Now, as the law of causality is known to us à priori, and is therefore a transcendental law, applicable to every possible experience and consequently without exception, as will be shown in § 21; as moreover it decides, that upon a given, definite, relatively first state, a second equally definite one inevitably ensues by rule, i.e., always; the relation between cause and effect is a necessary one, so that the causal law authorizes us to form hypothetical judgments, and thereby shows itself to be a form of the principle of sufficient reason, upon which principle all judgments must be founded and, as will be shown further on, all necessity is based.
This form of our principle I call the principle of the sufficient reason of becoming, because its application invariably pre-supposes a change, the entering upon a new state: consequently a becoming. One of its essential characteristics is this: that the cause always precedes the effect in Time (compare § 47), and this alone gives us the original criterion by which to distinguish which is cause and which effect, of two states linked together by the causal nexus. Conversely, in some cases, the causal nexus is known to us through former experience; but the rapidity with which the different states follow upon each other is so great, that the order in which this happens escapes our perception. We then conclude with complete certitude from causality to succession: thus, for instance, we infer that the igniting of gunpowder precedes its explosion.[63]
From this essential connection between causality and succession it follows, that the conception of reciprocity, strictly speaking, has no meaning; for it presumes the effect to be again the cause of its cause: that is, that what follows is at the same time what precedes. In a "Critique of Kantian Philosophy," which I have added to my chief work, and to which I refer my readers,[64] I have shown at length that this favourite conception is inadmissible. It may be remarked, that authors usually have recourse to it just when their insight is becoming less clear, and this accounts for the frequency of its use. Nay, it is precisely when a writer comes to the end of his conceptions, that the word 'reciprocity' presents itself more readily than any other; it may, in fact, be looked upon as a kind of alarm-gun, denoting that the author has got out of his depth. It is also worthy of remark, that the word Wechselwirkung, literally reciprocal action—or, as we have preferred translating it, reciprocity—is only found in the German language, and that there is no precise equivalent for it in daily use in any other tongue.
From the law of causality spring two corollaries which, in virtue of this origin, are accredited as cognitions à priori, therefore as unquestionable and without exception. They are, the law of inertia and that of permanence of substance. The first of these laws avers, that every state in which a body can possibly be—consequently that of repose as well as that of any kind of movement—must last for ever without change, diminution, or augmentation, unless some cause supervenes to alter or annul it. But the other law, by which the eternity of Matter is affirmed, results from the fact, that the law of causality is exclusively applicable to states of bodies, such as repose, movement, form, and quality, since it presides over their temporal passing in or out of being; but that it is by no means applicable to the existence of that which endures these states, and is called Substance, in order precisely to express its exemption from all arising and perishing. 'Substance is permanent' means, that it can neither pass into, nor out of being: so that its quantity existing in the universe can neither be increased nor diminished. That we know this à priori, is proved by the consciousness of unassailable certainty with which, when we see a body disappear—whether it be by conjuring, by minute subdivision, by combustion, volatilisation, or indeed any process whatever—we all nevertheless firmly assume that its substance, i.e. its matter, must still exist somewhere or other in undiminished quantity, whatever may have become of its form; likewise, when we perceive a body suddenly in a place, where it was not before, that it must have been brought there or formed by some combination of invisible particles—for instance, by precipitation—but that it, i.e. its substance, cannot have then started into existence; for this implies a total impossibility and is utterly inconceivable. The certainty with which we assume this beforehand (à priori), proceeds from the fact, that our Understanding possesses absolutely no form under which to conceive the beginning and end of Matter. For, as before said, the law of causality—the only form in which we are able to conceive changes at all—is solely applicable to states of bodies, and never under any circumstances to the existence of that which undergoes all changes: Matter. This is why I place the principle of the permanence of Matter among the corollaries of the causal law. Moreover, we cannot have acquired à posteriori the conviction that substance is permanent, partly because it cannot, in most instances, be empirically established; partly also, because every empirical knowledge obtained exclusively by means of induction, has only approximate, consequently precarious, never unconditioned, certainty. The firmness of our persuasion as to this principle is therefore of a different kind and nature from our security of conviction with regard to the accuracy of any empirically discovered law of Nature, since it has an entirely different, perfectly unshakable, never vacillating firmness. The reason of this is, that the principle expresses a transcendental knowledge, i.e. one which determines and fixes, prior to all experience, what is in any way possible within the whole range of experience; but, precisely by this, it reduces the world of experience to a mere cerebral phenomenon. Even the most universal among the non-transcendental laws of Nature and the one least liable to exception—the law of gravitation—is of empirical origin, consequently without guarantee as to its absolute universality; wherefore it is still from time to time called in question, and doubts occasionally arise as to its validity beyond our solar system; and astronomers carefully call attention to any indications corroborative of its doubtfulness with which they may happen to meet, thereby showing that they regard it as merely empirical. The question may of course be raised, whether gravitation takes effect between bodies which are separated by an absolute vacuum, or whether its action within a solar system may not be mediated by some sort of ether, and may not cease altogether between fixed stars; but these questions only admit of an empirical solution, and this proves that here we have not to do with a knowledge à priori. If, on the other hand, we admit with Kant and Laplace the hypothesis, as the most probable one, that each solar system has developed out of an original nebula by a gradual process of condensation, we still cannot for a moment conceive the possibility of that original substance having sprung into being out of nothing: we are forced to assume the anterior existence of its particles somewhere or other, as well as their having been brought together somehow or other, precisely because of the transcendental nature of the principle of the permanence of Substance. In my Critique of Kantian Philosophy,[65] I have shown at length, that Substance is but another word for Matter, the conception of substance not being realisable excepting in Matter, and therefore deriving its origin from Matter, and I have also specially pointed out how that conception was formed solely to serve a surreptitious purpose. Like many other equally certain truths, this eternity of Matter (called the permanence of substance) is forbidden fruit for professors of philosophy; so they slip past it with a bashful, sidelong glance.
By the endless chain of causes and effects which directs all changes but never extends beyond them, two existing things remain untouched, precisely because of the limited range of its action: on the one hand, Matter, as we have just shown; on the other hand, the primary forces of Nature. The first (matter) remains uninfluenced by the causal nexus, because it is that which undergoes all changes, or on which they take place; the second (the primary forces), because it is they alone by which changes or effects become possible; for they alone give causality to causes. i.e. the faculty of operating, which the causes therefore hold as mere vassals a fief. Cause and effect are changes connected together to necessary succession in Time; whereas the forces of Nature by means of which all causes operate, are exempt from all change; in this sense therefore they are outside Time, but precisely on that account they are always and everywhere in reserve, omnipresent and inexhaustible, ever ready to manifest themselves, as soon as an opportunity presents itself in the thread of causality. A cause, like its effect, is invariably something individual, a single change; whereas a force of Nature is something universal, unchangeable, present at all times and in all places. The attraction of a thread by amber, for instance, at the present moment, is an effect; its cause is the preceding friction and actual contact of the amber with the thread; and the force of Nature which acts in, and presides over, the process, is Electricity. The explanation of this matter is to be found in my chief work,[66] and there I have shown in a long chain of causes and effects how the most heterogeneous natural forces successively come into play in them. By this explanation the difference between transitory phenomena and permanent forms of operation, becomes exceedingly clear; and as, moreover, a whole section (§ 26) is devoted to the question, it will be sufficient here to give a brief sketch of it. The rule, by which a force of Nature manifests itself in the chain of causes and effects—consequently the link which connects it with them—is the law of Nature. But the confusion between forces of Nature and causes is as frequent as it is detrimental to clearness of thought. It seems indeed as though no one had accurately defined the difference between these conceptions before me, however great may have been the urgency for such a distinction. Not only are forces of Nature turned into causes by such expressions as, 'Electricity, Gravity, &c., are the cause of so-and-so,' but they are even often turned into effects by those who search for a cause for Electricity, Gravity, &c. &c., which is absurd. Diminishing the number of the forces of Nature, however, by reducing one to another, as for instance Magnetism is in our days reduced to Electricity, is a totally different thing. Every true, consequently really primary force of Nature—and every fundamental chemical property belongs to these forces—is essentially a qualitas occulta, i.e. it does not admit of physical, but only of metaphysical explanation: in other words, of an explanation which transcends the world of phenomena. No one has carried this confusion, or rather identification, of causes with forces of Nature further than Maine de Biran in his "Nouvelles considérations des rapports du physique au moral," for it is essential to his philosophy. It is besides remarkable, that when he speaks of causes, he rarely uses the word cause alone, but almost always speaks of cause ou force, just as we have seen Spinoza above (§ 8) write ratio sive causa no less than eight times in the same page. Both writers are evidently conscious that they are identifying two disparates, in order to be able to make use of the one or the other, according to circumstances; for this end they are obliged to keep the identification constantly before their readers' mind.—
Now Causality, as the director of each and every change, presents itself in Nature under three distinct forms: as causes in the strictest acceptation of the word, as stimuli, and as motives. It is just upon this difference that the real, essential distinction between inorganic bodies, plants, and animals is based, and not upon external, anatomical, let alone chemical, distinctions.
A cause, in its narrowest sense, is that upon which changes in the inorganic kingdom alone ensue: those changes, that is to say, which form the theme of Mechanics, Physics, and Chemistry. Newton's third fundamental law, "Action and reaction are equal to one another," applies exclusively to this cause, and enunciates, that the state which precedes (the cause) undergoes a change equivalent to that produced by it (the effect). In this form of causality alone, moreover, does the degree of the effect always exactly correspond to the degree of the cause, so as to enable us accurately to calculate the one by means of the other.
The second form of causality is the stimulus; it reigns over organic life, as such, i.e. over plant life and the vegetative, that is, the unconscious, part of animal life. This second form is characterized by the absence of the distinctive signs of the first. In it accordingly action and reaction are not equal, nor does the intensity of the effect by any means correspond throughout all its degrees to the intensity of the cause; in fact, the opposite effect may even be produced by intensifying the cause.
The third form of causality is the motive. Under this form causality rules animal life proper: that is, the exterior, consciously performed actions of all animals. The medium for motives is knowledge: an intellect is accordingly needed for susceptibility to motives. The true characteristic of the animal is therefore the faculty of knowing, of representing (Das Vorstellen). Animals, as such, always move towards some aim and end, which therefore must have been recognised by them: that is to say, it must have presented itself to them as something different from themselves, yet of which they are conscious. Therefore the proper definition of the animal would be: 'That which knows;' for no other definition quite hits the mark or can even perhaps stand the test of investigation. Movement induced by motives is necessarily wanting where there is no cognitive faculty, and movement by stimuli alone remains, i.e. plant life. Irritability and sensibility are therefore inseparable. Still motives evidently act in a different way from stimuli; for the action of the former may be very brief, nay, need only be momentary; since their efficacy, unlike that of stimuli, stands in no relation whatever to the duration of that action, to the proximity of the object, &c. &c. A motive needs but to be perceived therefore, to take effect; whereas stimuli always require outward, often even inward, contact and invariably a certain length of time.
This short sketch of the three forms of causality will suffice here. They are more fully described in my Prize-essay on Free Will.[67] One thing, however, still remains to be urged. The difference between cause, stimulus, and motive, is obviously only a consequence of the various degrees of receptivity of beings; the greater their receptivity, the feebler may be the nature of the influence: a stone needs an impact, while man obeys a look. Nevertheless, both are moved by a sufficient cause, therefore with the same necessity. For 'motivation'[68] is only causality passing through knowledge; the intellect is the medium of the motives, because it is the highest degree of receptivity. By this, however, the law of causality loses nothing whatever of its rigour and certainty; for motives are causes and operate with the same necessity which all causes bring with them. This necessity is easy to perceive in animals because of the greater simplicity of their intellect, which is limited to the perception of what is present. Man's intellect is double: for not only has he intuitive, but abstract, knowledge, which last is not limited to what is present. Man possesses Reason; he therefore has a power of elective decision with clear consciousness: that is, he is able to weigh against one another motives which exclude each other, as such; in other terms, he can let them try their strength on his will. The most powerful motive then decides him, and his actions ensue with just the same necessity as the rolling of a ball after it has been struck. Freedom of Will[69] means (not professorial twaddle but) "that a given human being, in a given situation, can act in two different ways." But the utter absurdity of this assertion is a truth as certain and as clearly proved, as any truth can be which passes the limits of pure mathematics. In my Essay on Free Will, to which the Norwegian Society awarded the prize, this truth is demonstrated more clearly, methodically, and thoroughly than has been done before by anyone else, and this moreover with special reference to those facts of our consciousness by which ignorant people imagine that absurdity to be confirmed. In all that is essential however, Hobbes, Spinoza, Priestley, Voltaire, and even Kant[70] already taught the same doctrine. Our professional philosophers, of course, do not let this interfere with their holding forth on Free Will, as if it were an understood thing which had never been questioned. But what do these gentlemen imagine the above-named great men to have come into the world for, by the grace of Nature? To enable them (the professors) to earn their livelihood by philosophy?—Since I had proved this truth in my prize-essay more clearly than had ever been done before, and since moreover a Royal Society had sanctioned that proof by placing my essay among its memoranda, it surely behoved these worthies, considering the views they held, to make a vigorous attack upon so pernicious a doctrine, so detestable a heresy, and thoroughly to refute it. Nay, this duty was all the more imperative as, in my other essay "On the Foundation of Morality,"[71] I had proved the utter groundlessness of Kant's practical Reason with its Categorical Imperative which, under the name of the Moral Law, is still used by these gentlemen as the corner-stone of their own shallow systems of morality. I have shown it to be a futile assumption so clearly and irrefutably, that no one with a spark of judgment can possibly believe any longer in this fiction.—"Well, and so they probably did."—Oh no! They take good care not to venture on such slippery ground! Their ability consists in holding their tongues; silence is all they have to oppose to intelligence, earnestness, and truth. In not one of the products of their useless scribblings that have appeared since 1841, has the slightest notice been taken of my Ethics—undoubtedly the most important work on Moral Philosophy that has been published for the last sixty years—nay, their terror of me and of my truth is so great, that none of the literary journals issued by Academies or Universities has so much as mentioned the book. Zitto, zitto, lest the public should perceive anything: in this consists the whole of their policy. The instinct of self-preservation may, no doubt, be at the bottom of these artful tactics. For would not a philosophy, whose sole aim was truth, and which had no other consideration in view, be likely to play the part of the iron pot among the earthen ones, were it to come in contact with the petty systems composed under the influence of a thousand personal considerations by people whose chief qualification is the propriety of their sentiments? Their wretched fear of my writings is the fear of truth. Nor can it be denied, that precisely this very doctrine of the complete necessity of all acts of the will stands in flagrant contradiction with all the hypotheses of their favourite old-woman's philosophy cut after the pattern of Judaism. Still, that severely tested truth, far from being disturbed by all this, as a sure datum and criterion, as a true δός μοι ποῦ στῶ, proves the futility of all that old-woman's philosophy and the urgent need of a fundamentally different, incomparably deeper view of the Universe and of Man;—no matter whether that view be compatible with the official duties of a professional philosopher or not.