A history of the principle of sufficient reason: its metaphysical and logical formulations ...

CHAPTER I. Introductory. — The Problem

The following essay may be looked upon as an attempt to show, by means of a historical study of the development of the principle of Sufficient Reason, the standpoint occupied by the modern German logicians, as contrasted with the Epistemologists of the metaphysical schools. As the title indicates, the nature of the principle has completely changed in the development of post-Leibnitzian thought. In its origin, conceived of as extra-logical, as metaphysical and as identified with the causal axiom, it has finally been accorded the place of basal law of the logical consciousness and only secondarily connected with the real relations of causality.

The extension of the bounds of the logical consciousness, involved in this transformation, the critical determination of the relation of metaphysical to logical principles resulting from such a development are both phenomena characteristic of the modern " Erkentniss-theoretische " logic.

It is the writer's notion that the achievement of these characteristic standpoints is in great part the result of reflection'upon the nature of this Law of Ground, variously formulated as metaphysical and logical, and that a conscientious study of the history of the principle would throw much light upon the growth of our broader view of logic.

In addition to this the writer was much charmed with theelements of clearness and unity which Schopenhauer, despite his many metaphysical sins, was enabled to give to his thinking by following the guiding thread of the specific yet far-reaching problem of Sufficient Reason. And what istrue of Schopenhauer in so great a degree, may be said with more or less truth of all the great philosophers since Leibnitz. How should we have so clear a notion of Kant's chapter upon the " Grundsatze der reinen Verstandes begriffe " if he had not gathered them all under the one principle of ground ? Without Herbart's " Methodologie," which has the problem of ground and consequence as the main object of his dialectical interest, the rest of the " Metaphysik ' r were scarcely understandable.

. The conncxio rcrum is the great problem of metaphysics, the connexio idearum the last question of logic in its broadest sense, and in no way have the mutual relations of the two been so subtly elucidated as in the critical study of this basal principle of Sufficient Reason.

Starting then with these two ideas, on the one hand, if possible, of showing the fundamental place of the principle under consideration, in the philosophical systems of the more important Post-Leibnitzians, and secondly of discovering, in the development of the law likewise the development of the modern concept of logic and its problems, my study has produced the following essay.

A short preliminary chapter upon the Pre-Leibnitzians, attempts to show the conditions out ot which Leibnitz's quite original formulation of this entirely new principle arose. Leibnitz is treated with considerable detail with the desire of showing that his formulation discloses the presence of two motives, one which tended to formulate the law as a Logical principle, the other, the one which finally predominated being metaphysical, reduced the problems of the grounds of knowledge to a metaphysical determinism.

The succeeding history of the principle is then conceived

Khibit three main stag( i. The metaphysical formulation of Sufficient Reason, from Leibnitz through Kant and Schopenhauer.

2. A struggle between metaphysical and logical attitudes iu Herbart and Trendelenburg.

3. The logical formulation in the modern logicians, Sigwart, Wundt, &c.

Two questions which may arise, why, on the one hand, the study is limited to German thinkers, and secondly, why Fichte, Schelling and Hegel are omitted, are answered simply :

By the consideration of the fact that the problem, as limited by our study, is exclusively German, the only extra German thinker who has handled the technical problem of Sufficient Reason being the Kantian, Sir Wm. Hamilton; and secondly, the immediate Post-Kantians, especially Hegel, represent no new phase of the problem, but rather a return to the conditions against which Leibnitz's formulation arose as a protest, the pre-critical, pan-logism of the Spinozistic type.

The following study is then concerned with the interplay of these two distinct motives, the logical and the metaphysical, or rather perhaps with the two ways of defining the principle of Sufficient Reason. This is the basal law of all knowledge, this Law of Ground, and according as it is conceived as extra-logical and metaphysical, or on the other hand as the most general law of logic, is our whole theory of knowledge affected.

The argument of the succeeding historical study is briefly that the origination and first formulation of the principle in Leibnitz's thinking, represents a stage of inconsistency in which both motives, both attitudes stand in more or less contradiction, and that the succeeding movement at first manifests a decided trend toward the metaphysical side, to be re-placed in more modern thought by the reformation of the logical point of view, broadened and changed.

I. Leibnitz's origination of the principle of Sufficient Reason is found to have arisen out of a protest against the general trend o-f previous thinking toward a reduction of empirical causal relations to logical grounding, as typified in the pan-logism of Spinoza. 1 Asa consequence S. R. is conceived as purely empirical and extra-logicaL 2 Since its validity is not grounded in general logical considerations, Leibnitz seeks to ground it in his peculiar metaphysical: system the Monadologie. The metaphysical causality of the monadic development being the ground of empirical happening, Sufficient Reason is identified with the Causal Axiom, thus rescuing the Causal Axiom from a purely logical treatment, but setting the current in the direction of a metaphysical formulation of the new principle. 3 The logical consequence of this identification of causation with S. R., that S. R. be conceived as a principle of determination, just as the logical norms, Leibnitz did not admit, but insisted that this law was only one of sufficient reason instead of determining ground. 4 At this point Crusius takes up the problem substituting " determinateness " for "sufficiency" and distinguishing besides the ideal grounds, two distinct kinds of real metaphysical grounding, the grounds of will acts and the causes of empirical happening. The problem of "determinism," in the moral sphere, thus forces the metaphysical side of the problem into the foreground. 5

The advent of the critical philosophy of Kant, represents, strange as it may seem, on one side at least, a further development of this metaphysical treatment of S. R. He maintains the idea of Crusius that the law of ground is a principle of determination and not of " sufficiency," and accepts the "determination" element in the judgment of ground and consequence as a necessity to be metaphysically grounded. 6 For the knowledge of this determining ground out side of logic a transcendental principle of knowledge other than Logical is then necessary. 7 Though denying the po isibilif v oi an ontology of the real, he proceeds to ontologize this most fundamental of knowledge principles. It is conceived of as extra-logical and ^r^-scendental. 1 Finally Schopenhauer defines it as meta-logical and as the transcendental knot of the Subject-Object relation, which likewise marks its most complete divorce from a logical point of view, since an Intellectual Intuition of metaphysical relations is substituted for the logical thinking of ground and consequence. 2

II. What we have been led to call the logical motive for Leibnitz's formulation of the new law of knowledge, is expressed in this great thinker's attempt to formulate its place in relation to logical laws. As we have seen, it was defined as extra-logical, in view of the formal and yet metaphysical theory of logical necessity against which the new law arose as a protest. 3 And yet this very protest indicated a desire to extend the narrow bounds of the logical consciousness beyond its formal limits, so as to include all knowledge processes. Leibnitz's most general definition of S. R. is at the same time the most general definition of the logical consciousness as conceived to-day. 4 And besides logical necessity among ideas clear and distinct was conceived to be the teleological goal of the confused ideas of which S. R. was developed as the empirical law. This inherent possibilitv in the Leibnitzian thinking of extending the concepts of logic in such a manner as to include Sufficient Reason as a basal principle we shall call the logical motive.

In the Leibnitzian school itself Wolff showed a tendency, in contrast to that of Crusius, to include Sufficient Reason as a distinct logical principle, side by side with Identity and Contradiction. But his attempt to deduce S. R. from the other two laws led back to the formalism and ontological way of looking at things against which Leibnitz had protested. 5 The critical philosophy of Kant, notwithstanding the fact that on one side it is but a continuation of the metaphysical tradition, nevertheless represents a stage in the development of the modern logical consciousness, and the corresponding treatment of S. R. as the basal law of that consciousness. 1 Although S. R. is still identified with the causal axiom, it is with the causal axiom as a knowledge principle, rather than an ontological principle that Kant is concerned. In fact the Law of Ground is found only by a deduction from the logical categories 2 (causation being derived from the hypothetical judgment.) It is because of this critical balance of Kant, which sees that S. R. is essentially a relation of logical ground and consequence, although it is transcendental; in other words, because Kant remains within his transcendental logic, that Schopenhauer finds fault, and it is for this that he substitutes the doctrine of Intellectual Intuition. 3

From Herbart on, the logical motive makes itself strongly felt. The idea of Sufficient Reason as having for its goal a contradictionless whole of experience and thought, 4 gives it the place of a universal logical principle to which the formal laws of Identity and Contradiction are subordinated, although Herbart is not able to formulate the law without a metaphysical basis. But already in his concept of the "widened ground," which should include the whole nexus out of which the consequence springs lies the germ of a broader view ot logic/' Sufficient Reason, the most general term for all necessary relations in knowledge, has as its main problem the extent of its application to the real, therefore its relation to causality, but it is not identified with causation. ,;

Through the intermediate stages of Trendelenburg and Drobisch, to the former of whom, the concept of logic included the entire phenomenology of the judgment, formal and material; 7 while the latter, i hough retaining the concept of a purely formal logic, formulates Sufficienl Reason as the basal law ol logic/ the modern logic, as represented by

1 « ' ■ \ 1 1 5 £ 67.

Wundt, with its recognition of S. R. as basal principle, is finally reached. Sufficient Reason is here the general law of the interdependence of all acts of thought, to which the normative laws of Identity and Contradiction are subordinated. 1 And the question of its relation to causality is now a critical one — that of the relation of the causal axiom to the general logical postulate of Grounding. Sigwart, Lotze and Wundt show the impossibility of the identification of causation and Sufficient Reason, distinguishing between the determining ground as logical and the empirical complex or cause on the other hand as only sufficient. 2

The rise of this broader view of logic on account of which ^Sufficient Reason was again conceived of as purely a principle of knowledge — and not a metaphysical law of the real to be identified with causality was much aided by a new motive which entered into German thought with the advent of the Kantian " Kritik." This may be characterized as an attempt to get at the phenomenology of the grounding process. Thus, in addition to the " Objective Deduction" of the concepts of the Understanding, substance and causality, from the logical categories, a "subjective" deduction is added which shall show how, from the nature of our mental processes, such objective judgments are possible. 3 It is, as Kant himself says, something of the nature of an hypothesis of causes for the given results in judgment. He has in mind an immanental Sufficient Reason or logical causality working in the processes themselves. 4 This immanental logical -causality includes psychological material elements, and thus is paved the way for a study of the phenomenology of the logical processes and for a broader view of the logical consciousness. This genetic point of view was already suggested by the Leibnitzian theory of a 'teleological movement of consciousness from the obscure, >confused ideas, that is from psychological sufficiency to the ^necessity of the logical clearness and distinctness of the eternal ideas, but could not come to complete expression r . owing to the metaphysical interpretations put upon it by the Monadologie. Herbart, who represents a stage of conflict between the metaphysical and logical formulations of S. R., in his conception of the logical ground so widened as to include elements not in the conception as amenable to formal logic, conceives this widening as brought about by chance suggestions, by " Zufalligen Ansichten," thus admitting a psychological element into the process of grounding. 1 Although the logical causality thus suggested is reduced in his system to metaphysical terms, yet it is important to recognize that Sufficient Reason as a principle of knowledge is conceived to be an immanental necessity broader than the necessity of formal logic.

Trendelenburg's theory that logic should be extended to include the material, psychological as well as the formal elements in the judgment, brings the problem of phenomenology to the front. The modal categories of thought, possibility, reality, and necessity are, after the manner of Kant's " subjective deduction," conceived as phenomenological moments in the grounding process, in which the formal and material elements are united. 2 It is especially Trendelenburg, who, against the psychological doctrine of " Zufall" in the grounding processes develops his doctrine of the teleological nature of all grounding processes. 3 They are a- " wahres Geschehen " under the law of teleological causality, the goal of which causality is Knowledge, including Thought and Being. The postulate of an immanental logic, functioning in all judgment processes, becomes a permanent element in modern Logic, in Sigwart and Erdman. 4 In Wundt, finally, the concept of a Logical Causality as the Law ol Ground in its primary form, governing the higher apperceptive proi I- set over against the empirical applications

of this law, the Causal Axiom, in its two expressions physical and psychological causality. The teleological necessity.

of our thought processes is the Law of Ground seen inwardly. 1

In conclusion, we may make our object and method clearer by comparing- in a general way the present problem with that which Konig sets himself to solve in his extensive history of the "Causal Problem." 2 Here, by an exhaustive study, covering two volumes, and comprising a detailed exposition and criticism, the author seeks to secure valid results for the causal concept of to-day. This involves not only the complete metaphysics, but explains the psychological and natural science standpoints of the authors under consideration. The present essay, on the contrary, aims only to show that there has been a continuity in reflection upon this more general and more formal principle of Sufficient Reason ; that, in the changes of attitude toward it, now constructing it logically and again metaphysically, and secondly in the way in which natural and psychological causality have been conceived to be related to it, an instructive insight, not blurred by too much data, may be afforded into that somewhat difficult province, the border-land between Metaphysics and Logic. In view of this limitation of the problem, the writer may then hope to be pardoned for what may appear from another standpoint an insufficient treatment of very deep and thorough thinkers.

* CHAPTER II.

Pre-Leibnitzian Thought.

§ i. In order to understand the origin of Sufficient Reason as a general unifying term, under which the more particular problems of the Science of Knowledge might be put forward, as well as to secure an insight into the reasons for its dominance of German thought from Leibnitz to the present day, it is necessary to sketch the general tendencies of pre^ Leibnitzian thought.

'* Konig, Edward, " Die Entwickelung des Causal-Problems,'" Leipzig, 1888.

IO

There are discoverable tendencies toward a unification of the problems of knowledge, which, though general, are yet so evident as to excuse the anachronism, of referring for the sake of conciseness, to expressions of Sufficient Reason before its actual formulation in Leibnitz.

Provisionally, then, it may be said that Greek thinking tended to formulate Sufficient Reason in terms of a naive real logic of experience. Christian thought, as typified in Augustinre, sought it in an introspective determination of the conditions of Belief. The Reason of the former was the certainty of the external Intuition, corrected by a dialectical removal of contradictions; that of the latter the satisfaction and certainty of the subjective intuition of the self.

These general norms being once attained, the tendency was to give them universal validity. Thus, Aristotle is found studying the movements of knowledge and of ps}' , chological processes in general under the same categories as external happening. Augustine, on the contrary, can understand historical happening only as the expression of the Divine Will, constructed on the analogy of the experiences of his own subjective willing self and its necessities.

§ 2. The Greek formulation of Sufficient Reason reached its fullest expression in Aristotle, — his doctrine of causation, Lotze calls the first formulation of the Law of Ground. But from this doctrine of causation should not be separated Aristotle's applied logic and the realistic doctrine of concepts which it involves. The two are closely bound together and their unity alone affords the basis for a unitary formulation. The distinction between formal and applied Logic, in the modern sense, according to which, as shall appear later. Sufficient Reason is defined as logical, its application- being material, was not yet made. The real concept, as participating in the idea, lends itself equally well to logical forms and causal constructions— on its ideal side to

logical formal relations, on its real side to causal construction. To formulate a general law, therefore, the whole

sphere ot mediate knowledge, lying between the intuition ol perception, "which is for us first" and the intuition of the ideas, "which is in itself first" to use Aristotle's terms, all lying between these two extremes of the immediately certain, requires sufficient grounds for its certainty. 1 These grounds may be determined either by the laws of logic, as developed by Aristotle, or by his fourfold doctrine of causation. The important point is that in either case the concepts dealt with are real, as well as rational, and the conclusions either of the principles of logic or of the laws of causation are unquestioned constructions of the real. No deep-rooted distinction is made between the logical and the causal side of thought, because the deeper distinctions of the subjective and objective had not arisen. The lack of this distinction between formal logical thought and concrete real thought is characteristic of a unitary metaphysical point of view. It is the naive rationalism which, though it may distinguish between ideal and real grounds, makes no essential break between them.

§ 3. From the very beginning of Greek thought this naively rationalistic attitude toward reality was marked. All attempts to solve the problems of Being and, especially, of Becoming, which arose to challenge this attitude, were characterized by the use of concepts which contained already the presupposition of their reality. The vote of Anaxagoras, the logical principles of Zeno, Identity and Contradiction, the number system of the Pythagoreans were not handled as principles of knowledge but as directly analysed out of reality. And when Plato became convinced of the dualism between the material and ideal world, the essential rationalism of Greek thought prevented him from taking the step which would to modern thought necessarily follow, of distinguishing between real cause and ideal ground. The ideas are made the causes of material things and are called causes, 2 and even force is ascribed to them by means of which they are able to work upon us and make themselves known. 3

8 In the Phaedrus, where Plato's doctrine of Ideas first appears, it is confined to anoral ideas.

This brings with it a complete confusion of ideal and real grounds. 1 The ideas are both causes and grounds for the knowledge of the real of perception, of which, without the mediation of the ideas, there is no knowledge but only belief. 2

For the knowledge of this world of appearance the ideas must be taken into service. But they in turn can only be known in an intuition out of time.

§4. In Aristotle there is no material change in the general conception of the essential sameness of logical ground and real cause. As we have seen, the validity of the causal and logical laws alike rests upon the reality of the general con-' cept. Thus Schopenhauer has gathered together in his historical sketch numerous quotations in which a logical premise is called cause, aircov being used for every sort of ground. 3 Logical thoughts as well as psychological phenomena are looked upon as a real happening subject to the same construction as other external movements. One difference may be distinguished however. The ideas as pure form, in Plato's sense, are no longer looked upon as causes either of perception or of natural phenomena, but Aristotle has reached a critical standpoint from which he is able to see that only the general concept, as containing ideal and real elements in union, may be conceived of causally. 4 Thus instead of Plato's simple ideal causation arises Aristotle's more complex doctrine of a fourfold causation, of which moving and end causes are the more important. The idea is cause only in so far as it is natural force and teleological end. But although both moving and end cause, are considered principles of Sufficient Reason of Becoming, the stress is put upon the teleological side. The cause is poten-

1 This confusion is characteristic of a stage where the postulate of ground is not

yet recognized, formulated as a basal principle of thought, but only acts unconscious of

itself. So all the formulations of Plato appear to us, as Schopenhauer says — " wie der

Stand der (Jnschuld gegen den der Erkentniss des Guten und BOsen." Vierfache

'.-]>. [9— cf. also Philebui p. 240.

pluies — Psychologic dei Erkennens % Leipzig, [893. Anhang % Par. 7. • " Vierfache Ww Zureichenden Grundes" £ 56.

tentiallty of the effect, because the idea of the effect is considered to be already in the cause. In order, therefore, that a present real might be seen to be the outcome of preceding real conditions, into these conditions was read an ndea which rationally could be seen to be the dunamis of the ; present state. 1

§5. If for the sake of clearness we follow the use of a -biological analogy, we may call attention to the extremely undifferentiated state of this life-principle of thought — this .fundamental motive of Sufficient Reason. In the absence of a sense of the difference even between the necessities of thought and reality, it is still less to be expected that we shall find a strong sense of the difference between the necessities in different spheres of reality — or between subjective sufficiency and objective necessity. In fact, these differentiations, in thought as in material development, appear only as the result of tedious processes. To the first of these differentiations, the source of the distinction between subjective and objective necessity, our attention must now be turned.

§ 6. In addition to the naive rationalism of Greek thinking, a second ingredient found its way into modern philosophy, a force which, though less obtrusive, is perhaps equally to be reckoned with — namely, the subjective psychological doctrine of belief of Mediaeval thought, as formulated in Augustine. This, as has already been suggested, sought the grounds of real judgments in an introspective determination of the subjective conditions of belief. And the norm, according to which external realities are judged, is the certainty of the subjective intuition of the self. Belief, which according to Plato and Aristotle lay outside the sphere of knowledge, 2 becomes the very presupposition of knowledge. Credo ut intelligam is by no means merely a theological axiom, but locates the problem of the grounds of

1 Ueberweg und Heinze, Geschichte der Philosophies 7th Edition, Vol. I, page 203. Aristotle Anal. Post, 87, b, 31. 2 Cf. § 3.

H

knowledge in the subjective assent which accompanies all judgment. 1

§7. This subjective assent or belief, which is evidently in the first place psychological, is, however, conceived by Augustine to be grounded. It is with the nature of this grounded sufficiency that we are alone concerned. That something appears in consciousness is certain. Our doubt can only extend to the nature of that something. 2

Now, that which is given to us most certainly and really is the consciousness of self, not as a metaphysical substance, but as a willing, believing, doubting self — even the last element of doubt making the certainty of the self presence more absolute, as Descartes likewise argued. The self is the source of all assent — and the certainty of the self the norm of the certainty in our assent to other realities. 3 Thus he argues; reality must be discovered within us to be afterward extended to the external world — for that to which we give our subjective assent of the will is, as Augustine with insight expresses it, ''our life." "That which later ripens into knowledge must first be grasped by faith; w T ho disdains faith will never be able to raise himself to knowledge." 4 Self-certainty is then the norm according to which assent is given to the reality of the elements that enter consciousness.

£ 8. But the important question arises how may this subjective certainty, arising out of the assent of the will, which Augustine believes to be prior to our extension of knowledge to the external world, be conceived to be valid also for external reality. At this point the Will Metaphysics of Augustine enters, together with his Theism. The Will of God, as ground of the world, made alter the pattern of the Eternal Ideas (a neoplatonic element in his system), is the source of our will, as part of the world, and therefore works

* " Contra AccuUm" [II, C, 11.

i5

upon the finite will, determining our subjective assent or disbelief. Thus is our belief in the truths of the external world a direct function of our subjective assent. And for Augustine there is really no causality except that deducible, theologically, from the nature of the Will of God, and noknowledge except that vouchsafed to our subjective belief.

§ 9. The reason for our treatment of the Augustinian doctrine of assent, is that it is a typical expression of an important element of subjective grounding, taken up into later philosophy, especially the Cartesian. It expresses, too, the exactly opposite standpoint from the Aristotelian, in that while the reality of the general concept is in the former taken for granted, here concrete subjective reality is the starting point. They are alike in this, however, that as in the former the grounds of logical knowledge and causes in reality are not distinguished, because the reality of the general concepts is the basis of both, so also in Augustine the grounds of truth as discovered in assent, just as the grounds of external reality, are in both cases ultimately to be found in the will of God.

Thus reconstructing Augustine's theory of Sufficient Reason in modern terms, it might be said that to him, whatever satisfies the demands of the Will for the real, and is taken up by the transcendental belief, without which the inner life is impossible, is true. Whatsoever can be shown to be grounded in the Will of God is real. In both cases the grounds are ultimately the same.

§ 10. This Formulation of Ratio Sufficients is, at bottom, the expression of the whole mediaeval intuition of the world. As Dilthey expresses it " Weiter als Augustinus hat kein mittelalterlicher Mensch gesehen." What followed was but an impossible attempt to graft the Aristotelian rationalism of concepts upon this Will metaphysic — but it remained always " fremdes Gut."

The Realists sought to find concepts which by their very definition would include their reality, concepts which thus by the mere application of the Aristotelian syllogism, i6

would build a whole system of objective truth; but these verv concepts of the religious consciousness were in reality but products of the religious belief that Augustine had grounded, and were capable of no more scientific proof. This tendency reached its culmination in the famous Anselmian proof of the existence of God. Against this movement appeared, from time to time, the Nominalists, who by means of the weapons of scepticism, sought to retain the doctrines of belief grounded on the old Augustinian Will metaphysic. The final conflict was fought out between Duns Scotus and St. Thomas, — of whom the former was Augustinian and the latter Aristotelian. But already in the 13th century men had begun to speak of a " Two Fold Truth," for which there should be two entirely different instruments of investigation, one for theology and another for secular sciences. Thus began to arise among the scientists a mechanical doctrine of causation, which later in modern philosophy should supply the Ratio Sufficiens of Becoming, of existendi, which, as we have already seen, failed entirely in the thinking of Augustine.