And as this determination of time is, always and in all its parts, a quant.i.ty, the perception produced is to be considered as a quant.i.ty which proceeds through all its degrees--no one of which is the smallest possible--from zero up to its determined degree. From this we perceive the possibility of cognizing a priori a law of changes--a law, however, which concerns their form merely. We merely antic.i.p.ate our own apprehension, the formal condition of which, inasmuch as it is itself to be found in the mind antecedently to all given phenomena, must certainly be capable of being cognized a priori.
Thus, as time contains the sensuous condition a priori of the possibility of a continuous progression of that which exists to that which follows it, the understanding, by virtue of the unity of apperception, contains the condition a priori of the possibility of a continuous determination of the position in time of all phenomena, and this by means of the series of causes and effects, the former of which necessitate the sequence of the latter, and thereby render universally and for all time, and by consequence, objectively, valid the empirical cognition of the relations of time.
C. THIRD a.n.a.lOGY.
Principle of Coexistence, According to the Law of Reciprocity or Community.
All substances, in so far as they can be perceived in s.p.a.ce at the same time, exist in a state of complete reciprocity of action.
PROOF.
Things are coexistent, when in empirical intuition the perception of the one can follow upon the perception of the other, and vice versa--which cannot occur in the succession of phenomena, as we have shown in the explanation of the second principle. Thus I can perceive the moon and then the earth, or conversely, first the earth and then the moon; and for the reason that my perceptions of these objects can reciprocally follow each other, I say, they exist contemporaneously. Now coexistence is the existence of the manifold in the same time. But time itself is not an object of perception; and therefore we cannot conclude from the fact that things are placed in the same time, the other fact, that the perception of these things can follow each other reciprocally. The synthesis of the imagination in apprehension would only present to us each of these perceptions as present in the subject when the other is not present, and contrariwise; but would not show that the objects are coexistent, that is to say, that, if the one exists, the other also exists in the same time, and that this is necessarily so, in order that the perceptions may be capable of following each other reciprocally.
It follows that a conception of the understanding or category of the reciprocal sequence of the determinations of phenomena (existing, as they do, apart from each other, and yet contemporaneously), is requisite to justify us in saying that the reciprocal succession of perceptions has its foundation in the object, and to enable us to represent coexistence as objective. But that relation of substances in which the one contains determinations the ground of which is in the other substance, is the relation of influence. And, when this influence is reciprocal, it is the relation of community or reciprocity. Consequently the coexistence of substances in s.p.a.ce cannot be cognized in experience otherwise than under the precondition of their reciprocal action. This is therefore the condition of the possibility of things themselves as objects of experience.
Things are coexistent, in so far as they exist in one and the same time.
But how can we know that they exist in one and the same time? Only by observing that the order in the synthesis of apprehension of the manifold is arbitrary and a matter of indifference, that is to say, that it can proceed from A, through B, C, D, to E, or contrariwise from E to A. For if they were successive in time (and in the order, let us suppose, which begins with A), it is quite impossible for the apprehension in perception to begin with E and go backwards to A, inasmuch as A belongs to past time and, therefore, cannot be an object of apprehension.
Let us a.s.sume that in a number of substances considered as phenomena each is completely isolated, that is, that no one acts upon another.
Then I say that the coexistence of these cannot be an object of possible perception and that the existence of one cannot, by any mode of empirical synthesis, lead us to the existence of another. For we imagine them in this case to be separated by a completely void s.p.a.ce, and thus perception, which proceeds from the one to the other in time, would indeed determine their existence by means of a following perception, but would be quite unable to distinguish whether the one phenomenon follows objectively upon the first, or is coexistent with it.
Besides the mere fact of existence, then, there must be something by means of which A determines the position of B in time and, conversely, B the position of A; because only under this condition can substances be empirically represented as existing contemporaneously. Now that alone determines the position of another thing in time which is the cause of it or of its determinations. Consequently every substance (inasmuch as it can have succession predicated of it only in respect of its determinations) must contain the causality of certain determinations in another substance, and at the same time the effects of the causality of the other in itself. That is to say, substances must stand (mediately or immediately) in dynamical community with each other, if coexistence is to be cognized in any possible experience. But, in regard to objects of experience, that is absolutely necessary without which the experience of these objects would itself be impossible. Consequently it is absolutely necessary that all substances in the world of phenomena, in so far as they are coexistent, stand in a relation of complete community of reciprocal action to each other.
The word community has in our language [Footnote: German] two meanings, and contains the two notions conveyed in the Latin communio and commercium. We employ it in this place in the latter sense--that of a dynamical community, without which even the community of place (communio spatii) could not be empirically cognized. In our experiences it is easy to observe that it is only the continuous influences in all parts of s.p.a.ce that can conduct our senses from one object to another; that the light which plays between our eyes and the heavenly bodies produces a mediating community between them and us, and thereby evidences their coexistence with us; that we cannot empirically change our position (perceive this change), unless the existence of matter throughout the whole of s.p.a.ce rendered possible the perception of the positions we occupy; and that this perception can prove the contemporaneous existence of these places only through their reciprocal influence, and thereby also the coexistence of even the most remote objects--although in this case the proof is only mediate. Without community, every perception (of a phenomenon in s.p.a.ce) is separated from every other and isolated, and the chain of empirical representations, that is, of experience, must, with the appearance of a new object, begin entirely de novo, without the least connection with preceding representations, and without standing towards these even in the relation of time. My intention here is by no means to combat the notion of empty s.p.a.ce; for it may exist where our perceptions cannot exist, inasmuch as they cannot reach thereto, and where, therefore, no empirical perception of coexistence takes place.
But in this case it is not an object of possible experience.
The following remarks may be useful in the way of explanation. In the mind, all phenomena, as contents of a possible experience, must exist in community (communio) of apperception or consciousness, and in so far as it is requisite that objects be represented as coexistent and connected, in so far must they reciprocally determine the position in time of each other and thereby const.i.tute a whole. If this subjective community is to rest upon an objective basis, or to be applied to substances as phenomena, the perception of one substance must render possible the perception of another, and conversely. For otherwise succession, which is always found in perceptions as apprehensions, would be predicated of external objects, and their representation of their coexistence be thus impossible. But this is a reciprocal influence, that is to say, a real community (commercium) of substances, without which therefore the empirical relation of coexistence would be a notion beyond the reach of our minds. By virtue of this commercium, phenomena, in so far as they are apart from, and nevertheless in connection with each other, const.i.tute a compositum reale. Such composita are possible in many different ways. The three dynamical relations then, from which all others spring, are those of inherence, consequence, and composition.
These, then, are the three a.n.a.logies of experience. They are nothing more than principles of the determination of the existence of phenomena in time, according to the three modi of this determination; to wit, the relation to time itself as a quant.i.ty (the quant.i.ty of existence, that is, duration), the relation in time as a series or succession, finally, the relation in time as the complex of all existence (simultaneity).
This unity of determination in regard to time is thoroughly dynamical; that is to say, time is not considered as that in which experience determines immediately to every existence its position; for this is impossible, inasmuch as absolute time is not an object of perception, by means of which phenomena can be connected with each other. On the contrary, the rule of the understanding, through which alone the existence of phenomena can receive synthetical unity as regards relations of time, determines for every phenomenon its position in time, and consequently a priori, and with validity for all and every time.
By nature, in the empirical sense of the word, we understand the totality of phenomena connected, in respect of their existence, according to necessary rules, that is, laws. There are therefore certain laws (which are moreover a priori) which make nature possible; and all empirical laws can exist only by means of experience, and by virtue of those primitive laws through which experience itself becomes possible.
The purpose of the a.n.a.logies is therefore to represent to us the unity of nature in the connection of all phenomena under certain exponents, the only business of which is to express the relation of time (in so far as it contains all existence in itself) to the unity of apperception, which can exist in synthesis only according to rules. The combined expression of all is this: "All phenomena exist in one nature, and must so exist, inasmuch as without this a priori unity, no unity of experience, and consequently no determination of objects in experience, is possible."
As regards the mode of proof which we have employed in treating of these transcendental laws of nature, and the peculiar character of we must make one remark, which will at the same time be important as a guide in every other attempt to demonstrate the truth of intellectual and likewise synthetical propositions a priori. Had we endeavoured to prove these a.n.a.logies dogmatically, that is, from conceptions; that is to say, had we employed this method in attempting to show that everything which exists, exists only in that which is permanent--that every thing or event presupposes the existence of something in a preceding state, upon which it follows in conformity with a rule--lastly, that in the manifold, which is coexistent, the states coexist in connection with each other according to a rule, all our labour would have been utterly in vain. For more conceptions of things, a.n.a.lyse them as we may, cannot enable us to conclude from the existence of one object to the existence of another. What other course was left for us to pursue? This only, to demonstrate the possibility of experience as a cognition in which at last all objects must be capable of being presented to us, if the representation of them is to possess any objective reality. Now in this third, this mediating term, the essential form of which consists in the synthetical unity of the apperception of all phenomena, we found a priori conditions of the universal and necessary determination as to time of all existences in the world of phenomena, without which the empirical determination thereof as to time would itself be impossible, and we also discovered rules of synthetical unity a priori, by means of which we could antic.i.p.ate experience. For want of this method, and from the fancy that it was possible to discover a dogmatical proof of the synthetical propositions which are requisite in the empirical employment of the understanding, has it happened that a proof of the principle of sufficient reason has been so often attempted, and always in vain.
The other two a.n.a.logies n.o.body has ever thought of, although they have always been silently employed by the mind,* because the guiding thread furnished by the categories was wanting, the guide which alone can enable us to discover every hiatus, both in the system of conceptions and of principles.
[*Footnote: The unity of the universe, in which all phenomena to be connected, is evidently a mere consequence of the admitted principle of the community of all substances which are coexistent. For were substances isolated, they could not as parts const.i.tute a whole, and were their connection (reciprocal action of the manifold) not necessary from the very fact of coexistence, we could not conclude from the fact of the latter as a merely ideal relation to the former as a real one. We have, however, shown in its place that community is the proper ground of the possibility of an empirical cognition of coexistence, and that we may therefore properly reason from the latter to the former as its condition.]
4. THE POSTULATES OF EMPIRICAL THOUGHT.
1. That which agrees with the formal conditions (intuition and conception) of experience, is possible.
2. That which coheres with the material conditions of experience (sensation), is real.
3. That whose coherence with the real is determined according to universal conditions of experience is (exists) necessary.
Explanation.
The categories of modality possess this peculiarity, that they do not in the least determine the object, or enlarge the conception to which they are annexed as predicates, but only express its relation to the faculty of cognition. Though my conception of a thing is in itself complete, I am still ent.i.tled to ask whether the object of it is merely possible, or whether it is also real, or, if the latter, whether it is also necessary. But hereby the object itself is not more definitely determined in thought, but the question is only in what relation it, including all its determinations, stands to the understanding and its employment in experience, to the empirical faculty of judgement, and to the reason of its application to experience.
For this very reason, too, the categories of modality are nothing more than explanations of the conceptions of possibility, reality, and necessity, as employed in experience, and at the same time, restrictions of all the categories to empirical use alone, not authorizing the transcendental employment of them. For if they are to have something more than a merely logical significance, and to be something more than a mere a.n.a.lytical expression of the form of thought, and to have a relation to things and their possibility, reality, or necessity, they must concern possible experience and its synthetical unity, in which alone objects of cognition can be given.
The postulate of the possibility of things requires also, that the conception of the things agree with the formal conditions of our experience in general. But this, that is to say, the objective form of experience, contains all the kinds of synthesis which are requisite for the cognition of objects. A conception which contains a synthesis must be regarded as empty and, without reference to an object, if its synthesis does not belong to experience--either as borrowed from it, and in this case it is called an empirical conception, or such as is the ground and a priori condition of experience (its form), and in this case it is a pure conception, a conception which nevertheless belongs to experience, inasmuch as its object can be found in this alone. For where shall we find the criterion or character of the possibility of an object which is cogitated by means of an a priori synthetical conception, if not in the synthesis which const.i.tutes the form of empirical cognition of objects? That in such a conception no contradiction exists is indeed a necessary logical condition, but very far from being sufficient to establish the objective reality of the conception, that is, the possibility of such an object as is thought in the conception. Thus, in the conception of a figure which is contained within two straight lines, there is no contradiction, for the conceptions of two straight lines and of their junction contain no negation of a figure. The impossibility in such a case does not rest upon the conception in itself, but upon the construction of it in s.p.a.ce, that is to say, upon the conditions of s.p.a.ce and its determinations. But these have themselves objective reality, that is, they apply to possible things, because they contain a priori the form of experience in general.
And now we shall proceed to point out the extensive utility and influence of this postulate of possibility. When I represent to myself a thing that is permanent, so that everything in it which changes belongs merely to its state or condition, from such a conception alone I never can cognize that such a thing is possible. Or, if I represent to myself something which is so const.i.tuted that, when it is posited, something else follows always and infallibly, my thought contains no self-contradiction; but whether such a property as causality is to be found in any possible thing, my thought alone affords no means of judging. Finally, I can represent to myself different things (substances) which are so const.i.tuted that the state or condition of one causes a change in the state of the other, and reciprocally; but whether such a relation is a property of things cannot be perceived from these conceptions, which contain a merely arbitrary synthesis. Only from the fact, therefore, that these conceptions express a priori the relations of perceptions in every experience, do we know that they possess objective reality, that is, transcendental truth; and that independent of experience, though not independent of all relation to form of an experience in general and its synthetical unity, in which alone objects can be empirically cognized.
But when we fashion to ourselves new conceptions of substances, forces, action, and reaction, from the material presented to us by perception, without following the example of experience in their connection, we create mere chimeras, of the possibility of which we cannot discover any criterion, because we have not taken experience for our instructress, though we have borrowed the conceptions from her. Such fict.i.tious conceptions derive their character of possibility not, like the categories, a priori, as conceptions on which all experience depends, but only, a posteriori, as conceptions given by means of experience itself, and their possibility must either be cognized a posteriori and empirically, or it cannot be cognized at all. A substance which is permanently present in s.p.a.ce, yet without filling it (like that tertium quid between matter and the thinking subject which some have tried to introduce into metaphysics), or a peculiar fundamental power of the mind of intuiting the future by antic.i.p.ation (instead of merely inferring from past and present events), or, finally, a power of the mind to place itself in community of thought with other men, however distant they may be--these are conceptions the possibility of which has no ground to rest upon. For they are not based upon experience and its known laws; and, without experience, they are a merely arbitrary conjunction of thoughts, which, though containing no internal contradiction, has no claim to objective reality, neither, consequently, to the possibility of such an object as is thought in these conceptions. As far as concerns reality, it is self-evident that we cannot cogitate such a possibility in concreto without the aid of experience; because reality is concerned only with sensation, as the matter of experience, and not with the form of thought, with which we can no doubt indulge in shaping fancies.
But I pa.s.s by everything which derives its possibility from reality in experience, and I purpose treating here merely of the possibility of things by means of a priori conceptions. I maintain, then, that the possibility of things is not derived from such conceptions per se, but only when considered as formal and objective conditions of an experience in general.
It seems, indeed, as if the possibility of a triangle could be cognized from the conception of it alone (which is certainly independent of experience); for we can certainly give to the conception a corresponding object completely a priori, that is to say, we can construct it. But as a triangle is only the form of an object, it must remain a mere product of the imagination, and the possibility of the existence of an object corresponding to it must remain doubtful, unless we can discover some other ground, unless we know that the figure can be cogitated under the conditions upon which all objects of experience rest. Now, the facts that s.p.a.ce is a formal condition a priori of external experience, that the formative synthesis, by which we construct a triangle in imagination, is the very same as that we employ in the apprehension of a phenomenon for the purpose of making an empirical conception of it, are what alone connect the notion of the possibility of such a thing, with the conception of it. In the same manner, the possibility of continuous quant.i.ties, indeed of quant.i.ties in general, for the conceptions of them are without exception synthetical, is never evident from the conceptions in themselves, but only when they are considered as the formal conditions of the determination of objects in experience. And where, indeed, should we look for objects to correspond to our conceptions, if not in experience, by which alone objects are presented to us? It is, however, true that without antecedent experience we can cognize and characterize the possibility of things, relatively to the formal conditions, under which something is determined in experience as an object, consequently, completely a priori. But still this is possible only in relation to experience and within its limits.
The postulate concerning the cognition of the reality of things requires perception, consequently conscious sensation, not indeed immediately, that is, of the object itself, whose existence is to be cognized, but still that the object have some connection with a real perception, in accordance with the a.n.a.logies of experience, which exhibit all kinds of real connection in experience.
From the mere conception of a thing it is impossible to conclude its existence. For, let the conception be ever so complete, and containing a statement of all the determinations of the thing, the existence of it has nothing to do with all this, but only with thew question whether such a thing is given, so that the perception of it can in every case precede the conception. For the fact that the conception of it precedes the perception, merely indicates the possibility of its existence; it is perception which presents matter to the conception, that is the sole criterion of reality. Prior to the perception of the thing, however, and therefore comparatively a priori, we are able to cognize its existence, provided it stands in connection with some perceptions according to the principles of the empirical conjunction of these, that is, in conformity with the a.n.a.logies of perception. For, in this case, the existence of the supposed thing is connected with our perception in a possible experience, and we are able, with the guidance of these a.n.a.logies, to reason in the series of possible perceptions from a thing which we do really perceive to the thing we do not perceive. Thus, we cognize the existence of a magnetic matter penetrating all bodies from the perception of the attraction of the steel-filings by the magnet, although the const.i.tution of our organs renders an immediate perception of this matter impossible for us. For, according to the laws of sensibility and the connected context of our perceptions, we should in an experience come also on an immediate empirical intuition of this matter, if our senses were more acute--but this obtuseness has no influence upon and cannot alter the form of possible experience in general. Our knowledge of the existence of things reaches as far as our perceptions, and what may be inferred from them according to empirical laws, extend. If we do not set out from experience, or do not proceed according to the laws of the empirical connection of phenomena, our pretensions to discover the existence of a thing which we do not immediately perceive are vain. Idealism, however, brings forward powerful objections to these rules for proving existence mediately. This is, therefore, the proper place for its refutation.
REFUTATION OF IDEALISM.
Idealism--I mean material idealism--is the theory which declares the existence of objects in s.p.a.ce without us to be either () doubtful and indemonstrable, or (2) false and impossible. The first is the problematical idealism of Descartes, who admits the undoubted certainty of only one empirical a.s.sertion (a.s.sertio), to wit, "I am." The second is the dogmatical idealism of Berkeley, who maintains that s.p.a.ce, together with all the objects of which it is the inseparable condition, is a thing which is in itself impossible, and that consequently the objects in s.p.a.ce are mere products of the imagination. The dogmatical theory of idealism is unavoidable, if we regard s.p.a.ce as a property of things in themselves; for in that case it is, with all to which it serves as condition, a nonent.i.ty. But the foundation for this kind of idealism we have already destroyed in the transcendental aesthetic.
Problematical idealism, which makes no such a.s.sertion, but only alleges our incapacity to prove the existence of anything besides ourselves by means of immediate experience, is a theory rational and evidencing a thorough and philosophical mode of thinking, for it observes the rule not to form a decisive judgement before sufficient proof be shown. The desired proof must therefore demonstrate that we have experience of external things, and not mere fancies. For this purpose, we must prove, that our internal and, to Descartes, indubitable experience is itself possible only under the previous a.s.sumption of external experience.
THEOREM.
The simple but empirically determined consciousness of my own existence proves the existence of external objects in s.p.a.ce.
PROOF
I am conscious of my own existence as determined in time. All determination in regard to time presupposes the existence of something permanent in perception. But this permanent something cannot be something in me, for the very reason that my existence in time is itself determined by this permanent something. It follows that the perception of this permanent existence is possible only through a thing without me and not through the mere representation of a thing without me.
Consequently, the determination of my existence in time is possible only through the existence of real things external to me. Now, consciousness in time is necessarily connected with the consciousness of the possibility of this determination in time. Hence it follows that consciousness in time is necessarily connected also with the existence of things without me, inasmuch as the existence of these things is the condition of determination in time. That is to say, the consciousness of my own existence is at the same time an immediate consciousness of the existence of other things without me.
Remark I. The reader will observe, that in the foregoing proof the game which idealism plays is retorted upon itself, and with more justice.
It a.s.sumed that the only immediate experience is internal and that from this we can only infer the existence of external things. But, as always happens, when we reason from given effects to determined causes, idealism has reasoned with too much haste and uncertainty, for it is quite possible that the cause of our representations may lie in ourselves, and that we ascribe it falsely to external things. But our proof shows that external experience is properly immediate,* that only by virtue of it--not, indeed, the consciousness of our own existence, but certainly the determination of our existence in time, that is, internal experience--is possible. It is true, that the representation "I am," which is the expression of the consciousness which can accompany all my thoughts, is that which immediately includes the existence of a subject. But in this representation we cannot find any knowledge of the subject, and therefore also no empirical knowledge, that is, experience.
For experience contains, in addition to the thought of something existing, intuition, and in this case it must be internal intuition, that is, time, in relation to which the subject must be determined.
But the existence of external things is absolutely requisite for this purpose, so that it follows that internal experience is itself possible only mediately and through external experience.