Leibniz's New Essays Concerning the Human Understanding · John Dewey
THE NATURE AND EXTENT OF KNOWLEDGE.
But being tied to the view that reality is distinct from intelligence, it is obliged to draw the conclusion that these relations are not to be found in actual existence, and hence that all knowledge, whatever else it may be, is unreal in the sense that it does not and cannot conform to actual fact. But, in the theory of Leibniz, the process of relating which is the essence of knowledge is only the realization on the part of the individual mind of the relations or reasons that eternally constitute reality. Since reality is, and is what it is, through intelligence, whatever relations intelligence rightly perceives are not "extraneous" to reality, but are its "essence." As Leibniz says, "Truth consists in the relations between the objects of our ideas. This does not depend upon language, but is common to us with God, so that when God manifests a truth to us, _we acquire what is already in his understanding_. For although there is an infinite difference between his ideas and ours as to their perfection and extent, yet it is always true that as to the same relation they are identical. And it is in this relation that truth exists." To this may be added another statement, which throws still further light on this point: "Ideas are eternally in God, and are in us before we perceive them."
We have now to consider somewhat more in detail the means by which the transformation of empirical into rational knowledge is carried on. Leibniz points out that the difficulty concerning scientific knowledge of sensible facts is not lack of data, but, in a certain sense, superfluity of data. It is not that we perceive no connections among objects, but that we perceive many which we cannot reduce to one another. "Our experiences," says Leibniz, "are simple only in appearance, for they are always accompanied by circumstances connected with them, although these relations are not understood by us. These circumstances furnish material capable of explanation and analysis. There is thus a sort of _pleonasm_ in our perceptions of sensible objects and qualities, since we have more than one idea of the same object. Gold can be nominally defined in many ways. Such definitions are only _provisional_." This is to say, empirical knowledge will become rational when it is possible to view any subject-matter as a unity, instead of a multiplicity of varied aspects. And on this same subject he says, in another connection: "A great number of experiences can furnish us data more than sufficient for scientific knowledge, provided only we have the art of using these data." The aim of science is therefore, to discover the dynamic unity which makes a whole of what appears to be a mere mass of accidentally connected circumstances. This unity of relations is the individual.
It is thus evident that to Leibniz the individual is not the beginning of knowledge, but its goal. The individual is the organic, the dynamic unity of the variety of phases or notions presented us in sense-experience. Individuality is not "simplicity" in the sense of Locke; that is, separation from all relations. It is complete connection of all relations. "It is impossible for us to have [complete] knowledge of individuals, and to find the means of determining exactly the individuality of anything; for in individuality all circumstances are combined. Individuality envelops the infinite. Only so far as we know the infinite do we know the individual, on account of the influence (if this word be correctly understood) that all things in the universe exercise upon one another." Leibniz, in short, remains true to his conception of the monad as the ultimate reality; for the monad, though an individual, yet has the universe as its content. We shall be able, therefore, to render our sensible experiences rational just in the degree in which we can discover the underlying relations and dependencies which make them members of one individual.
For the process of transformation Leibniz relies especially upon two methods,--those of mathematics and of classification. Of the former he here says but little; but the entire progress of physical science since the time of Leibniz has been the justification of that little. In the passage already quoted regarding the need of method for using our sensible data, he goes on to say that the "infinitesimal analysis has given us the means of allying physics and geometry, and that dynamics has furnished us with the key to the general laws of nature." It is certainly competent testimony to the truth of Leibniz's fundamental principles that he foresaw also the course which the development of biological science would take. No classification based upon resemblances, says Leibniz in effect, can be regarded as wholly arbitrary, since resemblances are found in nature also. The only question is whether our classification is based upon superficial or fundamental identities; the superficial resemblances being such as are external, or the effects of some common cause, while the fundamental resemblances are such as are the cause of whatever other similarities are found. "It can be said that whatever we compare or distinguish with truth, nature differentiates, or makes agree, also; but that nature has differences and identities which are better than ours, which we do not know. . . . _The more we discover the generation of species_, and the more we follow in our classifications the conditions that are required for their production, the nearer we approach the natural order." Our classifications, then, so far as they depend upon what is conditioned, are imperfect and provisional, although they cannot be said to be false (since "while nature may give us those more complete and convenient, it will not give the lie to those we have already"); while so far as they rest upon what is causal and conditioning, they are true, general, and necessary. In thus insisting that classification should be genetic, Leibniz anticipated the great service which the theory of evolution has done for biological science in enabling science to form classes which are "natural;" that is, based on identity of origin.
Leibniz culminates his discussion of classification as a method of translating the empirical into the rational, by pointing out that it rests upon the law of continuity; and that this law contains two factors,--one equivalent to the axiom of the Realists, that nature is nowhere empty; the other, to that of the Nominalists, that nature does nothing uselessly. "One of these principles seems to make nature a prodigal, the other a miser; and yet both are true if properly understood," says Leibniz. "Nature is like a good manager, sparing where it is necessary, in order to be magnificent. It is magnificent in its effects, and economical in the causes used to produce them." In other words, classification becomes science when it presents us with both unity and difference. The principle of unity is that of nature as a miser and economical; that of differentiation is the principle of nature as prodigal and magnificent. The thoroughly differentiated unity is nature as self-specifying, or as an organic, not an abstract, unity. The gist of the whole matter is, then, that experience presents us with an infinity of ideas, which may appear at first sight arbitrary and accidental in their connections. This appearance, however, is not the fact. These ideas are the effects of certain causes; and in ascertaining these conditions, we reduce the apparently unrelated variety of experiences to underlying unities, and these unities, like all real unities or simple beings, are spiritual and rational in nature. Leibniz's ordinary way of stating this is that the principle of truths of fact is that of _sufficient reason_. This principle Leibniz always treats as distinguished from that of identity (and contradiction) as the ruling category of truths of reason. And we shall follow him in discussing the two together.
"Our reasonings are based on two leading principles,--that of contradiction, in virtue of which we judge false all which contains contradiction, and true that which is opposed or contradictory to that which is false; and that of sufficient reason, in virtue of which we judge that no fact is true or actual, no proposition veritable, unless there is a sufficient reason why it is as it is, and not otherwise, although these reasons are generally unknown to us. Thus there are two sorts of truths,--those of reason, and those of fact. The truths of reason are necessary, and their opposites impossible; while those of fact are contingent, and their opposites possible. When a truth is necessary, its reason can be discovered by analysis, resolving it into ideas and truths that are simpler, until the primitive truths are arrived at. It is thus that the mathematicians proceed in reducing by analysis the theorems of speculation and the canons of practice into definitions, axioms, and postulates. Thus they come to simple ideas whose definition cannot be given; primitive truths that cannot be proved, and which do not need it, since they are identical propositions, whose opposite contains a manifest contradiction."
"But in contingent truths--those of fact--the sufficient reason must be found; namely, in the succession of things which fill the created universe,--for otherwise the analysis into particular reasons would go into detail without limit, by reason of the immense variety of natural things, and of the infinite divisibility of bodies. There are an infinity of figures and of past and present movements which enter into the efficient cause of my present writing, and there are an infinity of minute inclinations and dispositions of my soul which enter into its final cause. And since all this detail contains only other contingent and particular antecedents, each of which has need of a similar analysis to account for it, we really make no progress by this analysis; and it is necessary that the final or sufficient reason be outside the endless succession or series of contingent particulars, that it consist in a necessary being, in which this series of changes is contained only _eminenter_, as in its source. This necessary being and source is what we call God."
In other words, the tracing of empirical facts to their causes and conditions does not, after all, render them wholly rational. The series of causes is endless. Every condition is in turn conditioned. We are not so much solving the problem of the reason of a given fact, as we are stating the problem in other terms as we go on in this series. Every solution offers itself again as a problem, and this endlessly. If these truths of fact, then, are to be rendered wholly rational, it must be in something which lies outside of the series considered as a series; that is, something which is not an antecedent of any one of the series, but is equally related to each and to all as their ground and source. This, considered as an argument for the existence of God, we shall deal with hereafter; now we are concerned only with its bearing upon the relation of experience to the universality and necessity of knowledge. According to this, the ultimate meaning of facts is found in their relation to the divine intelligence; for Leibniz is emphatic in insisting that the relation of God to experience is not one of bare will to creatures produced by this will (as Descartes had supposed), but of a will governed wholly by Intelligence. As Leibniz states it in another connection, not only matters of fact, but mathematical truths, have the same final basis in the divine understanding.
"Such truths, strictly speaking, are only conditional, and say that in case their subject existed they would be found such and such. But if it is again asked in what consists this conditional connection in which there is necessary reality, the reply is that it is in the relation of ideas. And by the further question, Where would be the ideas if no spirit existed; and what would then become of the foundation of the certainty of such truths?--we are brought to the final foundation of truths; namely, that supreme and universal spirit, which must exist, and whose understanding is, in reality, the region of the eternal truths. And in order that it may not be thought that it is not necessary to have recourse to this region, we must consider that these necessary truths contain the determining reason and regulative principle of existence, and, in a word, of the laws of the universe. Thus these necessary truths, being anterior to the existences of contingent beings, must in turn be based upon the existence of a necessary substance." It is because facts are not _mere_ facts, in short, but are the manifestation of a "determining reason and regulative principle" which finds its home in universal intelligence, that knowledge of them can become necessary and general.
The general nature of truths of reason and of their ruling principle, identity and contradiction, has already been given in the quotation regarding the principle of sufficient reason. It is Leibniz's contention that only in truths whose opposite is seen to involve self-contradiction can we have absolute certainty, and that it is through connection with such eternal truths that the certainty of our other knowledge rests. It is thus evident why Leibniz insists, as against Locke, upon the great importance of axioms and maxims. They are important, not merely in themselves, but as the sole and indispensable bases of scientific truth regarding all matters. Leibniz at times, it is true, speaks as if demonstrative and contingent truths were of themselves, in principle, distinct, and even opposed. But he also corrects himself by showing that contingency is rather a subjective limitation than an objective quality. We, indeed, do not see that the truth "I exist," for example, is necessary, because we cannot see how its opposite involves contradiction. But "God sees how the two terms 'I' and 'exist' are connected; that is, _why_ I exist." So far as we can see facts, then, from the standpoint of the divine intelligence, so far, it would appear, our knowledge is necessary.
Since these axioms, maxims, or first truths are "innate," we are in a condition to complete (for the first time) the discussion of innate ideas. These ideas constitute, as we have learned, the essential content of the divine intelligence, and of ours so far as we have realized our identity with God's understanding. The highest form of knowledge, therefore, is self-consciousness. This bears the same relation to necessary truths that the latter bear to experience. "Knowledge of necessary and eternal truths," says Leibniz, "distinguishes us from simple animals, and makes us have reason and science, _elevating us to the knowledge of ourselves_. We are thus developed to self-consciousness; and in being conscious of ourselves we are conscious of being, of substance, of the simple, of the spiritual, of God." And again he says that "those that know necessary truths are rational spirits, capable of self-consciousness, of recognizing what is termed Ego, substance, and monad. _Thus_ they are rendered capable of demonstrative knowledge." "We are innate to ourselves; and since we are beings, being is innate to us, for knowledge of it is implicit in that which we have of ourselves."
Knowledge, in fine, may be regarded as an ascending series of four terms. The first is constituted by sensations associated together in such a way that a relation of antecedence and consequence exists between them. This is "experience." The second stage comes into existence when we connect these experiences, not by mere relations of "consecution," but by their conditions, by the principle of causality, and especially by that of sufficient reason, which connects them with the supreme intelligence, God. This stage is science. The third is knowledge of the axioms and necessary truths in and of themselves, not merely as involved in science. The fourth is self-consciousness, the knowledge of intelligence, in its intimate and universal nature, by which we know God, the mind, and all real substance. In the order of time the stage of experience is first, and that of self-consciousness last. But in the lowest stage there are involved the others. The progress of knowledge consists in the development or unfolding of this implicit content, till intelligence, spirit, activity, is clearly revealed as the source and condition of all.
Ideas discussed in this chapter
Text from Project Gutenberg, public domain in the United States.