FOOTNOTES:
[8] First Principles, § 46.
[9] Mill, Inductive Logic, bk. iii. ch. xii. p. 549.
[10] Ibid.
[11] First Principles, ch. iii. § 46.
[12] Seth, Chambers's Encyclopædia, s.v. "Philosophy."
[13] Kirchoff, Vorlesungen über mathematische Physik, i. p. 1.
[14] Mertz, History of European Thought in the Nineteenth Century, i. pp. 382, 3, note.
[15] Lotze, Microcosmus, E. T., ii. p. 718.
[16] Lotze, Microcosmus, E. T., ii. p. 718.
[17] Mill, Inductive Logic, bk. iii. ch. vi.
[18] Mill, Inductive Logic, bk. iii. ch. vi.
[19] Claude Bernard, quoted in L'Année Sociologique, première année.
[20] Principles of Biology, v. § 30.
[21] Principles of Sociology, vol. i. part ii.
[22] Ibid., § 260.
[23] First Principles, § 127.
[24] Ibid., § 153.
VII.
NECESSITY
We have seen that if material things can alone be treated of by science, if things which can be seen and handled are alone amenable to the methods of science, then there can be no science of mind, and no scientific laws to regulate mental phenomena. In the same way, if the field of evolution is completely filled by the redistribution of matter and motion, then there is no room left in the theory of evolution in which to accommodate the history of ideas or of morals, there is no evolution of thought or morality, no continuity between higher and lower in the intellectual development of man and the brute.
We may admit that the methods of mental and moral science, of sociology and political economy, are not identical with those employed by physics or chemistry or astronomy. But we cannot admit that the facts which, if not the proper study of mankind, are at any rate of the greatest interest to man, are not subject to or part of the process of evolution, and cannot be reduced to scientific law and order. The methods of the philosophical sciences may not be the same as those of the exact sciences; but neither are the methods of chemistry those of astronomy—just as the instruments of the astronomer are not those of the chemist. The exactness which is attained by those sciences that can apply the methods of mathematics to their subject-matter cannot be rivalled by philology or psychology. But it is not to all the material sciences that the mathematical methods can be applied: meteorology deals with matter in motion, but not yet with exactitude. The intangible and invisible, but none the less real, facts of our mental and moral experience can be measured to some extent by the statistics and averages and curves employed by the sociologist, the demographer, and political economist: the intensity of a desire may be estimated roughly and relatively by the "effective demand" for its object, the will to live by the number of suicides.
Again, we may admit that the laws of the exact or material sciences do not extend to mental science, without thereby forfeiting the right to subject mental phenomena to scientific investigation and analysis. Chemistry does not cease to be a science because chemical affinity cannot be exhibited as a case of the gravitation formula. Need psychology renounce the claim to be a science because the laws of the association of ideas cannot be deduced, say, from the laws of motion?
Of course, if science has no other object than to describe with mathematical accuracy the exact way in which material things move, if no method is scientific which does not result in such a formula, and if no generalisation, however true, is scientific which does not formulate motion in space, then, indeed, it is unscientific to talk of the evolution of mind and thought, of man and of society.
On the other hand, the movements of material things in space are facts of which we are aware, phenomena of which we are aware through our senses; in a word, they are sense-phenomena. We are aware of them as existing simultaneously and in combination, or as succeeding one upon another; and no truth, even of the most mathematical and exact of the sciences, does, or can do, more than express with mathematical exactness the precise conditions under which these sense-phenomena co-exist or follow one another, or the precise conditions without which such co-existence or sequence cannot take place. A mathematical science dealing with material things states only and always that certain sense-phenomena occur invariably and uniformly under certain conditions. The exact sciences move within the limits of the Uniformity of Nature and the law of Universal Causation; and their subject-matter consists of sense-phenomena, i.e. of things which, as known to science, are objects of perception to some mind.
But sense-phenomena are not the only mental phenomena of which we are aware: there are ideas which we do not see or handle, or smell or taste, but of which we are nevertheless distinctly conscious. Thought has its movement, ideas have their co-existence and sequences, the association of ideas has its laws. There is a uniformity of human nature as well as of external nature; there are conditions under which certain actions are always performed, and without which they would never be done. Whether the body of propositions in which these conditions are formulated be accorded or denied the name of science, matters little. But it is difficult to see what are the so great differences between these phenomena and sense-phenomena that make the latter amenable and the former insusceptible to scientific treatment. Is it that ideas are invisible? So is weight, yet the gravitation formula is scientific. Is it that thought is impalpable? So is colour, so is sound—yet there are optics and acoustics.
Be this as it may, what makes things material susceptible to scientific treatment is a quality which is not peculiar to them, but which is shared by them in common with things immaterial: it is that they are objects of which the mind is immediately aware, phenomena present to some consciousness, and that they are phenomena which appear in consciousness as co-existent and successive in certain definite uniform modes which can be detected by thought and formulated in general propositions, or laws.
If the theory of evolution comprehends all things, mind and morals as well as matter and motion; if the law of continuity connects all things together, immaterial as well as material, in a process which moves without break or interruption; it is because all things agree in the fact that they are presented (whether in sense or in idea) to the mind, and because they are presented in the continuity of consciousness.
But the object of the scientific mind is not to observe and record all the phenomena presented to it in the continuity of consciousness. On the contrary, it neglects and rejects many; but always with a purpose, viz. that of ascertaining and describing, as precisely as possible, the conditions under which a given co-existence or sequence occurs (and therefore may be expected to recur) and without which it fails to occur. In other words, science assumes that everything has a cause, and that in accordance with the uniformity of nature what has happened once will happen again in the same circumstances; that a cause will, in the absence of counteracting causes, produce its effect. Without these assumptions science cannot treat of any subject: no department of knowledge can be dealt with scientifically if these assumptions are not admitted with regard to that department. On the other hand, if by the aid of these assumptions we are enabled to reduce any set of phenomena to law and order, our success is of itself sufficient ground for regarding the assumptions as warrantable and justifiable. For science, at any rate, the only question is whether as a matter of fact they do enable us to determine under what conditions given co-existences or sequences will ensue, or what conditions such a co-existence or sequence necessarily implies.
With regard to human activity, mental and physical, it is plain matter of fact that such uniformities of sequence and co-existence not only can be but are demonstrated to prevail; and the extension of the scientific principle of cause and effect to the domain of human will and action is scientifically justified. The comparative sciences which deal with man and his works and words—archæology, anthropology, philology—are perpetually engaged in demonstrating, with fresh proofs every day, the uniformity of human nature: in similar circumstances men have always behaved in similar ways. To satisfy the same needs, they have manufactured similar instruments at similar stages of development: flint arrow-heads from Mexico or Japan resemble those taken from British barrows; the pottery of early Greece is hard to distinguish from that of Peru; the purpose of many stone implements of unknown antiquity has been discovered by a comparison of the use to which similar tools are put by savages still existing. That man's words, as well as his works, exhibit law, order, and uniformity in their growth, as well as in their phonetic decay, is shown by the science of comparative philology. That in the face of the same problems similar analogies have been used to produce similar solutions, is revealed by comparative mythology: the imagination, which might have seemed most free to throw off the trammels of law and of monotonous uniformity, falls in similar circumstances into very similar grooves.
If the will of man is not revealed in the things which he makes, in the words which he speaks, and the thoughts which he thinks, it is difficult to know where to look for its manifestation. If, on the other hand, it is manifested in these ways, then, whether it be free or not, it is clearly uniform in its action; and the extension to it of the law of causation seems fully justified by the results.
The recognition of the universality of the law of causation must not, however, be supposed to carry with it any implication that there are no differences between, say, the organic and inorganic, or that the laws of the one are identical with or deducible from those of the other; the association of ideas may be a scientific and established fact, and yet not obey the same laws as the adhesiveness of material substances. What unites all things into a continuous, coherent, and systematic cosmos, into a scientific whole, is first the fact that, whether phenomena in sense or phenomena in idea, they are all objects of thought; and next the fact that they all exhibit the universality of causation and the uniformity of nature.
Whether this uniformity which binds man and nature into one consistent whole is a uniformity of will or a uniformity of necessity, is quite another question. It is a metaphysical and not a scientific inquiry; and the metaphysical answer, whatever it may be, is one for which science does not and need not pause. So long as nature is granted to be uniform, it matters not to science whether the uniformity is of necessity or is freely willed. In either case the sequences or co-existences described by science will continue, under the circumstances described, to happen as described.
It is, however, commonly assumed that actions which are uniform are, by their very uniformity, proved to be necessitated; and that unless what happens was bound to happen, there can be no uniformity and no science. Hence on the one hand the recognition of the freedom of the will has been denounced as fatal to all scientific conceptions of human nature; while on the other hand the uniformity of human nature and action has been denied as being inconsistent with the freedom of the will. The one side has pointed to one set of facts, which prove irresistibly that men do will the same thing under the same circumstances. The other side has pointed to the equally undeniable fact of our consciousness of freedom.
The essential feature in our consciousness of freedom is our conviction that in the present we can do or abstain from doing a contemplated action, and in the past, though we did the thing, we might have abstained from it or have done something else. Now, whether this possibility that what took place might not have taken place is a real one or only a delusion, matters not to science. If real and true, it is indeed fatal to one particular metaphysical theory, viz. that every event which ever occurred was bound to occur and could not have happened otherwise; but it leaves every truth of science, every one of those concise descriptions of what takes place under given circumstances, absolutely intact. The freedom of the will is anathematised in the name but not in the interests of science.
That becomes clear when we reflect that the laws of science are, and do not pretend to be more than, hypothetical statements. The gravitation formula does not state that bodies do as a matter of fact actually fall at the rate of sixteen feet in the first second, and so on. The statement, if made, would be untrue: a feather floats much more slowly to the ground. Still less does the formula affirm that all bodies move towards each other—and for a very good reason: many bodies are at rest. The formula makes no definite statement as to what actually does occur: it merely states what would or will happen under certain circumstances; and it is doubly or trebly hypothetical. First, it asserts conditionally that if, and only if, bodies are free to move, they will tend to move towards each other at the rate of sixteen feet in the first second, and so on. Next, even if this condition be fulfilled in a particular case, and a given body is free to move, say, towards the earth, the law of gravitation does not assert that the body will absolutely, or unconditionally, or of necessity fall sixteen feet in the first second: it only affirms that the body tends to move at that rate, and the word "tends" conveys in its meaning a second hypothesis. What is meant by saying that a body tends to fall, or tends to move in a straight line, is simply that the body will fall or move in the direction or at the rate mentioned, provided that nothing happens to prevent it. The law of gravitation then, like every other law of science, from the very terms in which it is stated, contains two hypotheses: if bodies are free to move, then they tend to move at a certain rate. Further, like every other law of science, it is based on a third hypothesis, which, as it is assumed by all scientific laws, is not expressly referred to by any. That third hypothesis is that nature is uniform: if a body is free to move it will, in the future as in the past, tend to move at a certain rate, provided that nature is uniform.
Now, throughout all this, it is obvious that science knows nothing about "necessity." Indeed, it is obvious that science, by the trebly hypothetical form of all its laws, has taken particular pains to avoid prejudging the question whether what happens was bound to happen. As we have already said, science takes care to frame its statements in such a way that they are quite independent of metaphysical theory, and will remain as true within their limits if the theory of necessity prove erroneous as they will if it turns out to be correct.
Nor can it be said, thus far, that the laws of science lead us to the theory of necessity as their logical conclusion. It may be true that if I walk over a precipice I shall fall to the bottom, in accordance with the law of gravitation. But it does not logically follow that therefore I must walk over. It may be true that a suspension bridge will fall in the same way, if the supports be removed; but it does not follow that they are therefore bound to give way. It may be true that if nature is uniform certain sequences will happen; but it does not therefore follow that nature must be uniform. In other words, the theory of necessity, if true, cannot be based on science, but must rely on some metaphysical considerations. Science does not undertake to prove even that nature is uniform, much less that it is uniform of necessity. The opposite theory, that the uniformity of nature or of human nature is due to the action of a will freely manifesting itself as uniform, may be considered superfluous from the scientific point of view. But the theory of necessity from the same point of view is equally superfluous. As long as events do happen uniformly, science has all she wants—whether their uniformity is of will or of necessity is for her quite a superfluous question. And if science were all that man wanted, these rival metaphysical theories would be of no interest to him either. But the persistency of the attempt to extract some support for the metaphysical theory of necessity out of the facts of science shows that men of science, being men, must have their metaphysics.
Are there, then, other facts of science, or assumptions essential to science, which require the metaphysical theory of necessity as their presupposition or entail it as their natural consequence? Probably the reply will be that there is one such principle: that of the Universality of the Law of Causation. The assumption that everything must have a cause may be on the part of science a pure assumption, and one which, like the Uniformity of Nature, cannot be proved by science; but it does, it may be said, assume the existence of a necessity in things.
It does, it may be replied, but whether the necessity which science assumes is the same as that maintained by the metaphysical theory in question, may be doubted. The metaphysical theory is that everything which happens happens of necessity, and could not have happened otherwise than it did. The assumptions which science makes with regard to causation are that nothing can happen unless the conditions requisite to its production are fulfilled, and that when those conditions are present the result necessarily follows. The question is whether this scientific necessity is the same as that metaphysical necessity; or, if they are not the same, whether either is a logical consequence from the other.
They are not the same: the scientific assumption is hypothetical, the metaphysical absolute. The former says that things will happen in one way, if certain conditions are fulfilled, in another if they are not; the latter that they absolutely must happen in this way, and not in that; and that it is an illusion to imagine that they can happen either this way or that. Science allows us the alternative; the metaphysical theory declares that the alternative is an impossibility or an illusion. The metaphysical theory may be right, but it is not the same thing as the scientific assumption. Neither can it be exhibited as a logical presupposition of or consequence from the scientific assumption. From a hypothetical "if" you cannot logically get an absolute "must." It may be a scientific truth that, if an electric spark is passed through two atoms of hydrogen and one of oxygen, a drop of water will be formed. But it does not follow that therefore an electric spark must be passed through them.
It is obvious that the difference between science and metaphysics in the matter of necessity is that, whereas science cautiously says, "If certain conditions are fulfilled, certain results will ensue," metaphysics boldly says, "The conditions on which the whole future depends are already absolutely fixed." Once more, this metaphysical theory may be true; but, if so, it is not from science that it derives its truth. The transition from the "if" of science to the "must" of metaphysics is illogical, though not unnatural, and is facilitated by a certain amount of obscurity, which can be thrown over it by drawing illustrations from the past. Thus, if an event has already taken place, we may infer with certainty from the fact of its occurrence that the conditions necessary to produce it were realised. And as each of those conditions must have had a cause, we can infer again that the conditions requisite to produce them were fulfilled. And so we may travel back ad infinitum along a never-ending chain of cause and effect, always moving from one fixed and necessitated event to another event equally necessitated and fixed. Thus the whole past history of the universe may be exhibited as a necessary sequence of events; and the inference may be drawn, and for the purposes of the theory of metaphysical necessity must be drawn, that because the occurrence of an event proves that the conditions required for its production were realised, therefore they and they alone were bound to be realised. Yet this is simply our old familiar non sequitur thrown into the past tense. It is true that if I walk over a precipice I shall fall, according to the law of gravitation. But I am not therefore bound to walk over. It is true that the man who fell over the cliff obeyed the law of gravity. But we cannot infer either from the law of gravitation or from the fact of his falling that he was bound to fall. We can infer that the conditions requisite to produce the fall were present, but we cannot infer from the fall that they were bound to be present. It may be quite true that they were bound to be present, but the effect which followed on them cannot be alleged either as the cause or the proof of such necessity. We must look for the reason of the necessity—if there be any necessity in the case—elsewhere. Shall we, then, say that the conditions of the fall were themselves effects of prior causes, without which they would not have happened? That again is true, but the fact that Z would not have happened had not Y preceded, is not in itself any proof that Y was bound to happen. And so we may travel back ad infinitum along the never-ending chain of cause and effect without ever finding ourselves in a position to infer from the law that everything must have a cause, that this cause was bound to operate rather than that. The occurrence of Z is no proof that Y was bound to happen, nor is the fact that Y really happened any proof that its cause X was bound to occur—and so we may work back to the beginning of the alphabet. The fact that B took place shows that A actually occurred, but not that A, rather than A1 or A2, was bound to occur. And if A is the beginning, what was the nature of the necessity (prior to the beginning of things) which determined in favour of A rather than A1 or A2?
We may indeed say, if we like—since no one can prevent us from saying things without proof or probability—that the mere fact that A happened shows that it was bound to happen. But then we might just as well have said it of Z, and saved ourselves the trouble of going through so much alphabet to get so little result. We might just as well say that as the explosion or the accident did happen as a matter of fact, it could not possibly have been prevented: Z was bound to happen under the circumstances, therefore the circumstances could not have been altered; only one result was possible under the conditions, therefore no other conditions were possible.
Or—to go back to the beginning of the alphabet once more—we may say with science that we are content with the fact that A did happen, or, since science does not profess to take us back to an absolute beginning (force and matter being eternal and without beginning), let us say we may, like science, be content with the fact that K can be shown to have happened; but whether K, rather than K1 or K2, was bound to occur there is nothing in science to show. If we take up this, the scientific, attitude, two consequences follow. First, there is nothing in science to require or countenance the metaphysical theory of necessity. Next, what is true of K is equally true of L or M or Z. The fact that L or M or Z occurred proves that the conditions did combine in the way necessary to produce L or M or Z, not that they were bound to combine in that way and could not have combined so as to produce L1 or L2, or Z1 or Z2 or Z3.
Perhaps it may be said that the following is the proper way of stating the case: We have reason for believing that, as a matter of scientific necessity, if L is at work it can only produce M, and not M1 or M2 (the application of a light to a barrel of gunpowder can have only one result). But L was at work, therefore M alone could result. Quite true, but that does not show that the light was bound to be applied, or that the powder might not have been damp. In fine, the moment the conditions requisite for the explosion are combined, the explosion is necessary, M is the only possible result; but until then the explosion is not necessary, and the result may be M1, or M2, or M3. A cause (i.e. the conditions combined) can only have one effect; but until it has that effect it is not the cause, and may never be. Pre-existent causes, which must inevitably produce predetermined effects, are figments of the metaphysical imagination. Conditions which may, and, subject to the trebly hypothetical laws of science, will combine in certain ways are scientific facts.
In fine, the Uniformity of Nature, in the sense in which Nature is assumed, both by science and by common sense, to be uniform, simply amounts to the assumption that under the same conditions the same consequences will ensue. But this uniformity neither requires nor entails necessity. The very form chosen by science for the expression of scientific laws proclaims the fact: "If bodies are free to move," "if counteracting causes be absent," "a body tends to move in the same straight line." Whatever necessity is introduced into the truths of science thus expressed is obviously imported from without, and is no part of science. We may, if we choose, read necessity into science, but there is no warrant in science for doing so. Science is absolutely without prejudice on this point. If everything that happens happens of necessity, the gravitation formula will receive no accession to its truth. If there be no necessity in the case, each and every truth of science remains valid as long as the same consequences do ensue in the same circumstances.
Since, then, science observes an armed neutrality in this dispute, and is concerned only to guard that assumption of the uniformity of nature which is vital to her existence, we must turn elsewhere for a decision of the question.
We began this chapter with an expression of our full adhesion to the view which insists upon the uniformity, not merely of nature, but also of human nature. We rejected the idea that there is no science of man, and has been no evolution of mind, as a patent absurdity, and a violent contradiction of admitted facts. Any theory of evolution and any definition of science which fails to comprehend human nature is thereby condemned as inadequate and inaccurate. For those, then, who with us accept the continuity and uniformity between nature and man there will be no difficulty in arguing from the one to the other: which of the two we shall start from will depend mainly upon circumstances, upon which is the more accessible in any particular inquiry, and which is likely to afford the best "take-off." In the present case the action of inanimate objects upon one another can be accounted for on either hypothesis, i.e. that such action is willed by some superior power or that it is necessitated by some previous action, which is necessitated by some other previous action, and so on for ever, without ever reaching any original or originating necessity. Both hypotheses will fit all the facts of all the physical sciences; both are hypotheses; and science can do and does do without either one or the other. Nor does our observation of the observed facts of nature enable us to say, with regard to any actual fact of this kind, either that it could or that it could not have happened otherwise than it did. In fine, as long as we confine ourselves to the subject-matter of the physical sciences, as long as we start in this case from nature, we cannot find anything to disturb the equal balance of the two hypotheses, which are two hypotheses and nothing more. But when we turn from nature to human nature, when we consult our own experience of our own actions, the case is notoriously different. Our experience in that case is that of two or more suggested and possible actions we are free to choose whichever we will; and our memory of past acts of choice testifies that though we actually chose one particular course, we might have abstained from it in favour of some other alternative. Here, too, as in the case of purely physical causation, the fact that a thing happened is proof conclusive that, in accordance with the law of universal causation, the conditions necessary to its occurrence were fulfilled; but it constitutes no proof or probability that the conditions were bound to be fulfilled. The fact that we chose to act in a certain way does not in the least convince us that we were bound to choose that action and that action alone. On the contrary, our memory is clear and our conviction is certain that our choice was free. In the physical and the spiritual spheres alike it is true that, when all the conditions requisite for a given effect are combined, the result must ensue. And in both spheres it is equally true that until the conditions are effectively combined no such necessity exists. In the case of our own actions we are directly and immediately conscious of the fact that it is our own will which effects this combination. For us, therefore, who hold, with Professor Huxley, that the uniformity and continuity of nature with human nature is essential to any rational and scientific view of the universe and to every comprehensive theory of evolution, it is natural to interpret physical by spiritual causation. We know from direct and personal experience of certain cases of causation that, though a particular effect necessarily ensued from a certain combination of conditions, the conditions might have been combined differently and with a different result. There is, therefore, nothing unreasonable in the inference that with regard to the events in nature the conditions which produced them might have combined differently and with different results; and that the determining factor was a will (not our own) conscious of its own freedom.
Thus far, then, the case stands thus, that in the observed facts of nature there is nothing to incline the balance in favour either of Necessity or Free-will; and that if those facts constituted the whole of our experience we should have no reason to believe the one rather than the other. But when we turn to the consideration of events of which we are the cause, we know that our contribution to the sum of conditions on which the event depends is a free-will offering which we make or decline to make as we like. That consideration would not in itself be sufficient to warrant us in inferring a similar absence of necessity in the combination of the conditions which produce natural events. If, for instance, we had reason to believe or evidence to show an absolute chasm between nature and human nature, an impossibility of their being subject to any common laws or conceptions; or if, like primitive man or the savage, we had not the accumulated observations of science to demonstrate the truth of evolution and the law of continuity—then we should have no reason or little reason, as the case might be, for interpreting nature's action and human action by one another.
The savage, as is well known, does, without any scientific authority whatever, assume straight off an entire uniformity of nature with human nature. He jumps at conclusions: he takes it for granted that everything which moves has a will of its own, like himself. But though the savage shares with the savant the impulse to believe in an essential continuity binding together man and nature, that impulse is about all they have in common. In the savage it expresses itself in an absolute identification, entirely ignoring all differences, between the two: the tree or the river has to be a conscious, rational creature, though its behaviour bears more difference from than resemblance to that of a human being. In the savant, the same impulse is trained to fertility by being constantly subjected to the guidance of observed facts: man as an animal organism is subject to the same physiological laws as other similar organisms; as an organic compound, to the same chemical changes; as a body possessing inertia, to the same physical laws. The savant's belief, however, in the continuity of nature and human nature is consistent with or rather implies points of difference between the two; e.g. man possesses a consciousness which the river does not, man is, the river is not, a conscious cause. Great though these differences be, still they are not in the eyes of science and from the point of view of evolution great enough to constitute a breach of continuity, for human actions are with the growth of science increasingly seen to be part of the uniformity of nature: the human cause only produces its effect provided that all the requisite conditions are forthcoming. Indeed, there is a danger, in some tendencies of modern thought, of ignoring the differences and of confounding continuity with identity. The distinction between the animate and the inanimate, which was hardly reached by the savage, is in danger of being overlooked by the modern materialist—an error which would be paralleled in religion by a relapse from monotheism into nature-worship. And as in the pathology of religion there is a constant tendency to substitute for religious faith a trust in the automatic efficacy of rites and ceremonies, which is a falling away into mere magic, so in metaphysic there is a tendency, in the name of science falsely invoked, to substitute for the actions of agents consciously free the operation of an automatic and magical necessity. Freedom of the will is constantly taken, or rather mistaken, both by its supporters and opponents, to mean the power of acting without a motive, and to imply that from identically the same combination of conditions one result can ensue at one time and quite a different one at another; and freedom of the will in this sense, and with this implication, is rightly rejected as inconsistent with the uniformity of nature. Freedom, however, means not the absence of motive, but the presence of more motives than one, for where there is no alternative there is no freedom, and where there is an alternative there is a choice between two things. The fact that conscious action is always action with a motive has nothing in it repugnant to the uniformity of nature, unless uniformity of nature is arbitrarily assumed to be identical with necessity. Nor has the uniformity of nature, i.e. the fact that the same action issues from the same combination of conditions, anything in it inconsistent with the freedom of the will, unless the occurrence of an event proves that it was bound to occur. The laws of science—whether physical science or mental and moral science—are hypothetical statements: if the love of gain predominates in men, then all the consequences predicted by the science of Political Economy will ensue. But this proves neither that the love of gain must nor even that it does prevail. The uniformity which marks the actions of men as often as this motive prevails is sufficient for the purposes of science, and is consistent with the freedom of the will; it does not imply that men act without a motive, nor that the same conditions produce now one effect and now another. Until the conditions which are necessary for the production of a physical event are effectively combined, physical science knows no necessity to make them combine in that particular way; if they combine in some other way, and with some other result, that combination will equally illustrate the truth of science (which says, if A then B, if A1 then B1), and the result will equally accord with the uniformity of nature. The same considerations apply to human nature, and if applied will be found consistent with the freedom of the will. Until the mind is made up, i.e. so long as there are alternative courses open to it, the man is free, just in the same way as in physical science, until the combination of conditions is effected, the result may or may not follow. If one alternative is adopted one set of consequences will ensue, if another, another; but whichever is adopted the results will be in accordance with the uniformity of nature, the law of cause and effect will not have been violated, the mind will not have acted without a motive, or under the influence of necessity. In fine, the universality of the law of causation lies in the fact that, however the conditions combine, each combination can only produce its peculiar effect; and whatever effect occurs can be the result only of its appropriate conditions. To say with the necessitarian that, unless at the beginning of things the course of events was unalterably fixed once and for ever, there can be no science, is to deny the universality of the laws of science, to maintain that they are true only of one particular succession of events, and would not be true of any other. In point of fact, however, the laws of science, by their hypothetical form, are adapted to cope with what is at least as striking as the uniformity of nature, that is, the diversity of nature: they apply not merely to one, but to all possible combinations of circumstances. In what way a body will move depends upon the conditions at work; but Science is not such a maimed and crippled thing that she refuses to consider its motion until she has been assured that, of the various conceivable conditions that might be brought to bear on the body, only one can, as a matter of fact, be brought to bear. On the contrary, the universality of her laws lies in the fact that they apply to all possible combinations, not merely to combination A producing B, but to A1 producing B1, A2 producing B2, and so on. The origin of all terrestrial life may be traced back, let us say, to the fortuitous combination of chemicals which constituted the first speck of protoplasm; and sundry important consequences can be shown by science to have flowed from that fortuitous concurrence. The origin of any particular species may be traced back to the accidental appearance of a sport or variety which happened to be better adapted to the environment than the parent forms were.
But, if these accidental and fortuitous occurrences had not taken place, the subsequent course of things upon earth, though there might have been no life, would still have been just as much in accordance with the uniformity (and the diversity) of nature, and equally amenable to scientific explanation. The theory that the first speck of protoplasm or the ancestral variety of a species was bound by a metaphysical necessity to occur just when and where it did, is of no use to science: if A had not happened, A1 or A2 or A3 would have done, and the resulting B or B1 or B2 or B3 would have been equally in accordance with the uniformity of nature and equally explicable by science.
If, then, in the physical world neither science nor the uniformity of nature requires us to believe in necessity, there is no antecedent presumption that necessity must be the law of the spiritual world: we may examine the facts of our own inner experience without prejudice. What the freedom of the will implies is that the mind has present to it more alternatives or motives than one, and that they are real alternatives and real motives, i.e. motives which may really in this particular case influence action, alternatives any one of which may be adopted in this case. The circumstances or conditions in which a man makes up his mind are, until he has made up his mind, so to speak, held in solution, and may be precipitated this way or that at his choice, or not precipitated at all, unless he chooses. The fact that in the same circumstances the same result ensues is no argument against the freedom of the will, if it be remembered that the will is itself one of the circumstances which contribute to the result, just as the mass of a body, as well as the force applied to it, helps to determine its velocity. The statement of the case then becomes this: if all the circumstances of the case be the same, and the will be the same, the consequences (i.e. the determination of the will) also will be the same. But the necessitarian position requires the statement that if all the circumstances be the same, then without any further proviso the will is determined by the circumstances; or, to put it another way, that the will does not in any way contribute to the result, which is just as though we were to say that the mass of a body had nothing to do with its velocity. But if the will does contribute to the result, i.e. to the determination of itself, it is in part self-determining.
That there must be some circumstances present, if there is to be any self-determination on the part of the will, we have already admitted; the freedom of the will implies the presence of more alternatives or motives than one—and we always have the alternative of acting or abstaining from action. But this admission only limits the powers of the will; it does not lessen its liberty. The mind can only choose between the alternatives offered to it; but as long as it has real alternatives it is free. That there must be definite circumstances if there is to be any definite determination of the will is in accordance with the fact that a cause is not some one individual thing, but a sum of conditions, every one of which is necessary to the effect, and the absence of any one of which is enough to prevent the occurrence of the result. It is a vulgar error to single out some one of the conditions (e.g. the force acting on a body) and dub it the cause, to the neglect of all the other conditions (e.g. the body's mass) which are equally necessary to the effect. It is the error committed by the necessitarian who calls the circumstances the cause, in the case of a determination of the will, and neglects the part played by the will itself.
This point of view illustrates the untenability of another objection to the freedom of the will, viz. that it implies that under the same conditions different results can ensue, or, to put it in other words, that without any change in the conditions either this or that consequence may issue. Freedom of the will is thus alleged to be inconsistent with the uniformity of nature, with the law that a cause must produce its effect. The fallacy here obviously lies in assuming that, in a modification of the will, the circumstances by themselves constitute the cause, whereas in point of fact the cause consists of the sum of the conditions, i.e., in this case, of the circumstances and the will taken in combination. Alter any one of the conditions, and the effect will be changed—whether the condition which is changed be one of the circumstances or be the will, matters not. Conversely, if under the same circumstances a man acts one way one time and another another, the inference is not that the uniformity of nature has been violated, and that the same conditions produce different effects, but that one of the conditions was different; and as ex hypothesi the circumstances (i.e. all the conditions except the will) were in this case the same, it remains that the condition which was different in this case was the will.
Really, it is the theory of necessity which violates the uniformity of nature, for it requires us to believe that provided certain of the conditions (viz. all the circumstances except the will) are the same, then the result must be the same, no matter how much the remaining condition (the will) changes. We may, indeed, evade this conclusion by simply denying that the will is one of the conditions of its own modifications, and we may say that the wax contributes nothing to the form which it takes on when impressed by the seal. The truth is that if the will or the wax appears in the result, it must have been present and active as one of the conditions: it contributes to its own determination, and is in part self-determining.
If it be in accordance with the uniformity of nature and with our experience of what actually happens, that the circumstances should be the same and the will different on two different occasions, then the theory of necessity breaks down: if we can will and act differently under the same circumstances, we have all the freedom we want. But if—all the circumstances, save the will, being the same—the resulting modification or determination of the will is different, then the difference of result must be due to some difference in the conditions; all the conditions save one were ex hypothesi the same; the remaining condition, therefore, viz. the will, must have changed. What caused the change? Not the circumstances: one attempt to explode a barrel of gunpowder may resemble another in all the circumstances save one (the dampness of the powder), but the circumstances which remain the same (application of the spark, etc.) are not the cause of the difference in the remaining condition.
If, then, we do as a matter of fact at times under the same circumstances will different things, and if the circumstances are not the cause of the change of will, then the will changes itself, i.e. is self-determining, self-modifying. And, as we all know from experience, it determines itself at the moment of choice, not before. Until all the conditions requisite for the effect are combined, neither physical nor mental science requires us to assume that they must combine in this particular way—that the light must be applied to the powder because an explosion will take place if it is applied, that the motive of gain must be adopted because it will be gratified if it is obeyed.
Whether the conditions combine so as to produce A, or so as to produce B, the uniformity of nature is equally obeyed in either case, the law that a cause must produce its effect is equally fulfilled, and either sequence is as amenable to scientific explanation as the other. But though science and the uniformity of nature both require us to believe that when the conditions are combined the result will follow, neither requires us to assume that the combination is fixed before it is effected. And this is true equally of purely physical events and of human actions. This truth, in the case of the latter class of actions, is expressed by the statement that alternative courses of action are open to the agent, and that they are real alternatives, alternatives such that any one of them may in this particular instance be followed. From the point of view of science and of the uniformity of nature, we do not conceive that there is any difference in this respect between human actions and physical events: if science is to include both kinds of sequence and to render a rational account of them, we must assume that the principles on which conditions combine or fail to combine are the same in both cases. If physical events and human actions are both constituents in the process of evolution, there must be a continuity between them. It follows, therefore, that, in the case of physical events as well as of human actions, until the conditions are combined in such a way as to involve one determinate result to the exclusion of all others, they might combine in other ways with other results—in fine, that before the combination is effected there are always other alternatives.
At this point it becomes necessary to take into account the diversity as well as the uniformity of nature—in this case a diversity which will lead us to a higher uniformity. To the human agent alternative courses of action are open in the sense that he is conscious of their possibility and that after deliberation he adopts one or other of them. With purely physical phenomena and material things the case is different: they may be combined in this way or in that; the alternative is indeed open, so long as the combination is not effected, but it is not open to them nor is it adopted, when adopted, by them. It is adopted for them. In some cases by man. In all cases by that by which alone alternative courses of action can be contemplated and adopted—a conscious will. The course and form which man imparts to material things—to his implements or his works of art—make them so far the expression of his will; for the rest they are equally an expression of will, though of a will not his.
For those at the present day who unfeignedly accept the general principles of evolution and philosophise from them, a dualistic philosophy is impossible. They cannot hold that matter is subject to evolution and that mind is not; and the continuity of the process of evolution forbids us to suppose that there is any real discontinuity between that which appears at one stage as matter and at another as mind. There is no discontinuity if material things (i.e. the things of which we have sense-perception, but which differ from our sensations in being permanent) are on the one side the permanent expressions of Will and on the other are the transient impressions made on us in the shape of sense-phenomena.
What is true thus of the content of evolution, of that which is in process of evolution, is true also of the law of the process. We cannot suppose that it extends only to matter—that the behaviour of matter is susceptible of a rational explanation and the behaviour of mind is not. The continuity of the process excludes the possibility of a dual control: either the power which manifests itself in all things is intelligent throughout or it is not. If there is no reason in the behaviour of things, but only necessity, then those human actions and conceptions which man considers to be the result of his reason are really the result of unintelligent necessity.
It is the latter hypothesis which is expressed by the necessitarian theory. The ordinary belief of mankind—a belief which it is impossible to resist at the moment when you are making up your mind whether you will do this or not—is that you can do the thing or not, that the alternatives are real and the motives such that either of them may be acted on. The necessitarian hypothesis is that the alternatives are not real, that even before you have made up your mind there is only one alternative which you can follow—the other courses are only apparent alternatives, because you cannot choose or act on any of them; the other motives are not real motives, because by a necessity dating from the beginning of things they cannot possibly influence you on this occasion. Your action is as automatic as that of a piano which responds to the touch. The difference is that you think about the stimulus received and the piano does not. Consequently the piano makes no mistakes; you make two. You think of various possible consequences of the stimulus—which are all impossible—and you imagine that the one which you choose is the consequence of your intelligent choice, whereas it is the automatic outcome of that iron law of necessity which binds together the whole process of evolution.
It will be readily understood that a hypothesis of this kind, which is apparently in violent conflict with the plainest facts of our daily personal experience, and gives the lie to that consciousness of freedom which we all possess, would not be held in theory—it cannot be acted on in practice—unless it appeared to be the consequence of some well-established facts. It is, of course, held by its supporters to be a logical consequence from the uniformity of nature and the law of universal causation, and to be a necessary pre-supposition if we are to give any scientific account of human nature and its evolution. If, as we have argued at length in this chapter, that is not the case, if the law of universal causation only requires that a thing cannot take place unless the requisite conditions combine—and not that conditions, which did or may combine, were or are bound to combine—the question still remains, what if any value the hypothesis has on its own intrinsic merits.
In the first place it is a hypothesis which can never either be proved or disproved. The hypothesis is that our supposed consciousness of freedom is an illusion, that if we imagine we are free to choose what we will do, or that we could in the past have chosen otherwise than we did, we are deceived. The hypothesis is not based on any facts of consciousness: it is a suggestion that consciousness may be deceptive. It may: there is no means of proving or disproving the suggestion, for any reply must proceed from one consciousness to another, both of which are suspected by the maker of the suggestion to be not wholly trustworthy. We cannot ask him to concede to us, in order that we may convince him by argument, the very point which is in dispute.
In the next place, the hypothesis of necessity does formally account for all the facts which it is designed to explain: it accounts for the whole process of evolution. If everything that happens does so because it must, then the mere occurrence of any step in the process carries its own explanation with it: the mere fact that it occurred shows that it was bound to occur. If we ask, "Why was it bound to occur?" the answer is, "Because it was." Various intermediate reasons may be interpolated—because everything must have a cause, and every cause must have its effect—but if we ask, "Why must everything have a cause? why must every cause produce its effect?" the ultimate answer is always, "It must because it must." If we ask, "What proof is there that it must?" there is none. As we have already said, the hypothesis is one which does not admit either of proof or disproof.
The case is much the same with the opposite theory of freedom. Formally, the hypothesis that the whole process of evolution is throughout the expression of self-determining will is adequate to account for all the facts. But it is a hypothesis which can be neither proved nor disproved if the testimony of consciousness to our freedom may not be accepted. We cannot prove that the testimony of consciousness is true or to be trusted in this or any other matter. We take it on faith. The questions arise, therefore, Is it reasonable to take anything on faith? and if so, what? and why?
VIII.
INSUFFICIENT EVIDENCE
The theory of Design is singularly tenacious of existence, as many errors and all truths are. Science still speaks of "organs," that is of "tools" (ὄργανα), and of organs as performing "functions"; for the fact remains that organs are the instruments by means of which the organism acts, and that they have each their appropriate work to do, their function to perform, though science may decline to draw the inference that the instruments were designed to perform the work they do.
The Argument from Design was a comparatively simple affair as long as the organism and the environment were assumed to have been separately created: you had only to show how marvellously and perfectly they fitted one another when brought together, and it followed that they must have been designed to fit—to say they only chanced to fit was obviously absurd. But when science discovered that organism and environment were not thus independent of one another, the marvel vanished: if the environment shaped the organism, or the organism modified the environment to suit itself, no wonder that they fitted one another. It ceases to be remarkable that rivers should always flow by great cities, when we reflect that men selected sites near rivers. And chance seemed to have been established by Evolution where Design once reigned; for, if the only forms of life which can flourish in a given spot are those which are suited to the place, all we can say is that, if one form is fit to survive, it will; and if it is not, some other will. Whatever form survives will do so, not because it was designed to do so, but because it happened to be suited to its surroundings. In fine, organisms and their organs are what they are because circumstances and their past history have made them so: they have been evolved, not designed.
A little reflection, however, is enough to show that the Argument from Design is not completely excluded by evolution: things in general are what circumstances and their past history have made them; but were not those very circumstances designed to evolve what they did? Nay, are we not compelled to assume that they were so designed, if we believe in a Designer?
If, however, we ask Natural Science to discuss these questions with us, she declines the invitation on the ground that it is not her business to do so: her business is to find out in what way, not with what purpose, animal life has come to assume the various forms in which we know it; and she can do this, her business, quite well—indeed better—without discussing such questions. If it were proved that the history of animal life upon this earth had been intended from the beginning to follow the lines on which it has actually developed, not one of the problems which Natural Science has yet to solve would be brought a whit nearer solution; nor would she be any the better off, if it were proved that there was no design. She therefore very properly declines to discuss the question: there may be a Design and a Designer, or there may not; she does not know; if it is the business of science to answer the question, it must be of some other science, not of Natural Science.
So too Physical Science, when asked whether the laws of motion and matter were not designed to produce the effects which they actually do cause, replies that they may or may not, but that the law of gravitation, for instance, is equally true for her purposes, whether bodies were or were not designed to fall to the earth at the rate of sixteen feet in the first second, and so on. It may be the business of some other science to answer such questions: it is not the business of Physical Science.
And so the inquirer may go the round of the whole family of Sciences. It is an extraordinarily industrious family. It has an enormous amount of work to do: it has to feed, clothe, and generally provide for all mankind. And it can only carry on at all by a very careful division of labour: each science has her allotted task, and can only get the day's work done in the day by strictly confining herself to that task. Each science has her own questions to answer, and can only succeed in doing so by refusing to listen to any others.
The inquirer may think it strange that, in all this vast and active organisation for answering questions, no provision should be made for answering what seem to him to be some of the most important questions of all; and if he has been brought up really to believe in science, he will think it too strange to be true; he will persist with his questions, and will be eventually rewarded for his faith by discovering that there is a science which undertakes to answer them—Theology. But he will also discover that Theology is not very cordially esteemed by her sister sciences—not that they are jealous of her because she has the presumption to profess to answer questions which they acknowledge to be too high for them, but because there are grave suspicions as to her legitimacy: it is doubted whether she is a Science at all. She is, they are afraid it must be admitted, untruthful, immoral, and certainly altogether unscientific: she says what she cannot prove, and says she believes it. But they know she only pretends to believe it: they, of course, do not believe anything on insufficient evidence; what hypocrisy, then, to pretend that anyone can really believe anything except what is proved by scientific methods! They are thankful to say that they have no "faith." However, she may improve; she is certainly very backward; still, she may grow up into a common-sense science like her sisters; and then she will give up the foolish idea that she can answer questions which they cannot.
And now what truth is there in the picture thus drawn?
If there be a God, there is no other fact in the world of such awful or such blessed import to man. Religion is based on faith that there is a God. To tell the religious mind that there is no scientific proof of the existence of God is to tell it nothing new. Those were not the terms on which we took up our faith—that we should have scientific proof of everything before we did anything. On the contrary, religion begins when, and only when, a man begins "to walk humbly with his God," to know that he knows nothing except that his soul cleaves to God and humbly trusts in Him. We do not bargain so much belief, and no more, for so much proof: we give "ourselves, our souls and bodies." The gift is free. The soul shrinks from saying even that it has proof of God's existence; it only knows it hopes and longs for Him. "Faith is the assurance of things hoped for," and the strength of our assurance is as the strength of our hope. But scientific proof is not the thing hoped for: it is not what is desired when the soul is conscious of but one thing, that it thirsteth, like the hart after the water-brooks, for the living God. The humble confession of our illimitable ignorance is the foundation of our faith and will ever be its sure refuge, its inexpugnable stronghold. It is only when, being ignorant, we are tempted to deny our ignorance, that trouble begins. We drop the substance for the shadow when we believe not in God, but in some proof of God.
To the man of science all this talk about faith appears mere folly, sheer unreason, a morbid wallowing in ignorance from pure love of ignorance; and there are others who, whilst admitting that proof is not what is wanted by some minds, yet are aware, from their own sad experience, that other minds yearn for it, and can know no peace without it. And if we ask what kind of proof it is that they require, the answer is plain: it is the same kind as science insists on. Then let us go to the man of science and wait at his door: he at any rate is not ignorant, and we, if ignorant, at least are willing to learn. That he should rather look down upon us is only what might be expected in a man who by sheer force of reason has discovered the sole source of truth and built up the whole fabric of science. Certainly, when he has taken us over his palace and shown us its marvels—the balances he uses to weigh the sun, the plates with which he photographs invisible stars, the cinematographic pictures of the earth's past history, his forecasts of the future of the solar system—we are not merely willing but eager to learn how it is all done. And when we come to know him, we find that in spite of the marvels, all of his own making, by which he is surrounded, he is not puffed up, as he might have been: indeed he is, he assures us, only an ordinary man. "Scientific investigation is not, as many people seem to suppose, some kind of modern black art."[25] It is simply plain, ordinary common sense, consistently applied; and, above all, persistently declining to accept anything without sufficient evidence. In ordinary life, says the man of science, we do not swallow any statement that anybody chooses to make—we ask for some evidence; and if science waxes every day, and religion wanes, it is merely because science has made it the rule of her being never to believe anything without sufficient evidence, and religion has not.
Naturally, then, we wish to know what is "sufficient evidence" in the eyes of science, since everything, we are told, depends on that. The reply is brief: whatever is based on the Uniformity of Nature has sufficient evidence. If we are inclined to be puzzled by the "Uniformity of Nature," we are soon reassured; it is literally the most ordinary thing in the world, there is no difficulty about it. Man is born into a world in which changes are unceasingly taking place. Some things change even as the clouds shift—every second, and in a way patent to all beholders. Others change imperceptibly and with great slowness, as e.g. the level of the dry land or the shape of the coast-line. But all things change, πάντα ῥεῖ. Nothing abideth long in one stay. It is these changes which bring all things good to man, and also all things ill. If, then, man is to survive, he must learn to evade the latter changes, which threaten to crush him, and he must be there in time to profit by the former. Such was the problem presented to primitive man, and such it still is for every one of us to-day: the successful man is the one who is beforehand with the world, and, if he is beforehand it is because he has learned to read the signs of the times and the seasons. In a word, he has learned to recognise that changes are not always mere chances, that some changes are uniformly preceded by certain others, and may consequently be foreseen. In the beginning the changes that man can forecast are few indeed: his prevision is no greater than the brute's. The child does not foresee that fire will burn; he learns by experience. And whatever man can forecast, he has learned it all by experience. It is a slow way of learning, it has taken man thousands upon thousands of years to learn what he knows now; still he has learned to know the causes of countless things, to control the causes and to anticipate the effects of many. But more important, more valuable than all his experience and all his knowledge of what produces what, of what uniformly precedes or follows what, is the final and comprehensive truth which at last he reaches, that nothing happens arbitrarily, that everything in nature is uniform. That, the Uniformity of Nature, is the great truth in which all others are summed up: to its establishment have gone the labours of all past generations of mankind, to its support the whole experience of the race contributes. It is the truth of truths, the test of truth: whatsoever is established on it shall not be shaken, whatever contravenes it shall not endure.
The Uniformity of Nature is the base not only of all science, but of every act of reason in the most commonplace affairs of ordinary life; and, though you may not know it, you assume it every moment. Why are you sure that the sun will rise to-morrow? Because Nature is uniform. Why do you know that fire will burn? Because Nature is uniform. Why that all men are mortal? Why that a cause will always produce its effect? Because of the Uniformity of Nature. For each and all of these beliefs the evidence is sufficient; it is the Uniformity of Nature. How different, says the man of science, is the procedure of science, that is of common sense, from the unscientific methods of theology! Why do we believe that the earth will bring forth her kindly fruits in due season? Because it is God's will? That is a hypothesis; it may be true or it may not; it cannot be proved or disproved; there is no evidence against it, but there is no evidence for it. Very different is the answer of science and common sense: it is that the earth will produce crops in accordance with certain natural causes, mechanical and chemical. That also is a hypothesis which may or may not be true. Yes, but it is one for which there is some evidence—the Uniformity of Nature. In the same way, if anyone were to say that the result of the next general election depended not on the electors but on the planets, we should decline to believe him, because there is no evidence to show that the planets have anything to do with it, and there is good evidence for believing that the votes of the electors have. In fine, the teaching of science is: demand sufficient evidence for everything, and always remember that by sufficient evidence is meant the Uniformity of Nature.
This sounds so simple and so convincing that we are tempted to try it. But first let us make sure that we have learned our lesson properly. In the course of long ages mankind has slowly accumulated enough experience to warrant the confident belief that Nature is uniform. Now, primitive man was of course a savage, and knew nothing of the Uniformity of Nature; he therefore could not have had sufficient evidence for believing anything in his experience. But it is on the accumulation of such experiences—every one of which we must reject because they were not based on the Uniformity of Nature—that our belief in the Uniformity of Nature is supposed to rest. In other words, it is based on them and they were based on nothing. This result of acting strictly up to the principle of not suffering anything to pass without sufficient evidence seems somewhat discouraging, until the man of science comes to our rescue and reminds us that just as we, without knowing it, have acted all our lives on the tacit assumption that Nature is uniform, so did primitive man; and that consequently there really was sufficient evidence and scientific proof for the savage's experiences, though of course he could not have framed it in words; and so, the bases of the Uniformity of Nature are really quite sound. But even now we are not altogether out of our difficulties, for granted that the savage, like ourselves, tacitly assumed Nature to be uniform, was there sufficient evidence for the assumption? and if so, what was the evidence? It could not be the Uniformity of Nature, because that is just the question; and, if it was anything else, it was not sufficient evidence.
It really seems rather difficult to get sufficient evidence for the axiom, viz. the Uniformity of Nature, on which the whole of science is built. And yet we must have sufficient evidence for it, or else we shall have to conclude that Science has no more logical foundation than Religion.
But once more the man of science comes to our assistance and explains that in the beginning, before the Uniformity of Nature is proved, it is only probable that what has once happened will happen again in similar circumstances, and at first perhaps not very probable; but when wider and wider experience still shows that what has once happened does actually happen again under the same circumstances, the Uniformity of Nature becomes more and more probable, until at last, if not actually proved, it is still the most probable hypothesis that we possess or can possess: "our highest and surest generalisations remain on the level of justifiable expectations; that is, very high probabilities."[26]
Now, with all respect to logicians like John Stuart Mill, and men of science like Huxley, we must point out that this begs the whole question. If we assume that Nature is uniform, then it is probable that what has often happened will happen again. But if we do not assume that Nature is uniform, then the repeated occurrence of a thing does not make it in the least probable that it will occur again. To assume without proof that Nature is uniform is to ask us to accept a statement without evidence, which, if we have learnt the lesson of science, we can hardly do. On the other hand, if we begin with the admission that Nature may or may not be uniform, but that, to begin with, we no more know whether it will actually prove to be uniform than we know whether a penny, when we are about to toss it, will fall head or tail; then, according to the mathematical theory of probability, it matters not how many times you toss the penny, the chances next throw are exactly the same as they were at the first throw—it matters not how many times Nature has proved uniform in the past, she is no more likely to prove uniform to-morrow than she was on the first of days. If it is really an open question at the beginning whether Nature is or is not uniform, it remains an open question to the end. The man of science need not admit that it is an open question, if he does not want to do so; but if he does admit it, then let him stick to it throughout; and let him reflect that if he begins by admitting it and ends by denying it, he has but gradually retracted his own free admission, and unconsciously been betrayed into denying what he began by admitting to be true.
The fact of the matter is that the axioms of science—the Uniformity of Nature and the Law of Universal Causation—not only are not proved by what experience we have had of them, but "cannot be proved by any amount of experience."[27] Not only can they not be proved by any amount of experience, they are incapable of being demonstrated at all: "they are neither self-evident nor are they, strictly speaking, demonstrable."[28] If, then, they are not and cannot be proved either by experience or in any other way, on what does the man of science ground his belief in them? On Faith. "The ground of every one of our actions, and the validity of all our reasonings, rest upon the great act of faith, which leads us to take the experience of the past as a safe guide in our dealings with the present and the future."[29]