cells contains a like quantity of each of
these specific substances, arranged in it exactly as they were in the
whole ovum, the next division will sunder these materials in such a way
that of the resulting eight blastomeres four will have more of one of
the primary egg-substances, less of another; the amounts apportioned
to the other four being in just the inverse ratio of this: and the
result will be a difference in the fate of the cells when they are
isolated from one another. In those of the one group the proportions of
the organs developed out of these substances will not be the same as
they are in the other. This is precisely the result which experiment
has revealed; it is exactly this result which Driesch has ignored, or
rather attempted to explain away.
It is evident, then, that to some extent the parts of this mechanism
are interchangeable, that it can be subdivided, and that each part,
brought now under new conditions, will still possess the potentialities
of the whole, just as such a mechanism as a rocket, out of which, under
the appropriate stimulus, a certain pattern of stars is developed,
might be subdivided into two or more rockets of half size or less.
There is, however, a limit to this interchangeability, while if the
subdivision be carried beyond a certain point the totipotence of the
parts is lost.
If the number of these organ-forming substances given in the germ were
very large, as large, let us suppose, as the total number of separately
inheritable characters, it might indeed be difficult to imagine a
mechanism divisible into even two totipotent parts. But from the need
for this assumption we are saved by the second part of Driesch’s own
_Analytische Theorie_, which accounts for subsequent processes of
differentiation by attributing the production of new parts to the
mutual interactions of those that are the first to appear. For this
also experimental evidence, though meagre, is not lacking, while a
close parallel is found in the dependence of certain bodily functions
upon substances--the hormones of Professor Starling--secreted by other
organs.
In the second place the vitalist maintains that the processes of
metabolism defy, nay more, always will defy, chemical and physical
analysis. The first part of this statement may be a true description
of the knowledge of to-day, but the existence in the living body of
the same elements as are met with elsewhere, the synthesis of complex
organic substances, the establishment of the equivalence of the energy
which leaves the body as mechanical work or heat to that which enters
it in chemical form in the food, should surely make us hesitate before
abandoning all hope of attaining to a chemistry of life.
And thirdly, there are physiologists who believe that the complex
phenomena presented to us in the activities of the nervous system are
susceptible of a purely mechanical explanation.
‘A feature’, says Gotch, ‘which more particularly suggests spontaneous
cellular activity is the well-known fact that centrifugal discharges
may continue after the obvious centripetal ones have ceased. This is
pre-eminently the case when the central mass is rendered extremely
unstable by certain chemical compounds, such as strychnine, &c. There
are, however, suggestive indications in connexion with such persistent
discharges. The more completely all the centripetal paths are blocked
by severance and other means, the less perceptible is such persistent
discharge, and since nervous impulses are continually streaming into
the central mass from all parts, even from those in apparent repose,
it would seem that could we completely isolate nerve-cells, their
discharge would probably altogether cease.’ Even in the hyper-excitable
condition produced by strychnine the spinal motor nerve cells do not
discharge centrifugal impulses when cut off from the centripetal
connexions. The physiologist, therefore, has ‘definite grounds for
believing that, as far as present knowledge goes, both the production
and cessation of central nervous discharges are the expression of
propagated changes and that these changes reveal themselves as
physico-chemical alterations of an electrolytic character. The nervous
process, which rightly seems to us so recondite, does not, in the light
of this conception, owe its physiological mystery to a new form of
energy, but to the circumstance that a mode of energy displayed in the
non-living world occurs in colloidal electrolytic structures of great
chemical complexity.’
To all these considerations we must add the fact that life did once
originate upon this planet from matter which was not alive, and that
even now some inorganic phenomena present at least remote analogies
with certain vital processes. Such are the structure, the spontaneous
division, and the regeneration of crystals.
We turn now to the philosophical objections that may be raised to
vitalistic speculations; and here we must be careful to distinguish
what we may term the psychological from the metaphysical form of the
theory.
Driesch has maintained that the belief in a morphaesthetic psychoid
finds support in the philosophies of Kant and Aristotle. Let us examine
the merits of this claim.
Like the scientists of to-day, Kant, in his _Critique of the
Teleological Judgement_, lays it down as a rule that the mechanical
method, by which natural phenomena are brought under general laws of
causation and so explained, should in all cases be pushed as far as
it will go, for this is a principle of the determinant judgement.
There are cases, however, in which this alone does not suffice. The
possibility of the growth and nutrition, above all of the reproduction
and regeneration of organisms, is only fully intelligible through
another quite distinct kind of causality, their purposiveness.
Organisms are not mere machines, for these have simply moving power.
Organisms possess in themselves formative power of a self-propagating
kind, which they communicate to their materials. They are, in fact,
natural purposes, both cause and effect of themselves, in which the
parts so combine that they are reciprocally both end and means,
existing not only by means of one another but for the sake of one
another and the whole. The whole is thus an end which determines the
process, a final cause which brings together the required matter,
modifies it, forms it, and puts it in its appropriate place. Such
purposiveness is internal, for the organism is at once its own cause
and an end to itself, not merely a means to other ends, like a machine
whose purposiveness is relative and whose cause is external.
Such is the principle of the teleological judgement. It is a heuristic
principle rightly brought to bear, at least problematically, upon the
investigation of organic nature, by a distant analogy with our own
causality according to purposes generally, and indispensable to us, as
anatomists, as a guiding thread if we wish to learn how to cognize the
constitution of organisms without aspiring to an investigation into
their first origin.
Could our cognitive faculties rest content with this maxim of the
reflective judgement it would be impossible for them to conceive of the
production of these things in any other fashion than by attributing
them to a cause working by design, to a Being which would be productive
in a way analogous to the causality of intelligence. Natural science,
however, needs not merely reflective but determinant principles
which alone can inform us of the possibility of finding the ultimate
explanation of the world of organisms in a causal combination for
which an understanding is not explicitly assumed, since the principle
of purposes does not make the mode of origination of organic beings
any more comprehensible. And then, in a passage remarkable for its
prophetic insight, Kant proceeds to show how this might be. This
‘analogy of forms’, he says, ‘which with all their difference seem to
have been produced according to a common original type, strengthens our
suspicion of an actual relationship between them in their production
from a common parent, through the gradual approximation of one genus to
another--from those in which the principle of purposes seems to be best
authenticated, that is from man down to the polype, and again from this
down to mosses and lichens, and finally to the lowest stage of nature
noticeable by us, namely, crude matter’. And so the whole technic of
nature, which is so incomprehensible to us in organized beings that
we believe ourselves compelled to think a different principle for it,
seems to be derived from matter and its powers according to mechanical
laws like those by which it operates in the formation of crystals. A
purposiveness must, however, be attributed even to the crude matter,
otherwise it would not be possible to think the purposive form of
animals and plants.
Although there are doubtless in the _Critique_ many obscurities and
inconsistencies, to which we cannot allude now, the general meaning
of Kant’s reflections upon organisms is perfectly clear. He who would
‘complete the perfect round’ of his knowledge must think not only
in beginnings but in ends. The end in the case of a living being is
apparently plain--it is the maintenance and reproduction of its form;
the end in the case of the cosmic process is to be sought in the
ethical, or, in Kantian phraseology, the ‘practical’ concept of the
freedom of the moral consciousness of man.
Such a position is quite intelligible, philosophically, but the
testimony it brings to the theory of the psychoid is of very doubtful
value, as Driesch is well aware. He complains indeed that Kant’s
teleology is descriptive or ‘static’, rather than ‘dynamic’, as is
perfectly true, except in the case of man, a point of which Driesch
naturally makes the most. There are, no doubt, passages where Kant
speaks of ‘a cause which brings together the required matter, modifies
it, forms it and puts it in its appropriate place’; but against these
must be set the explicit statement ‘that if the body has an alien
principle (the soul) in communion with it, the body must either be
the instrument of the soul--which does not make the soul a whit more
comprehensible--or be made by the soul, in which case it would not be
corporeal at all.’ Vitalism can glean small comfort from this. Let us
turn, then, to the second authority.
As we have seen already, the souls or functions of nutrition and
perception are, in the Aristotelian biology, ultimately to be expressed
as alterations or movements of the particles of the body; mind alone is
separable from body and eternal.
In the development of the individual organism the mind comes in from
outside, but the two souls of lower order are present in the σπέρμα, or
κύημα, as Aristotle calls it, which results from the commingling of the
male and female elements, or, as we should say, the fertilized ovum.
The material and efficient causes of development are not, however, both
contributed by each of the parents. ̑̑ The teaching of Aristotle is
that the matter is provided by the female and the female alone. The
egg (or catamenia in mammals) is described as being mere matter (ὕλη),
body (σω̑μα), potentiality (δύναμις), passive (παθητικόν) and merely
quantitative, although it is true that a sort of soul, the nutritive,
is somewhat grudgingly conceded to it, since unfertilized eggs appear
in some sense to be alive. The male element, on the other hand,
provides the principle of motion (ἀρχὴ τη̑ς κινήσεως) and the form
(εἰδος); it is qualitative, it is activity, it produces the perceptive
soul, if it is not itself that soul, and it is responsible for the
‘correct proportionality’ (λόγος) of the organization. The male element
contributes only motion, but no matter; it acts upon the female element
as rennet acts when it coagulates milk, except that the analogy is
incomplete, since the γονή brings about a qualitative and not merely
a quantitative change in the material on which it operates. To this
it imparts the same kind of motion which itself possesses, the motion
which was present in the particles of the food in its final form from
which it was itself derived. The communication of this motion is enough
to set going the machinery (αὐτόματον); the rest then follows of itself
in proper order.
Lastly, the sperm of the male acts like a cunning workman who makes a
work of art, using heat and cold as the workman uses his tools: for
this heat and this cold could never of themselves--by coagulations and
condensations--produce the form of the body as the older naturalists
had supposed, regarding only the efficient and ignoring the formal and
the final cause: for the organic body is not what it is because it is
produced in such and such a fashion, rather it is because it is to be
such and such that it must be developed as it is.
And here lies the kernel of the whole matter. For while Aristotle has
made it perfectly plain that, according to his idea, the soul, at
least its nutritive and perceptive faculties, is to be regarded as a
function of matter and that this function may be ultimately expressed
in terms of movement, and further that development is a mechanism
which is set going by the communication of motion proceeding from the
‘soul’ of the male element and derivable eventually from the motions
into which the ‘functions’ or ‘soul’ of the parent can be resolved to
the mere matter which the female provides, it is equally evident that
he does not regard this mechanical explanation--in terms of material
and efficient causes--as satisfactory or complete. But when we inquire
why, he gives us no certain nor consistent answer. On the one hand,
there are passages in which he tells us that there must be something
which controls the material forces and imposes on them a limit and
proportionality of growth; that the soul makes use of them as the
artist makes use of his implements, and such passages are naturally
interpreted by Driesch in the sense of a ‘dynamic’ teleology; it is the
ψυχή which superintends and controls, and the ψυχή is ‘entelechy’.
Elsewhere, however, we are informed that even the proportionality of
the developing parts is simply the outcome of the motion imparted by
the male, which is _actu_ what the female element only is _potentia_.
Moreover, it may be questioned whether Aristotle ever intended to
imply more than an ‘analogy with the causality of purpose’ when he
uses the figure of the workman and his implements to illustrate his
meaning of the formal cause. The formal cause of a work of art is an
intelligible _vera causa_; it is the idea in the mind of the artist
antecedent to the execution of the work; but the formal or final cause
of an organism, the end which it apparently strives to attain, can
only be said by a metaphor to be prior in time to the existence of the
organism itself. Prior in thought, however, it certainly is, for it
is only the performance of its functions (ἐντελέχεια) by the organism
complete in all its parts that makes the mere mechanism of development
comprehensible to us; the process, therefore, exists for the sake of
the end. Only as efficient cause is the soul prior in time; only so far
as it is prior in thought can it be said to be a final cause.
Such a teleology is, it is obvious, indistinguishable in principle from
the position in which Kant leaves us. It is the position adopted by
Driesch himself in his earlier _Analytische Theorie_, but abandoned in
the _Vitalismus_ in favour of a theory of ‘psychoids’.
Now quite apart from the meaning which Aristotle may or may not have
intended to convey, there are grave objections to this belief. This
‘psychoid’, to which the name ‘entelechy’ is surely misapplied, this
rudimentary feeling and willing, which is aware of the form it desires
to produce, must be psychically at least as complex as the phenomena it
is designed to account for, and stands, therefore, as much in need of
explanation as they; as Kant has observed, this will involve us at once
in an infinite series of such entities. In fact it is only a photograph
of the problem, and not a solution at all.
Again, when we ask what the _modus operandi_ of this cause is, we
get no reply either from Driesch or from any other neovitalist. The
objection that the intervention of a psychical cause in a physical
process is unintelligible, an objection which would probably appeal
to many, may be waived, for in the last resort the connexion between
any--even simple mechanical--causes and effects is equally hard to
understand.
It may, however, be doubted whether these entities are not being
multiplied beyond necessity, and whether the progress of science would
not be better served by an adherence to a simpler philosophy. But even
when it has discarded the psychoid we find vitalism still denying the
possibility of mechanical explanation, still preaching the autonomy of
the organism. The ‘dynamic’ teleology of Driesch has only disappeared
to be replaced by the metaphysical doctrine of the final cause.
We may point out, perhaps, in passing, that the organism is by no means
as autonomous as might be desired. The end towards which the creature
strives, the maintenance and reproduction of its own specific form,
is not a constant _terminus ad quem_, for species are as mortal as
individuals: nor is it always achieved; the autonomy of a worm, which,
bisected in a certain way, regenerates a tail instead of a head, or of
a frog, which, after a particular injury, develops six legs instead
of two, has surely renounced its rights. But, setting this aside, it
must be seriously questioned whether any good purpose is served in
biological discussion by decrying the value of mechanical conceptions
or by confounding two distinct orders of thought. The questions are
grave ones: for the issue at stake is no less than the existence of
physiology as the science of the causes of living activities.
‘Recte ponitur’, said Francis Bacon, ‘vere scire esse per causas
scire.’ The maxim of the great founder of modern inductive science has
been the lode-star of biology in the past, and is still its watchword
to-day. By exact observation and crucial experiment, utilizing every
canon of induction, the activities of the living organism are to
be brought under wide general laws of causation, which will be, in
the first instance, physiological laws--of response to stimuli, of
metabolism, and of growth: by means of these laws predictions can be
made, and verified as often as we please. But no bar can legitimately
be set to the scope of human inquiry; the thought process will not
rest here, and ultimately it may be possible to state the widest
generalizations of biology in chemical and physical, and these again in
purely mechanical terms. The maintenance and evolution of form in the
individual, as well as the larger evolution of form in the race, become
but the final terms in a far vaster cosmic process, from ‘homogeneity
to heterogeneity’.
The idea is, of course, perfectly familiar: it is the analysis of
purely physical causes, carried to its extreme limit. Phenomena are
thought out in terms not of origins merely, but of one origin, and that
one origin is the only mystery that remains. This unification of the
sciences has always been and must still remain the dream and the faith
and the inspiration of the scientific man, and could such an edifice
of the intellect ever be realized, the task of science would have been
completed. Only when this purely deterministic method has been pushed
as far as it will go does science leave off; only where science leaves
off does philosophy begin.
There is an order of time, and there is an order of thought. Science
works in the order of time, and necessarily so: for although science
can never say what constitutes the invariable link between antecedent
and consequent which it terms causal, yet it rightly speaks of the
first as cause, determining the second as effect, since it is its
function to predict from the past which is known to the future which is
not.
But the outlook of philosophy is different. Dissatisfied with the
endless regress of cause and effect, sceptical of first causes and
original homogeneities, out of which by no conceivability could any
heterogeneity have ever been developed, philosophy looks to the end.
The activities of living organisms at least appear to be directed to
an end; they are apparently purposive, and it is this purposiveness
which lends to biology, though built on the fundamental conceptions of
chemistry and physics, peculiar features of its own, and is, of course,
answerable for the teleological language which biologists so frequently
employ. And by a knowledge of the end, the view of science, to which
_qua_ science it cannot too rigidly confine itself, will doubtless be
supplemented and enlarged.
But, plain and definite though the end of an individual life may be,
the end of the race--of the human or any other race--the end of the
universe, are things only to be guessed at, and all we are left with is
an indefinite series of evolving systems emerging out of an infinite
past and fading into an infinite future.
In the final issue, indeed, the last effect is as delusive an _ignis
fatuus_ as the first cause. The philosophy which has rejected one must
divest itself of the other, and seek its end, if anywhere, in the
logical _prius_ of the mind, which, though last in time, is yet first
in thought, since through it alone can that ordered knowledge of nature
which we call science be born and brought to perfection.
[Illustration: From the Italian translation of ‘KETHAM’, VENICE 1493