This new conception of nature, the evolutionary conception based on the analogy of history, has certain characteristics which follow necessarily from the central idea on which it is based. It may be useful to mention a few of them.
i. Change no longer cyclical, but progressive. The first to which I will refer is that change takes on, in the mind of the natural scientist, a new character. Greek, Renaissance, and modern thinkers have all agreed that everything in the world of nature, as we perceive it, is in a state of continuous change. But Greek thinkers regarded these natural changes as a bottom always cyclical. A change from a state A to a state B, they thought, is always one part of a process which completes itself by a return from state B to state A. When they found themselves forced to recognize the existence of a change that was not cyclical because it admitted of no such return, e.g. in the change from youth to age in an animal or vegetable organism, they regarded it as a mutilated fragment of a change which, had it been complete, would have been cyclical; and the thing which exhibited it, whether animal or vegetable or anything else, they regarded as defective for that the very reason, as not exhibiting in its changes that cyclic pattern which ideally all change ought to show. Alternatively, it was often possible to regard a non-cyclical change not as incomplete in itself but as incompletely known; as a case of cyclical change where for some reason we could perceive only one part of the revolution. This tendency to conceive change as at bottom, or when it is able to realize and exhibits its proper nature qua change, not progressive (where by progress I mean a change always leading to something new, with no necessary implication of betterment) but cyclical, was characteristic of the Greek mind throughout its history. I will quote only one striking example of it: the doctrine which haunts Greek cosmology from the Ionians to Aristotle, that the total movement of the world-organism, the movement from which all other movements in the natural world are derived, is a uniform rotation.
Modern thought reverses this state of things. Dominated by the idea of progress or development, which is derived from the principle that history never repeats itself, it regards the world of nature as a second world in which nothing is repeated, a second world of progress characterized, no less than that of history, by the constant emergence of new things. Change is at bottom progressive. Changes that appear to be cyclical are not really cyclical. It is always possible to explain them as cyclical in appearance only, and in reality progressive, in either of two ways: subjectively, by saying that what have been taken for identicals are only similars, or objectively, by saying (to speak metaphorically) that what ahs been taken for a rotary or circular movement is in fact a spiral movement, one in which the radius is constantly changing or the centre constantly displaced, or both.
ii. Nature no longer mechanical. A negative result of introducing the idea or evolution into natural science was the abandonment of the mechanical conception of nature.
It is impossible to describe one and the same thing in the same breath as a machine and as developing or evolving. Something which is developing may build itself machines, but it cannot be a machine. On the evolutionary theory, therefore, there may be machines in nature, but nature cannot itself be a machine, and cannot be either described as a whole or completely described as to any of its parts in mechanical terms.
A machine is essentially a finished product or closed system. Until it is finished it is not a machine. While it is being built it is not functioning as a machine; it cannot do that until it is complete; therefore it can never develop, for developing means working at becoming what as yet one is not (as, for example, a kitten works at growing into a cat), and a machine in an unfinished state cannot work at anything. The only kind of change which a machine can produce in itself by its functioning is breaking down or wearing out. This is not a case of development, because it is not an acquisition of any new functions, it is only a loss of old ones. Thus a steamship in working order can do all the things a broken-down one can do and others besides. A machine may bring about a kind of development in that on which it works, as a grain elevator may build a heap of grain; but if the machine is to go on working this development must be cancelled in the next phase (e.g. the heap must be cleared away), and a cycle of phases substituted for the development.
iii. Teleology reintroduced. A positive corollary of this negative result is the reintroduction into natural science of an idea which the mechanical view of nature had banished: the idea of teleology. If the world of nature is a machine or a collection of machines, everything that happens in it is due to ‘efficient causes’, not in the Aristotelian sense of that Aristotelian phrase but in the mechanistic sense, as denoting impact, attraction, repulsion, and so on. It is only when we discuss the relation of the machine to its makers that ‘final causes’ begin to appear. If nature is regarded as a machine, then teleology or final causation, with the attendant idea of ‘nisus’ or effort on the part of nature or something in nature towards the realization of something not yet existing, must be ruled out of natural science altogether; its proper application is to the sphere of mind; to apply it to nature is to confuse the characteristics of these two radically different things.
This negation of teleology in mechanistic natural science may undergo a qualification more apparent than real by contending, as Spinoza did in fact contend, that everything in nature makes an effort to maintain itself in its own being (‘in suo esse perseverare conatur’, Ethics, iii, prop. 6). This is only a quasi-teleology, because the conatus of which Spinoza writes is not directed towards the realization of anything not yet existing. Under a form of words which seems to assert the reality and university of effort, the very essence of effort is in fact denied.
For an evolutionary science of nature, the esse of anything in nature is its fieri; and a science of that kind must therefore replace Spinoza’s proposition by the proposition that a everything in nature tries to persevere in its own becoming: to continue the process of development in which, so far as it exists at all, it is already engaged. And this contradicts what Spinoza meant to say; for the ‘being’ of a thing, in Spinoza, means what it now is; and a thing engaged in a process of development is engaged in ceasing to be what is not is, e.g. a kitten, to become what it now is not, e.g. a cat.
iv. Substance resolved into function. The principle that the esse of a thing is its fieri requires a somewhat extensive reform in the vocabulary of natural science, such that all words and phrases descriptive of substance or structure shall be replaced by words and phrases descriptive of function. A mechanistic science of nature will already possess a considerable vocabulary of functional terms, but these will always be accompanied by another vocabulary of structural terms. In any machine structure is one thing, function another; for a machine has to be constructed before it can be set in motion.
In order to make a bearing you choose a piece of steel having a certain degree of hardness, and before it can function as a bearing you work it to a certain shape. Its size, shape, weight, hardness, and so forth are structural properties independent of its acting in this particular machine, or in any other machine, as a bearing or indeed as anything else. They remain the same whether or not the machine to which it belongs is in motion or at rest. Further, these structural properties belonging to a given part of a given machine, are the foundation and pre-requisite of its functional properties. Unless the piece of steel has the right shape, hardness, &c., it will not serve as a bearing.
If nature is a machine, therefore, the various motions of its parts will be motions of things which have structural properties of their own independent of these motions and serving as their indispensable prerequisites. To sum this up: in a machine, and therefore in nature if nature is mechanical, structure and function are distinct, and function presupposes structure.
In the world of human affairs as known to the historians there is no such distinction and a fortiori no such priority. Structure is resolvable into function. There is no harm in historians talking about the structure of feudal society or of capitalist industry or of the Greek city state, but the reason why there is no harm in it is because they know that these so-called structures are really complexes of function, kinds of ways in which human beings behave; and that when we say that, for example, the British constitution exists, what we mean is that certain people are behaving in a certain kind of way.
On an evolutionary view of nature a logically constructed natural science will follow the example of history and resolve the structures with which it is concerned into function. Nature will be understood as consisting of processes, and the existence of any special kind of thing in nature will be understood as meaning that processes of a special kind are going on there. Thus ‘hardness’ in steel will be understood, as in fact it is by modern physicists, not as the name for a structural property of the steel independent of, and presupposed by, any special way in which the steel may behave, but as the name for a way in which it behaves: for example, the name for a rapid movement of the particles composing it, whereby these violently bombard anything that is brought into what is called ‘contact’ with the steel, that is, within range of the bombardment.
v. Minimum space and minimum time. This resolution of structure into function has important consequences for the detail of natural science. Since the conception of any kind of natural substance is resolved into the conception of some kind of natural function; and since these functions are still conceived by natural scientists in the way in which they have been conceived ever since the dawn of Greek thought, namely, as movements; and since any movement occupies space and takes time; it follows that a given kind of natural substance can exist, according to the doctrines of an evolutionary natural science, only in an appropriate amount of space and during an appropriate amount of time. Let us take these two qualifications separately.
(a) The principle of minimum space. An evolutionary natural science will maintain that a given kind of natural substance can exist only in an appropriate amount of space. It is not infinitely divisible. There is a smallest possible quantity of it; and if that quantity is divided the parts are not specimens of that kind of substance.
This is the doctrine propounded by John Dalton early in the nineteenth century, and now universally accepted. It is called atomism, but it differs no less from the doctrine of the Greek atomists than it does from the homoeomerism of Anaxagoras. Anaxagoras held that specific natural substances were made up of particles homogeneous with themselves, and any such idea as this is in obvious conflict with Daltonian chemistry, according to which water, for example, is made up not of water but of oxygen and hydrogen, two gases. The Democritean atomism which we know from Epicurus and Lucretius, however, differs from Daltonian atomism quite as profoundly; for the Greek atoms were indivisible particles of undifferentiated matter, whereas Dalton’s atoms (until Rutherford began to split them) were indivisible particles of this or that kind of matter, hydrogen or carbon or lead.
Dalton divided natural substances into two classes: those made up of ‘molecules’ like water, and those made up of ‘atoms’, like hydrogen. In each case the particle, molecule or atom, was the smallest quantity of that substance which could exist: but not for the same reason. The molecule of water was the smallest possible amount of water because the only parts into which it could be divided were particles not of water but of oxygen and hydrogen. The atom of oxygen was the smallest possible amount of oxygen not because it was divisible into parts which were not oxygen but because it was not divisible at all.
This conception of a physically indivisible ‘atom’ was not new. It was a fossilized relic of ancient Greek physics, anachronistically surviving in an alien environment, the evolutionary science of the nineteenth century. The fertile part of the Daltonism was not the idea of the ‘atom’ but the idea of the ‘molecule’: not the Anaxagorean idea of particles homogenous with that which they go to make up, but the thoroughly modern idea that particles having determinate special qualities of their own could make up bodies having quite different special qualities. This idea is nowhere to be found in the Greeks. The theory of the ‘four elements’ in Empedocles is no anticipation of it; for according to that theory the elements earth, air, fire, and water preserve their special qualities in the compounds formed of them, so that these compound are, as to their own special qualities, in part earthy, in part airy, and so forth.
Indeed, the Daltonian ‘atom’ did not survive the nineteenth century. Before the century was over J. J. Thomson and others resolved the Daltonian dualism between the ‘atom’ and the ‘molecule’ and brought the theory of the atom into line with the theory of the molecule. This was done by maintaining that, just as the ‘molecule’ of water was made up of parts which taken separately were not water but something else, namely oxygen and hydrogen, so the ‘atom’ of oxygen was made up of parts which taken separately were not oxygen but something else, namely, electricity.
(b) The principle of minimum time. An evolutionary science of nature will maintain that a natural substance takes time to exist; an appropriate amount of time, different kinds of substance taking each its own specific amount. For each specific substance there is a specific time-lapse during which it can exist; in a shorter time-lapse it cannot exist, because the specific function or process whose occurrence is what we mean when we speak of the specific substance as existing cannot occur in so short a time.
If the suggestion made above was correct, that evolutionary natural science is based on analogy with historical science, and if history is the study of human affairs, human affairs should present us with analogies for this principle, just as they present us with analogies for the principle of minimum space in, for example, the fact that a given type of human activity involves as a minimum a certain number of human beings: that it takes two to make a quarrel, three to make a case of jealousy, four or five (if Plato is right, Republic, 369 D) to make a civil society, and so on. And these analogies in human affairs for the principle of minimum time should have been commonplace long before that principle began to affect the work of natural scientists.
This is in fact the case. A typical and famous example is Aristotle’s remark (Eth. Nic. 1098/18) that being happy is an activity which requires a whole lifetime, and cannot exist in less. So, notoriously, with activities like being a strategist or a statesman or a musical composer. Perhaps no one can say exactly how long these take to exist; but one might suggest that to be a strategist requires at least the time of one campaign; to be a statesman, the time of framing and enacting one piece of legislation; to be a composer, the time of composing one musical work. Let t be the time taken by any one of these activities. Then the occurrence of that activity is possible only granted the occurrence of other activities, occupying a time less than t, which in a loose sense of the phrase may be called the ‘parts’ of which it is composed. Say a man takes a year to write a book, during a certain minute of that year he writes one sentence and in that sense the writing of the book is a whole of which writing each sentence of it is one part. These ‘parts’ are not homogeneous with each other or with the ‘whole’. Each sentence is the solution of a special problem with its own peculiar characteristics; and the book as a whole is the solution of a problem not like any of these.
Elsewhere Aristotle comes near to applying this notion to things in nature. He points out that ‘movements’ are made up of parts not homogenous with each other or with the wholes they make up. He gives as examples the building of a temple and walking. He analyses the former example; I will offer analysis of the latter. When a man walks at three miles an hour, making three steps in every two seconds, during any given hundredth of a second he cannot properly be said to be walking, for walking is a kind of locomotion effected by standing on each foot alternately while swinging the other forward; he is standing on one foot and raising the other from the ground, or moving it forward, or putting it down with his weight behind it, or standing on the toe of one foot and the heel of the other, or the like. How long exactly it takes for the rhythmical action which is called walking to establish itself may be a question difficult or even impossible to answer with certainty; but clearly a hundredth of a second is not enough.
Aristotle’s use here of the word ‘movement’ suggests the famous argument of Zeno the Eleatic. At any given instant, said Zeno, a flying arrow is not in motion; it is at rest, occupying the space equal to itself in which it is situated; so that if time is nothing but a sum of instants the arrow is never in motion at all. Aristotle, in the passage referred to, points out that a determinate kind of motion requires for its occurrence a determinate lapse of time; which leaves the reader free to answer Zeno, if he will, by saying ‘How long exactly it takes for an arrow to be in motion I do not know; but some lapse of time is required. Let an instant be defined as any lapse of time shorter than that; then no contradiction is involved between saying that in a given instant the arrow is at rest and that time is made up of instants, and saying that during a longer period of time the arrow moves.’
Aristotle does not say this; nor is there any evidence that he mean to suggest it. All he says is that a movement of a certain determinate kind is made up of movements not of that kind. That movement as such is made up of parts which are not movement at all he would no doubt have denied. The answer to Zeno which, I have said, he leaves his reader free to make would be a good answer only if it were implemented by a physical theory according to which the arrow, even when ‘at rest’, were conceived as a microcosm of particles all moving so rapidly that the rhythms of their movement could establish themselves in a lapse of time shorter than that which ex hypothesi it takes for the arrow to ‘be in motion’.
This is in fact how the arrow is conceived in modern physics. Zeno is answered by negating the hypothesis underlying his argument. We must not say that Zeno is ‘refuted’, because although his argument is easy to understand in itself, there is much doubt among scholars as to what he meant it to prove: what exactly the problem was upon which he was trying to throw light. It is clear, however, that among the terms of the problem was the distinction between an arrow’s being ‘in motion’ when it is shot through the air and its being ‘at rest’ when it stands in the quiver or lies on the ground. Evolutionary physics denies this distinction. The arrow is made, say, partly of wood and partly of iron. Each of these is composed of minute particles which move incessantly; those of the wood move in one way, those of the iron in anther. These particles are themselves composed of particles still more minute, moving again in ways of their own. However far the physicist can push his analysis, he never arrives at particles which are at rest, and never at particles which behave in exactly the same way as that which they compose. Nor does he think of any one of them, at any stage, as behaving in exactly the same way as any other: on the contrary, the ‘laws’ according to which he thinks of them as moving are, in his own phrase, ‘statistical laws’, descriptive of their average behavior in the mass, not of their individual behavior when taken separately.
According to the principle of minimum space, wherever there is a natural substance s¹ (such as water), there is a smallest possible quantity of it (the molecule of water), anything less than which will be not a piece of that substance but a piece of a different substance (oxygen or hydrogen). According to the principle of minimum time, there is a minimum t, during which the movements of the (oxygen and hydrogen) atoms within a single molecule (of water) can establish their rhythm and thus constitute that single molecule. In a lapse of time smaller than t, the (oxygen and hydrogen) atoms exist, but the molecule does not exist. There is no s¹; there is only s², the class of substance to which oxygen and hydrogen belong.
But the particles of s² are themselves made up of smaller moving particles (electrons, nuclei; up to now the complete analysis has not been finally arrived at); and these will be particles not of s², but of s³ (electricity, negative and positive).
The principles of minimum space and minimum time apply once more. There will be a smallest possible quantity of s² (the atom of oxygen and hydrogen), not necessarily the same for all the different kinds of substance included in that class; the smallest possible quantity of s³ will be very much smaller. There will also be a smallest possible lapse of time t² during which the movements of the s³ particles within a single s² particle can establish their rhythm and thus constitute that s² particle; a lapse of time not necessarily the same in length for the various kinds of substance included in the s² class, but in every case falling within the limits implied by calling it t². In a lapse of time smaller than t² there are, therefore, no substances belonging to the class s²; there is only s³.
If the question is raised, therefore, whether a given thing is an example of s¹, of s², or of s³, the answer depends on the question: In how long a time? If in a time of the order of t, it is an example of s¹; if in a time of the order of t², it is an example of s²; if in a time of the order of t³, it is an example of s³. Different orders of substance take different orders of time-lapse to exist.
The implications of this principle have been worked out by Professor A. N. Whitehead and summarized in his dictum that ‘there is no matter at an instant’. (Nature and Life, 1934, p. 48.). The tendency of all modern science of nature is to resolve substance into function. All natural functions are forms of motion, and all motion takes time. At an instant, not the ‘instant’ of ‘instantaneous’ photography, which contains a measurable time-lapse, but a mathematical instant containing no time-lapse at all, there can be no motion, and therefore no natural function, and therefore no natural substance.
The principle, it may be observed in passing, opens no door to subjective idealism. One might express it by saying that how the world of nature appears to us depends on how long we take to observe it: that to a person who took a view of it extending over a thousand years it would appear in one way, to a person who took a view of it extending over a thousandth of a second it would appear in a different way, but that each of these is mere appearance, due to the fact that we take exactly so much time to make our observation.
This, though true, would be misleading. The water which in order to exist requires a time of the order of t¹ is just as real as the oxygen and hydrogen atoms composing it, which require a time of the order of t²; and these are just as real as the electrons and nuclei composing them, which require a still less time. How the natural world appears to us does certainly depend on how long we take to observe it; but that is because when we observe it for a certain length of time we observe the processes which require that length of time in order to occur.
Another dangerous way of stating the principle is by propounding the hypothesis: Suppose all movement in nature were to stop; and asking, What would be left? According to Greek physics, and equally according to Renaissance ideas which, with special reference to their formulation by Newton, are nowadays known as ‘classical physics’, what would be left is the corpse of nature, a cold dead world, like a derelict steam-engine. According to modern physics nothing whatever would be left. This is dangerous because the hypothesis according to which nothing would be left is, for modern physics, a nonsense hypothesis: it implies a distinction between substance and function, and their distinction is exactly what modern physics denies.
The principle may, however, be illustrated by means of other hypotheses incapable of practical realization but not in themselves nonsensical. Our experimental knowledge of the natural world is based on our acquaintance with those natural processes which we can observe experimentally. This acquaintance is limited downwards in space and time by our inability to observe any process that occupies less than a certain amount of space or a certain lapse of time, and upwards by the impossibility of observing any process that occupies more space or more time than the range of human vision or the time covered by human records, or even by the mere inconvenience of observing processes that take longer than the time during which it is easy for us to devote our time to watching them. These limits, upper and lower, of our observations in space and time have been greatly enlarged by the apparatus of the modern scientist, but they still exist, and are ultimately imposed on us by our constitution as animals of a definite size and living at a definite rate. Animals much larger or much smaller than ourselves, whose lives ran in a much slower or a much faster rhythm, would observe processes of a very different kind, and would reach by these observations a very different idea from our own as to what the natural world is like.
Thus the new cosmology entails a certain skepticism as to the validity of any argument which, starting from our own observations, inductively reasons that what we have observed is a fair sample of nature in its entirety. Such arguments are doubtless valid in a sense that the processes we observe may be a fair sample of processes, whether observable or unobservable to ourselves, having the same order or extension in space or time; but they cannot tell us anything about processes very much larger or smaller in space or very much longer or shorter in time. The natural world which human scientists can study by observation and experiment is an anthropocentric world; it consists only of those natural processes whose time-phase and space-range are within the limits of our observation.
This skepticism involves no doubt as to the validity of our observational methods within their own proper field. We still inherit the methods of Renaissance science in this point at least: that we hold no theory to be acceptable until it has been confirmed by observation and experiment; and the ‘theory’ that natural processes have one type of character within one range of magnitude in space and time, and another when their space-range or time-lapse is different, has been amply confirmed in this way. It is one result, and not the least important, of that enlargement of the limits of our observation by means of modern scientific apparatus, that we are able within our limits as thus enlarged to compare the largest-scale with the smallest-scale processes thus revealed to us, and to note their differences from each other and from those with which observation not so aided acquaints us.
In this way it has been discovered that the Newtonian laws of motion hold good for all motions whose velocity is such as to bring them within range of ordinary human experience, but do not for that reason, as Newton supposed, apply to all velocities whatever, but break down in the case of velocities approaching that of light.
Here, once more, it may be useful to notice that what is true of modern physics is a familiar feature of history. If an historian had no means of apprehending events that occupied more than an hour, he could describe the burning down of a house but not the building of a house; the assassination of Caesar but not his conquest of Gaul; the rejection of a picture by the hanging committee of the Royal Academy but not the painting of it; the performance of a symphony but not its composition. If two historians have each his own answer to the question: ‘What kinds of events happen, or can or might happen, in history?’ their answer would be extremely different if one habitually thought of an event as something that takes an hour and the other as something that takes ten years; and a third who conceived an event as taking anything up to 1,000 years would give a different answer again.
We can even say to some extent what kind of differences there would be. In general, making things takes longer than destroying them. The shorter our standard time-phase for an historical event, the more our history will consist of destructions, catastrophes, battle, murder, and sudden death. But destruction implies the existence of something to destroy; and as this type of history cannot describe how such a thing came into existence, for the process of its coming into existence was a process too long to be conceived as an event by this type of history, its existence must be presupposed as given, ready-made, miraculously established by some force outside history.
It would be rash for one who is not himself a natural scientist to venture an opinion as to how close the parallel is between what has just been said of history and anything in the science of nature. I have quoted the late Mr. Sullivan’s remark that the second law of thermodynamics applies only from the human point of view and would be unnecessary for an intelligent microbe. If the parallel of which I have spoken is at all close, an intelligent organism whose life had a longer time-rhythm than man’s might find it not so much unnecessary as untrue.
The natural processes that come most easily within ordinary human observation, it may be, are predominantly of a destructive kind, like the historical events that come most easily within the knowledge of the historian who thinks of an event as something that takes a short time. Like such an historian, the natural scientist, it may be, is led by this fact to think of events in nature as in the main destructive: releases or dissipations of energy stored he knows not how; to think of the natural world as running down like a clock or being shot away like a store of ammunition.
Such a conception of natural processes is not an invention of my own; it is one which we actually find stated over and over again in the writings of natural scientists in our own time. It very closely resembles a view of history which everyone knows to be long out of date: the view according to which historical processes are not constructive but merely destructive in character, with its corollary that what these processes destroy is a given, ready-made, miraculously established form of human life, a primitive Golden Age, concerning which all history can tell us how it has been progressively eroded by the tooth of time.
That view of history, as everyone knows, is an illusion. It is an illusion incidental to what, perhaps, may be called historical myopia: the habit of seeing short-phase historical events and not seeing those whose time-rhythm is longer. That history is a process in which tout casse, tout lasse, tout passe, is doubtless true; but it is also a process in which the things that are thus destroyed are brought into existence. Only it is easier to see their destruction than to see their construction, because it does not take so long.
May it not be the same in the world of nature? May it not be the case that the modern picture of a running-down universe, in which energy is by degrees exchanging a non-uniform and arbitrary distribution (that is, a distribution not accounted for by any laws yet known to us, and therefore in effect a given, ready-made, miraculously established distribution, a physicist’s Golden Age) for a uniform distribution, according to the second law of thermodynamics, is a picture based on habitual observation of relatively short-phase processes, and one destined to be dismissed as illusory at some future date, when closer attention has been paid to processes whose time-phase is longer? Or even if these long-phase processes should continue to elude human observation, may it not be found necessary to dismiss the same picture as illusory because, according to the principles of evolutionary physics, we shall find ourselves obliged to postulate such processes even though we cannot directly observe them?
| Last Updated: 10/19/22 |