NATURALISM

Sec. The meaning conveyed by any philosophical term consists largely of the distinctions which it suggests. Its peculiar quality, like the physiognomy of the battle-scarred veteran, is a composite of the controversies which it has survived. There is, therefore, an almost unavoidable confusion attendant upon the denomination of any early phase of philosophy as materialism. But in the historical beginnings of thought, as also in the common-sense of all ages, there is at any rate present a very essential strand of this theory. The naïve habit of mind which, in the sixth century before Christ, prompted successive Greek thinkers to define reality in terms of water, air, and fire, is in this respect one with that exhibited in Dr. Samuel Johnson’s smiting the ground with his stick in curt refutation of Bishop Berkeley’s idea-philosophy. There is a theoretical instinct, not accidental or perverse, but springing from the very life-preserving equipment of the organism, which attributes reality to tangible space-filling things encountered by the body. For obvious reasons of self-interest the organism is first of all endowed with a sense of contact, and the more delicate senses enter into its practical economy as means of anticipating or avoiding contact. From such practical expectations concerning the proximity of that which may press upon, injure, or displace the body, arise the first crude judgments of reality. And these are at the same time the nucleus of naïve philosophy and the germinal phase of materialism.

Sec. The first philosophical movement among the Greeks was a series of attempts to reduce the tangible world to unity, and of these the conception offered by Anaximander is of marked interest in its bearing upon the development of materialism. This philosopher is remarkable for having defined his first principle, instead of having chosen it from among the different elements already distinguished by common-sense. He thought the unity of nature to consist in its periodic evolution from and return into one infinite sum of material (+to apeiron+), which, much in the manner of the “nebula” of modern science, is conceived as both indeterminate in its actual state and infinitely rich in its potentiality. The conception of matter, the most familiar commonplace of science, begins to be recognizable. It has here reached the point of signifying a common substance for all tangible things, a substance that in its own general and omnipresent nature is without the special marks that distinguish these tangible things from one another. And in so far the philosophy of Anaximander is materialistic.

Sec. But the earliest thinkers are said to be hylozoists, rather than strict materialists, because of their failure to make certain distinctions in connection with the processes of matter. The term hylozoism unites with the conception of the formless material of the world (+hyle:+), that of an animating power to which its formations and transformations are due. Hylozoism itself was not a deliberate synthesis of these two conceptions, but a primitive practical tendency to universalize the conception, of life. Such “animism” instinctively associates with an object’s bulk and hardness a capacity for locomotion and general initiative. And the material principles defined by the philosophers retain this vague and comprehensive attribute as a matter of course, until it is distinguished and separated through attempts to understand it.

That aspect of natural process which was most impressive to Greek minds of the reflective type was the alternation of “generation and decay.” In full accord with his more ancient master, Epicurus, the Latin poet Lucretius writes:

“Thus neither can death-dealing motions keep the mastery always, nor entomb existence forevermore; nor, on the other hand, can the birth and increase giving motions of things preserve them always after they are born. Thus the war of first beginnings waged from eternity is carried on with dubious issue: now here, now there, the life-bringing elements of things get the mastery and are o’ermastered in turn: with the funeral wail blends the cry which babies raise when they enter the borders of light; and no night ever followed day, nor morning night, that heard not, mingling with the sickly infant’s cries, wailings of the attendants on death and black funeral."

In a similar vein, the earliest conceptions of natural evolution attributed it to the coworking of two principles, that of Love or union and that of Hate or dissolution. The process is here distinguished from the material of nature, but is still described in the language of practical life. A distinction between two aspects of vital phenomena is the next step. These may be regarded in respect either of the motion and change which attend them, or the rationality which informs them. Life is both effective and significant. Although neither of these ideas ever wholly ceases to be animistic, they may nevertheless be applied quite independently of one another. The one reduces the primitive animistic world to the lower end of its scale, the other construes it in terms of a purposive utility commensurable with that of human action. Now it is with mechanism, the former of these diverging ways, that the development of materialism is identified. For this philosophy a thing need have no value to justify its existence, nor any acting intelligence to which it may owe its origin. Its bulk and position are sufficient for its being, and the operation of forces capable of integrating, dividing, or moving it is sufficient for its derivation and history. In short, there is no rhyme or reason at the heart of things, but only actual matter distributed by sheer force. With this elimination of the element of purposiveness from the hylozoistic world, the content and process of nature are fitted to one another. Matter is that which is moved by force, and force is the determining principle of the motions of matter. Materialism is now definitely equipped with its fundamental conceptions.

Sec. The central conceptions of materialism as a philosophical theory differ from those employed in the physical sciences only in what is demanded of them. The scientist reports upon physical phenomena without accepting any further responsibility, while those who like Lucretius maintain a physical metaphysics, must, like him, prove that “the minute bodies of matter from everlasting continually uphold the sum of things.” But, though they employ them in their own way, materialists and all other exponents of naturalism derive their central conceptions from the physical sciences, and so reflect the historical development through which these sciences have passed. To certain historical phases of physical science, in so far as these bear directly upon the meaning of naturalism, we now turn.

Sec. From the earliest times down to the present day the groundwork of materialism has most commonly been cast in the form of an atomic theory. Democritus, the first system-builder of this school, adopted the conception of indivisible particles (+atomoi+), impenetrable in their occupancy of space, and varying among themselves only in form, order, and position. To provide for the motion that distributes them he conceived them as separated from one another by empty space. From this it follows that the void is as real as matter, or, as Democritus himself is reputed to have said, “thing is not more real than no-thing.”

But atomism has not been by any means universally regarded as the most satisfactory conception of the relation between space and matter. Not only does it require two kinds of being, with the different attributes of extension and hardness, respectively, but it would also seem to be experimentally inadequate in the case of the more subtle physical processes, such as light. The former of these is a speculative consideration, and as such had no little weight with the French philosopher Descartes, whose divisions and definitions so profoundly affected the course of thought in these matters after the sixteenth century. Holding also “that a vacuum or space in which there is absolutely no body is repugnant to reason,” and that an indivisible space-filling particle is self-contradictory, he was led to identify space and matter; that is, to make matter as indispensable to space as space to matter. There is, then, but one kind of corporeal being, whose attribute is extension, and whose modes are motion and rest. The most famous application of the mechanical conceptions which he bases upon this first principle, is his theory of the planets, which are conceived to be embedded in a transparent medium, and to move with it, vortex fashion, about the sun.

But the conception of the space-filling continuity of material substance owes its prominence at the present time to the experimental hypothesis of ether. This substance, originally conceived to occupy the intermolecular spaces and to serve as a medium for the propagation of undulations, is now regarded by many physicists as replacing matter. “It is the great hope of science at the present day,” says a contemporary exponent of naturalism, “that hard and heavy matter will be shown to be ether in motion." Such a theory would reduce bodies to the relative displacements of parts of a continuous substance, which would be first of all defined as spacial, and would possess such further properties as special scientific hypotheses might require.

Two broadly contrasting theories thus appear: that which defines matter as a continuous substance coextensive with space; and that which defines it as a discrete substance divided by empty space. But both theories are seriously affected by the peculiarly significant development of the conception of force.

Sec. In the Cartesian system the cause of motion was pressure within a plenum. But in the seventeenth century this notion encountered the system of Newton, a system which seemed to involve action at a distance. In the year 1728 Voltaire wrote from London:

“When a Frenchman arrives in London, he finds a very great change, in philosophy as well as in most other things. In Paris he left the world all full of matter; here he finds absolute vacua. At Paris the universe is seen filled up with ethereal vortices, while here the same space is occupied with the play of the invisible forces of gravitation. In Paris the earth is painted for us longish like an egg, and in London it is oblate like a melon. At Paris the pressure of the moon causes the ebb and flow of tides; in England, on the other hand, the sea gravitates toward the moon, so that at the same time when the Parisians demand high water of the moon, the gentlemen of London require an ebb."

But these differences are not matters of taste, nor even rival hypotheses upon an equal footing. The Newtonian system of mechanics, the consummation of a development initiated by Galileo, differed from the vortex theory of Descartes as exact science differs from speculation and unverified conjecture. And this difference of method carried with it eventually certain profound differences of content, distinguishing the Newtonian theory even from that of Democritus, with which it had so much in common. Although Democritus had sought to avoid the element of purposiveness in the older hylozoism by referring the motions of bodies as far as possible to the impact of other bodies, he nevertheless attributed these motions ultimately to weight, signifying thereby a certain downward disposition. Now it is true that in his general belief Newton himself is not free from hylozoism. He thought of the motions of the planets themselves as initiated and quickened by a power emanating ultimately from God. They are “impressed by an intelligent Agent,” and

“can be the effect of nothing else than the wisdom and skill of a powerful ever-living Agent who, being in all places, is more able by his will to move the bodies within his boundless uniform sensorium, and thereby to form and reform the parts of the universe, than we are by our will to move the parts of our own bodies."

But by the side of these statements must be set his famous disclaimer, “hypotheses non fingo.” In his capacity of natural philosopher he did not seek to explain motions, but only to describe them. Disbelieving as he did in action at a distance, he saw no possibility of explanation short of a reference of them to God; but such “hypotheses” he thought to be no proper concern of science. As a consequence, the mathematical formulation of motions came, through him, to be regarded as the entire content of mechanics. The notion of an efficient cause of motion is still suggested by the term force, but even this term within the system of mechanics refers always to a definite amount of motion, or measurement of relative motion. And the same is true of attraction, action, reaction, and the like. The further explanation of motion, the definition of a virtue or potency that produces it, first a neglected problem, then an irrelevant problem, is finally, for a naturalistic philosophy in which this progression is completed, an insoluble problem. For the sequel to this purely descriptive procedure on the part of science is the disavowal of “metaphysics” by those who will have no philosophy but science. Thus the scientific conservatism of Newton has led to the positivistic and agnostic phase of naturalism. But a further treatment of this development must be reserved until the issue of epistemology shall have been definitely raised.

A different emphasis within the general mechanical scheme, attaching especial importance to the conceptions of force and energy, has led to a rival tendency in science and a contrasting type of naturalism. The mechanical hypotheses hitherto described are all of a simple and readily depicted type. They suggest an imagery quite in accord with common-sense and with observation of the motions of great masses like the planets. Material particles are conceived to move within a containing space; the motions of corpuscles, atoms, or the minute parts of ether, differing only in degree from those of visible bodies. The whole physical universe may be represented in the imagination as an aggregate of bodies participating in motions of extraordinary complexity, but of one type. But now let the emphasis be placed upon the determining causes rather than upon the moving bodies themselves. In other words, let the bodies be regarded as attributive and the forces as substantive. The result is a radical alteration of the mechanical scheme and the transcendence of common-sense imagery. This was one direction of outgrowth from the work of Newton. His force of gravitation prevailed between bodies separated by spaces of great magnitude. Certain of the followers of Newton, notably Côtés, accepting the formulas of the master but neglecting his allusions to the agency of God, accepted the principle of action at a distance. Force, in short, was conceived to pervade space of itself. But if force be granted this substantial and self-dependent character, what further need is there of matter as a separate form of entity? For does not the presence of matter consist essentially in resistance, itself a case of force? Such reflections as these led Boscovich and others to the radical departure of defining material particles as centres of force.

Sec. But a more fruitful hypothesis of the same general order is due to the attention directed to the conception of energy, or capacity for work, by experimental discoveries of the possibility of reciprocal transformations without loss, of motion, heat, electricity, and other processes. The principle of the conservation of energy affirms the quantitative constancy of that which is so transformed, measured, for example, in terms of capacity to move units of mass against gravity. The exponents of what is called “energetics” have in many cases come to regard that the quantity of which is so conserved, as a substantial reality whose forms and distributions compose nature. A contemporary scientist, whose synthetic and dogmatic habit of mind has made him eminent in the ranks of popular philosophy, writes as follows:

“Mechanical and chemical energy, sound and heat, light and electricity, are mutually convertible; they seem to be but different modes of one and the same fundamental force or energy. Thence follows the important thesis of the unity of all natural forces, or, as it may also be expressed, the ‘monism of energy.’"

The conception of energy seems, indeed, to afford an exceptional opportunity to naturalism. We have seen that the matter-motion theory was satisfied to ignore, or regard as insoluble, problems concerning the ultimate causes of things. Furthermore, as we shall presently see to better advantage, the more strictly materialistic type of naturalism must regard thought as an anomaly, and has no little difficulty with life. But the conception of energy is more adaptable, and hence better qualified to serve as a common denominator for various aspects of experience. The very readiness with which we can picture the corpuscular scheme is a source of embarrassment to the seeker after unity. That which is so distinct is bristling with incompatibilities. The most aggressive materialist hesitates to describe thought as a motion of bodies in space. Energy, on the other hand, exacts little if anything beyond the character of measurable power. Thought is at any rate in some sense a power, and to some degree measurable. Recent discoveries of the dependence of capacity for mental exertion upon physical vitality and measurements of chemical energy received into the system as food, and somehow exhausted by the activities of thought, have lent plausibility to the hypothesis of a universal energy of which physical and “psychical” processes are alike manifestations. And the conception of energy seems capable not only of unifying nature, but also of satisfying the metaphysical demand for an efficient and moving cause. This term, like “force” and “power,” is endowed with such a significance by common sense. Indeed, naturalism would seem here to have swung round toward its hylozoistic starting-point. The exponent of energetics, like the naïve animistic thinker, attributes to nature a power like that which he feels welling up within himself. When he acts upon the environment, like meets like. Energetics, it is true, may obtain a definite meaning for its central conception from the measurable behavior of external bodies, and a meaning that may be quite free from vitalism or teleology. But in his extension of the conception the author of a philosophical energetics abandons this strict meaning, and blends his thought even with a phase of subjectivism, known as panpsychism. This theory regards the inward life of all nature as homogeneous with an immediately felt activity or appetency, as energetics finds the inner life to be homogeneous with the forces of nature. Both owe their philosophical appeal to their apparent success in unifying the world upon a direct empirical basis, and to their provision for the practical sense of reality.

Such, in brief, are the main alternatives available for a naturalistic theory of being, in consequence of the historical development of the fundamental conceptions of natural science.

Sec. We turn now to an examination of the manner in which naturalism, equipped with working principles, seeks to meet the special requirements of philosophy. The conception of the unity of nature is directly in the line of a purely scientific development, but naturalism takes the bold and radical step of regarding nature so unified as coextensive with the real, or at any rate knowable, universe. It will be remembered that among the early Greeks Anaxagoras had referred the creative and formative processes of nature to a non-natural or rational agency, which he called the Nous. The adventitious character of this principle, the external and almost purely nominal part which it played in the actual cosmology of Anaxagoras, betrayed it into the hands of the atomists, with their more consistently naturalistic creed. Better, these maintain, the somewhat dogmatic extension of conceptions proved to be successful in the description of nature, than a vague dualism which can serve only to distract the scientific attention and people the world with obscurities. There is a remarkable passage in Lucretius in which atomism is thus written large and inspired with cosmical eloquence:

“For verily not by design did the first-beginnings of things station themselves each in its right place guided by keen intelligence, nor did they bargain sooth to say what motions each should assume, but because many in number and shifting about in many ways throughout the universe, they are driven and tormented by blows during infinite time past, after trying motions and unions of every kind at length they fall into arrangements such as those out of which our sum of things has been formed, and by which too it is preserved through many great years, when once it has been thrown into the appropriate motions, and causes the streams to replenish the greedy sea with copious river waters, and the earth, fostered by the heat of the sun, to renew its produce, and the race of living things to come up and flourish, and the gliding fires of ether to live: all which these several things could in no wise bring to pass, unless a store of matter could rise up from infinite space, out of which store they are wont to make up in due season whatever has been lost."

The prophecy of La Place, the great French mathematician, voices the similar faith of the eighteenth century in a mechanical understanding of the universe:

“The human mind, in the perfection it has been able to give to astronomy, affords a feeble outline of such an intelligence. Its discoveries in mechanics and in geometry, joined to that of universal gravitation, have brought it within reach of comprehending in the same analytical expressions the past and future states of the system of the world."

As for God, the creative and presiding intelligence, La Place had “no need of any such hypothesis.”

Sec. But these are the boasts of Homeric heroes before going into battle. The moment such a general position is assumed there arise sundry difficulties in the application of naturalistic principles to special interests and groups of facts. It is one thing to project a mechanical scheme in the large, but quite another to make explicit provision within it for the origin of nature, for life, for the human self with its ideals, and for society with its institutions. The naturalistic method of meeting these problems involves a reduction all along the line in the direction of such categories as are derived from the infra-organic world. That which is not like the planetary system must be construed as mechanical by indirection and subtlety.

Sec. The origin of the present known natural world was the first philosophical question to be definitely met by science. The general form of solution which naturalism offers is anticipated in the most ancient theories of nature. These already suppose that the observed mechanical processes of the circular or periodic type, like the revolutions and rotations of the stars, are incidents in a historical mechanical process of a larger scale. Prior to the present fixed motions of the celestial bodies, the whole mass of cosmic matter participated in irregular motions analogous to present terrestrial redistributions. Such motions may be understood to have resulted in the integration of separate bodies, to which they at the same time imparted a rotary motion. It is such a hypothesis that Lucretius paints in his bold, impressionistic colors.

But the development of mechanics paved the way for a definite scientific theory, the so-called “nebular hypothesis,” announced by La Place in 1796, and by the philosopher Kant at a still earlier date. Largely through the Newtonian principle of the parallelogram of forces, the present masses, orbits, and velocities were analyzed into a more primitive process of concentration within a nebulous or highly diffused aggregate of matter. And with the aid of the principle of the conservation of energy this theory appears to make possible the derivation of heat, light, and other apparently non-mechanical processes from the same original energy of motion.

But a persistently philosophical mind at once raises the question of the origin of this primeval nebula itself, with a definite organization and a vast potential energy that must, after all, be regarded as a part of nature rather than its source. Several courses are here open to naturalism. It may maintain that the question of ultimate origin is unanswerable; it may regard such a process of concentration as extending back through an infinitely long past; or, and this is the favorite alternative for more constructive minds, the historical cosmical process may be included within a still higher type of periodic process, which is regarded as eternal. This last course has been followed in the well-known synthetic naturalism of Herbert Spencer. “Evolution,” he says, “is the progressive integration of matter and dissipation of motion.” But such a process eventually runs down, and may be conceived as giving place to a counter-process of devolution which scatters the parts of matter and gathers another store of potential motion. The two processes in alternation will then constitute a cosmical system without beginning or end.

In such wise a sweeping survey of the physical universe may be thought in the terms of natural science. The uniformitarian method in geology, resolving the history of the crust of the earth into known processes, such as erosion and igneous fusion; and spectral analysis, with its discoveries concerning the chemical constituents of distant bodies through the study of their light, have powerfully reenforced this effort of thought, and apparently completed an outline sketch of the universe in terms of infra-organic processes.

Sec. But the cosmos must be made internally homogeneous in these same terms. There awaits solution, in the first place, the serious problem of the genesis and maintenance of life within a nature that is originally and ultimately inorganic. The assimilation of the field of biology and physiology to the mechanical cosmos had made little real progress prior to the nineteenth century. Mechanical theories had, indeed, been projected in the earliest age of philosophy, and proposed anew in the seventeenth century. Nevertheless, the structural and functional teleology of the organism remained as apparently irrefutable testimony to the inworking of some principle other than that of mechanical necessity. Indeed, the only fruitful method applicable to organic phenomena was that which explained them in terms of purposive adaptation. And it was its provision for a mechanical interpretation of this very principle that gave to the Darwinian law of natural selection, promulgated in 1859 in the “Origin of Species,” so profound a significance for naturalism. It threatened to reduce the last stronghold of teleology, and completely to dispense with the intelligent Author of nature.

Darwin’s hypothesis sought to explain the origin of animal species by survival under competitive conditions of existence through the possession of a structure suited to the environment. Only the most elementary organism need be presupposed, together with slight variations in the course of subsequent generations, and both may be conceived to arise mechanically. There will then result in surviving organisms a gradual accumulation of such variations as promote survival under the special conditions of the environment. Such a principle had been suggested as early as the time of Empedocles, but it remained for Darwin to establish it with an unanswerable array of observation and experimentation. If any organism whatsoever endowed with the power of generation be allowed to have somehow come to be, naturalism now promises to account for the whole subsequent history of organic phenomena and the origin of any known species.

Sec. But what of life itself? The question of the derivation of organic from inorganic matter has proved insoluble by direct means, and the case of naturalism must here rest upon such facts as the chemical homogeneity of these two kinds of matter, and the conformity of physiological processes to more general physical laws. Organic matter differs from inorganic only through the presence of proteid, a peculiar product of known elements, which cannot be artificially produced, but which is by natural means perpetually dissolved into these elements without any discoverable residuum. Respiration may be studied as a case of aerodynamics, the circulation of the blood as a case of hydrodynamics, and the heat given off in the course of work done by the body as a case of thermodynamics. And although vitalistic theories still retain a place in physiology, as do teleological theories in biology, on the whole the naturalistic programme of a reduction of organic processes to the type of the inorganic tends to prevail.

Sec. The history of naturalism shows that, as in the case of life, so also in the case of mind, its hypotheses were projected by the Greeks, but precisely formulated and verified only in the modern period of science. In the philosophy of Democritus the soul was itself an atom, finer, rounder, and smoother than the ordinary, but thoroughly a part of the mechanism of nature. The processes of the soul are construed as interactions between the soul and surrounding objects. In sensation, the thing perceived produces images by means of effluxes which impinge upon the soul-atom. These images are not true reports of the outer world, but must be revised by thought before its real atomic structure emerges. For this higher critical exercise of thought Democritus devised no special atomic genesis. The result may be expressed either as the invalidity of such operations of mind as he could provide for in his universe, or the irreducibility to his chosen first principles of the very thought which defined them. Later naturalism has generally sacrificed epistemology to cosmology, and reduced thought to sensation. Similarly, will has been regarded as a highly developed case of instinct. Knowledge and will, construed as sensation and instinct, may thus be interpreted in the naturalistic manner within the field of biology.

Sec. But the actual content of sensation, and the actual feelings which attend upon the promptings of instinct, still stubbornly testify to the presence in the universe of something belonging to a wholly different category from matter and motion. The attitude of naturalism in this crucial issue has never been fixed and unwavering, but there has gradually come to predominate a method of denying to the inner life all efficacy and real significance in the cosmos, while admitting its presence on the scene. It is a strange fact of history that Descartes, the French philosopher who prided himself on having rid the soul of all dependence on nature, should have greatly contributed to this method. But it is perhaps not so strange when we consider that every dualism is, after all, symmetrical, and that consequently whatever rids the soul of nature at the same time rids nature of the soul. It was Descartes who first conceived the body and soul to be utterly distinct substances. The corollary to this doctrine was his automatism, applied in his own system to animals other than man, but which those less concerned with religious tradition and less firmly convinced of the soul’s originating activity were not slow to apply universally. This theory conceived the vital processes to take place quite regardless of any inner consciousness, or even without its attendance. To this radical theory the French materialists of the eighteenth century were especially attracted. With them the active soul of Descartes, the distinct spiritual entity, disappeared. This latter author had himself admitted a department of the self, which he called the “passions,” in which the course and content of mind is determined by bodily conditions. Extending this conception to the whole province of mind, they employed it to demonstrate the thorough-going subordination of mind to body. La Mettrie, a physician and the author of a book entitled “L’Homme Machine,” was first interested in this thesis by a fever delirium, and afterward adduced anatomical and pathological data in support of it. The angle from which he views human life is well illustrated in the following:

“What would have sufficed in the case of Julius Cæsar, of Seneca, of Petronius, to turn their fearlessness into timidity or braggartry? An obstruction in the spleen, the liver, or the vena portae. For the imagination is intimately connected with these viscera, and from them arise all the curious phenomena of hypochondria and hysteria. . . . ’A mere nothing, a little fibre, some trifling thing that the most subtle anatomy cannot discover, would have made two idiots out of Erasmus and Fontenelle.’"

Sec. The extreme claim that the soul is a physical organ of the body, identical with the brain, marked the culmination of this militant materialism, so good an instance of that over-simplification and whole-hearted conviction characteristic of the doctrinaire propagandism of France. Locke, the Englishman, had admitted that possibly the substance which thinks is corporeal. In the letters of Voltaire this thought has already found a more positive expression:

“I am body, and I think; more I do not know. Shall I then attribute to an unknown cause what I can so easily attribute to the only fruitful cause I am acquainted with? In fact, where is the man who, without an absurd godlessness, dare assert that it is impossible for the Creator to endow matter with thought and feeling?"

Finally, Holbach, the great systematizer of this movement, takes the affair out of the hands of the Creator and definitively announces that “a sensitive soul is nothing but a human brain so constituted that it easily receives the motions communicated to it."

This theory has been considerably tempered since the age of Holbach. Naturalism has latterly been less interested in identifying the soul with the body, and more interested in demonstrating its dependence upon specific bodily conditions, after the manner of La Mettrie. The so-called higher faculties, such as thought and will, have been related to central or cortical processes of the nervous system, processes of connection and complication which within the brain itself supplement the impulses and sensations congenitally and externally stimulated. The term “epiphenomenon” has been adopted to express the distinctness but entire dependence of the mind. Man is “a conscious automaton.” The real course of nature passes through his nervous system, while consciousness attends upon its functions like a shadow, present but not efficient.

Sec. Holbach’s “Système de la Nature,” published in 1770, marks the culmination of the unequivocally materialistic form of naturalism. Its epistemological difficulties, always more or less in evidence, have since that day sufficed to discredit materialism, and to foster the growth of a critical and apologetic form of naturalism known as positivism or agnosticism. The modesty of this doctrine does not, it is true, strike very deep. For, although it disclaims knowledge of ultimate reality, it also forbids anyone else to have any. Knowledge, it affirms, can be of but one type, that which comprises the verifiable laws governing nature. All questions concerning first causes are futile, a stimulus only to excursions of fancy popularly mistaken for knowledge. The superior certainty and stability which attaches to natural science is to be permanently secured by the savant’s steadfast refusal to be led away after the false gods of metaphysics.

But though this is sufficient ground for an agnostic policy, it does prove an agnostic theory. The latter has sprung from a closer analysis of knowledge, though it fails to make a very brave showing for thoroughness and consistency. The crucial point has already been brought within our view. The general principles of naturalism require that knowledge shall be reduced to sensations, or impressions of the environment upon the organism. But the environment and the sensations do not correspond. The environment is matter and motion, force and energy; the sensations are of motions, to be sure, but much more conspicuously of colors, sounds, odors, pleasures, and pains. Critically, this may be expressed by saying that since the larger part of sense-perception is so unmistakably subjective, and since all knowledge alike must be derived from this source, knowledge as a whole must be regarded as dealing only with appearances. There are at least three agnostic methods progressing from this point. All agree that the inner or essential reality is unfathomable. But, in the first place, those most close to the tradition of materialism maintain that the most significant appearances, the primary qualities, are those which compose a purely quantitative and corporeal world. The inner essence of things may at any rate be approached by a monism of matter or of energy. This theory is epistemological only to the extent of moderating its claims in the hope of lessening its responsibility. Another agnosticism places all sense qualities on a par, but would regard physics and psychology as complementary reports upon the two distinct series of phenomena in which the underlying reality expresses itself. This theory is epistemological to the extent of granting knowledge, viewed as perception, as good a standing in the universe as that which is accorded to its object. But such a dualism tends almost irresistibly to relapse into materialistic monism, because of the fundamental place of physical conceptions in the system of the sciences. Finally, in another and a more radical phase of agnosticism, we find an attempt to make full provision for the legitimate problems of epistemology. The only datum, the only existent accessible to knowledge, is said to be the sensation, or state of consciousness. In the words of Huxley:

“What, after all, do we know of this terrible ‘matter’ except as a name for the unknown and hypothetical cause of states of our own consciousness? And what do we know of that ‘spirit’ over whose threatened extinction by matter a great lamentation is arising, . . . except that it is also a name for an unknown and hypothetical cause, or condition, of states of consciousness?"

The physical world is now to be regarded as a construction which does not assimilate to itself the content of sensations, but enables one to anticipate them. The sensation signifies a contact to which science can provide a key for practical guidance.

Sec. This last phase of naturalism is an attempt to state a pure and consistent experimentalism, a workable theory of the routine of sensations. But it commonly falls into the error of the vicious circle. The hypothetical cause of sensations is said to be matter. From this point of view the sensation is a complex, comprising elaborate physical and physiological processes. But these processes themselves, on the other hand, are said to be analyzable into sensations. Now two such methods of analysis cannot be equally ultimate. If all of reality is finally reducible to sensations, then the term sensation must be used in a new sense to connote a self-subsistent being, and can no longer refer merely to a function of certain physiological processes. The issue of this would be some form of idealism or of the experience-philosophy that is now coming so rapidly to the front. But while it is true that idealism has sometimes been intended, and that a radically new philosophy of experience has sometimes been closely approached, those, nevertheless, who have developed experimentalism from the naturalistic stand-point have in reality achieved only a thinly disguised materialism. For the very ground of their agnosticism is materialistic. Knowledge of reality itself is said to be unattainable, because knowledge, in order to come within the order of nature, must be regarded as reducible to sensation; and because sensation itself, when regarded as a part of nature, is only a physiological process, a special phenomenon, in no way qualified to be knowledge that is true of reality.

Sec. Perhaps, after all, it would be as fair to the spirit of naturalism to relieve it of responsibility for an epistemology. It has never thoroughly reckoned with this problem. It has deliberately selected from among the elements of experience, and been so highly constructive in its method as to forfeit its claim to pure empiricism; and, on the other hand, has, in this same selection of categories and in its insistence upon the test of experiment, fallen short of a thorough-going rationalism. While, on the one hand, it defines and constructs, it does so, on the other hand, within the field of perception and with constant reference to the test of perception. The explanation and justification of this procedure is to be found in the aim of natural science rather than in that of philosophy. It is this special interest, rather than the general problem of being, that determines the order of its categories. Naturalism as an account of reality is acceptable only so far as its success in satisfying specific demands obtains for it a certain logical immunity. These demands are unquestionably valid and fundamental, but they are not coextensive with the demand for truth. They coincide rather with the immediate practical need of a formulation of the spacial and temporal changes that confront the will. Hence naturalism is acceptable to common-sense as an account of what the every-day attitude to the environment treats as its object. Naturalism is common-sense about the “outer world,” revised and brought up to date with the aid of the results of science. Its deepest spring is the organic instinct for the reality of the tangible, the vital recognition of the significance of that which is on the plane of interaction with the body.

Sec. Oddly enough, although common-sense is ready to intrust to naturalism the description of the situation of life, it prefers to deal otherwise with its ideals. Indeed, common-sense is not without a certain suspicion that naturalism is the advocate of moral reversion. It is recognized as the prophecy of the brute majority of life, of those considerations of expediency and pleasure that are the warrant for its secular moods rather than for its sustaining ideals. And that strand of life is indeed its special province. For the naturalistic method of reduction must find the key to human action among those practical conditions that are common to man and his inferiors in the scale of being. In short, human life, like all life, must be construed as the adjustment of the organism to its natural environment for the sake of preservation and economic advancement.

Sec. Early in Greek philosophy this general idea of life was picturesquely interpreted in two contrasting ways, those of the Cynic and the Cyrenaic. Both of these wise men postulated the spiritual indifference of the universe at large, and looked only to the contact of life with its immediate environment. But while the one hoped only to hedge himself about, the other sought confidently the gratification of his sensibilities. The figure of the Cynic is the more familiar. Diogenes of the tub practised self-mortification until his dermal and spiritual callousness were alike impervious. From behind his protective sheath he could without affectation despise both nature and society. He could reckon himself more blessed than Alexander, because, with demand reduced to the minimum, he could be sure of a surplus of supply. Having renounced all goods save the bare necessities of life, he could neglect both promises and threats and be played upon by no one. He was securely intrenched within himself, an unfurnished habitation, but the citadel of a king. The Cyrenaic, on the other hand, did not seek to make impervious the surface of contact with nature and society, but sought to heighten its sensibility, that it might become a medium of pleasurable feeling. For the inspiration with which it may be pursued this ideal has nowhere been more eloquently set forth than in the pages of Walter Pater, who styles himself “the new Cyrenaic.”

“Not the fruit of experience, but experience itself, is the end. A counted number of pulses only is given to us of a variegated, dramatic life. How may we see in them all that is to be seen in them by the finest senses? How shall we pass most swiftly from point to point, and be present always at the focus where the greatest number of vital forces unite in their purest energy?

To burn always with this hard, gemlike flame, to maintain this ecstacy, is success in life. . . . While all melts under our feet, we may well catch at any exquisite passion, or any contribution to knowledge that seems by a lifted horizon to set the spirit free for a moment, or any stirring of the senses, strange dyes, strange colors, and curious odors, or work of the artist’s hands, or the face of one’s friend. Not to discriminate every moment some passionate attitude in those about us, and in the brilliancy of their gifts some tragic dividing of forces on their ways, is, on this short day of frost and sun, to sleep before evening."

Sec. In the course of modern philosophy the ethics of naturalism has undergone a transformation and development that equip it much more formidably for its competition with rival theories. If the Cynic and Cyrenaic philosophies of life seem too egoistic and narrow in outlook, this inadequacy has been largely overcome through the modern conception of the relation of the individual to society. Man is regarded as so dependent upon social relations that it is both natural and rational for him to govern his actions with a concern for the community. There was a time when this relation of dependence was viewed as external, a barter of goods between the individual and society, sanctioned by an implied contract. Thomas Hobbes, whose unblushing materialism and egoism stimulated by opposition the whole development of English ethics, conceived morality to consist in rules of action which condition the stability of the state, and so secure for the individual that “peace” which self-interest teaches him is essential to his welfare.

“And therefore so long a man is in the condition of mere nature, which is a condition of war, as private appetite is the measure of good and evil: and consequently all men agree on this, that peace is good, and therefore also the ways or means of peace, which, as I have showed before, are ‘justice,’ ‘gratitude,’ ‘modesty,’ ‘equity,’ ‘mercy,’ and the rest of the laws of Nature, are good; that is to say, ‘moral virtues’; and their contrary ‘vices,’ evil."

Jeremy Bentham, the apostle of utilitarianism in the eighteenth century, defined political and social sanctions through which the individual could purchase security and good repute with action conducive to the common welfare. But the nineteenth century has understood the matter better and the idea of an evolution under conditions that select and reject, is here again the illuminating thought. No individual, evolutionary naturalism maintains, has survived the perils of life without possessing as an inalienable part of his nature, congenital like his egoism, certain impulses and instinctive desires in the interest of the community as a whole. The latest generation of a race whose perpetuation has been conditioned by a capacity to sustain social relations and make common cause against a more external environment, is moral, and does not adopt morality in the course of a calculating egoism. Conscience is the racial instinct of self-preservation uttering itself in the individual member, who draws his very life-blood from the greater organism.

Sec. This latest word of naturalistic ethics has not won acceptance as the last word in ethics, and this in spite of its indubitable truth within its scope. For the deeper ethical interest seeks not so much to account for the moral nature as to construe and justify its promptings. The evolutionary theory reveals the genesis of conscience, and demonstrates its continuity with nature, but this falls as far short of realizing the purpose of ethical study as a history of the natural genesis of thought would fall short of logic. Indeed, naturalism shows here, as in the realm of epistemology, a persistent failure to appreciate the central problem. Its acceptance as a philosophy, we are again reminded, can be accounted for only on the score of its genuinely rudimentary character. As a rudimentary phase of thought it is both indispensable and inadequate. It is the philosophy of instinct, which should in normal development precede a philosophy of reason, in which it is eventually assimilated and supplemented.

Sec. There is, finally, an inspiration for life which this philosophy of naturalism may convey atheism, its detractors would call it, but none the less a faith and a spiritual exaltation that spring from its summing up of truth. It is well first to realize that which is dispiriting in it, its failure to provide for the freedom, immortality, and moral providence of the more sanguine faith.

“For what is man looked at from this point of view? . . . Man, so far as natural science by itself is able to teach us, is no longer the final cause of the universe, the Heaven-descended heir of all the ages. His very existence is an accident, his story a brief and transitory episode in the life of one of the meanest of the planets. Of the combination of causes which first converted a dead organic compound into the living progenitors of humanity, science, indeed, as yet knows nothing. It is enough that from such beginnings famine, disease, and mutual slaughter, fit nurses of the future lords of creation, have gradually evolved, after infinite travail, a race with conscience enough to feel that it is vile, and intelligence enough to know that it is insignificant. . . . We sound the future, and learn that after a period, long compared with the individual life, but short indeed compared with the divisions of time open to our investigation, the energies of our system will decay, the glory of the sun will be dimmed, and the earth, tideless and inert, will no longer tolerate the race which has for a moment disturbed its solitude. Man will go down into the pit, and all his thoughts will perish. The uneasy consciousness, which in this obscure corner has for a brief space broken the contented silence of the universe, will be at rest. Matter will know itself no longer. ’Imperishable monuments’ and ‘immortal deeds,’ death itself, and love stronger than death, will be as though they had never been. Nor will anything that is be better or be worse for all that the labor, genius, devotion, and suffering of man have striven through countless generations to effect."

Sec. But though our philosopher must accept the truth of this terrible picture, he is not left without spiritual resources. The abstract religion provided for the agnostic faithful by Herbert Spencer does not, it is true, afford any nourishment to the religious nature. He would have men look for a deep spring of life in the negative idea of mystery, the apotheosis of ignorance, while religious faith to live at all must lay hold upon reality. But there does spring from naturalism a positive religion, whose fundamental motives are those of service, wonder, and renunciation: service of humanity in the present, wonder at the natural truth, and renunciation of a universe keyed to vibrate with human ideals.

“Have you,” writes Charles Ferguson, “had dreams of Nirvana and sickly visions and raptures? Have you imagined that the end of your life is to be absorbed back into the life of God, and to flee the earth and forget all? Or do you want to walk on air, or fly on wings, or build a heavenly city in the clouds? Come, let us take our kit on our shoulders, and go out and build the city here."

For Haeckel “natural religion” is such as

“the astonishment with which we gaze upon the starry heavens and the microscopic life in a drop of water, the awe with which we trace the marvellous working of energy in the motion of matter, the reverence with which we grasp the universal dominance of the law of substance throughout the universe."

There is a deeper and a sincerer note in the stout, forlorn humanism of Huxley:

“That which lies before the human race is a constant struggle to maintain and improve, in opposition to the State of Nature, the State of Art of an organized polity; in which, and by which, man may develop a worthy civilization, capable of maintaining and constantly improving itself, until the evolution of our globe shall have entered so far upon its downward course that the cosmic process resumes its sway; and, once more, the State of Nature prevails over the surface of our planet."

The best systematic presentation of “energetics” is to be found in Ostwald’s Vorlesungen ueber Natur-Philosophie. Herbert Spencer, in his well-known First Principles, makes philosophical use of both “force” and “energy.”