Schopenhauer and the Empirical Critique of Idealism in the History of Ideas
Eisel Mazard

Introductory Note. {Or, click here to skip to the main text} I had no intention of publishing (or posting) this essay on Schopenhauer, but as I now see others (in various articles on the internet) wrestling with the same flawed secondary sources that I once struggled with, and bemoaning that there are no clear answers to be found on some very preliminary (and very fundamental) questions as to Schopenhauer's place in the history of philosophy, I have decided to make the paper available. The main advantage for the reader (in giving a few hours to this little tract) is that the essay draws together quotations from numerous diverse sources that demonstrate the main points of its argument directly from Schopenhauer's own pen.  Although the essay is not easy to read, it is indeed much easier than undertaking the huge volume of primary-source reading that it was based upon; and while it was more intended as an antidote to the secondary source material that already exists (in English), it can also serve as a kind of introduction to Schopenhauer's work for those who have not yet become familiar with (i.e., exasperated by) that small literature. Apart from mere philosophy, the text comprises:

  1. A very clear set of conclusions as to what Schopenhauer's relationship is (and is not) to the philosophies of Kant, Leibniz, Fichte, Schelling, etc., drawing on the neglected/ignored sources of Schopenhauer's own writing on these questions;

  1. Some useful indications as to the importance of certain influences from schools of thought outside of (and sometimes opposed to) the tradition of "German Idealism" in understanding the origins and meaning of Schopenhauer's philosophy;

  1. A practical explanation of Schopenhauer's own understanding of the primary importance of his philosophy in the history of European thought, being, in his terms, "A solution to the problem of the ideal and the real"; and whereas it is indeed important for criticism to diverge wildly from an author's own evaluation of any work, most of the secondary sources have undertaken this without understanding the basic premise of what Schopenhauer was (and was not) attempting to accomplish in his writing.  We thus (very frequently) find Schopenhauer reproached for failing to prove things that he was not, in fact, attempting to prove, etc.

It must finally be complained that very few English-language secondary sources on Schopenhauer (including, or perhaps especially, the work of B. Russell) demonstrate any detailed knowledge of the primary sources, or even any broad reading of the oeuvre; and I think it rather inexcusable when published authorities issue their opinions from simple ignorance of the texts they pretend to judge, especially given that Schopenhauer's work is not terribly voluminous, that it is well organized (and indexed, etc.), and readily available in English translation.  I will here note in passing that, in all cases, I have preferred the more recent translations of E.F.J. Payne, to whom a debt of gratitude is owed.

By way of an excuse for the defects of the paper, I must say this: although it may seem very lengthy, this was in fact composed merely to serve as chapter 2 of a much longer essay.  I have thus tried to parse the text and eliminate references to earlier or later portions of the original composition, but there remain some thematic concerns that reflect the "broader" thesis that belonged to the original tract as a whole, and may here seem out of place.  It is also to be noted that this was written many years ago, while I was an undergraduate student struggling with the distractions of a full course load, and thus had little time for such luxuries as correct spelling or thoughtful prose; however, it was the product of about a year and a half of very disciplined reading, and I think its basic value as the "output" of that research still remains significant --for the small number of persons who are presently working with/through Schopenhauer's philosophy.

Eisel Mazard, 2005

Schopenhauer and the Empirical Critique of Idealism in the History of Ideas

Schopenhauer's indebtedness to his antecedents in European philosophy is a subject so much confused by poor scholarship and outright lies that, were we to pause to review the errors made on the matter, we should not have enough ink left over to scribble out the truth thereafter. For the correct assessment of Schopenhauer's place "In the History of Ideas" I have had no special method, nor any rare, newly uncovered document, but rather have taken advantage of the most obvious and pertinent source on this matter, which Schopenhauer has seemingly left to us for no other purpose than precisely this: the two sections opening the Parerga and Paralipomena, being the "Sketch of a History of the Doctrine of the Ideal and the Real" and the "Fragments for the History of Philosophy". Only by flagrantly ignoring the evidence of these essays have the published authorities been able to manufacture their kaleidoscope of garbled historical interpretations, i.e., to suppose and infer the most variegated of possible influences, and to proffer their arbitrary judgments on the origins, intent, and content of Schopenhauer's philosophy as if these were the best available substitute for fact. [From the] reports [of the secondary sources] one would think the subject were as obscure to history as Solon or Lycurgus, but it's only the professors' playing Plutarch that has made the matter so indistinct -- that has kicked up the dust of a millennium worth of dead-ended controversy and confusion between the nineteenth century and our own.

The story of "German Idealism", as it is shall be familiar to anyone who has come through a typical, Western university education in philosophy, is told as a constant development from Spinoza to Hegel, the latter being presented as a great crescendo, followed by a multiplicity of admirers and dissenters whose works are considered to have shaped every subsequent movement in continental philosophy:

Spinoza ⟼ Leibniz, Wolff ⟼ Kant ⟼ Fichte, Schelling ⟼ Hegel

The importance Marxism assumed in departments of philosophy through the political events of the twentieth century has formed this habit whereby we are presently taught the philosophy of the nineteenth; but the enduring cold-war formula of reducing "German Idealism" to the above sequence concluded by "Hegel and his critics" has never really served an understanding of Marx any better than it does our present interest in Schopenhauer. Rather, this lens has warped the reading of the continental philosophers, rendering Marx as incomprehensible as it does Nietzsche and Kierkegaard -- presenting the former in isolation from the influences which were so much more pertinent to his mature work than Hegel ever was (namely, liberal political economists){1}, and the latter two, without any reference to Schopenhauer, as very strange "critics of Hegel" in that their works seem predominantly concerned with commenting on, emending, or reacting to an ethical system of another origin entirely. The basic conceit that the influences of the period may be schematized into the above sequence (followed by "Left Hegelians" and "Right Hegelians") is wrong, and ought to be forsaken as a relic of an aging generation that set up this simplified narrative only to serve as a mere prologue to Marxism and Existentialism -- the significance of both of which have since diminished on the horizon. However, the model remains so prevalent to this day, that Schopenhauer's place in the history of ideas continues to be approached with the prior assumption that he must be squeezed somewhere into the sequence of "German Idealists" and "Hegelians"; but the pieces can never be made to fit. Aiken [in The Age of Ideology] is typical of his generation, finding himself compelled to fudge the facts considerably to make Schopenhauer sit next to Fichte in this linear development from Spinoza to Hegel, ignoring Schopenhauer's refutations of each and every thinker in that sequence, while lacking any conscious motive thus to lie. The false first step, which even this error must presuppose, is a simple confusion of meanings with words: the historian first assumes that Schopenhauer is, by definition, an Idealist, and upon the common sound of this word when it is spoken in reference to Spinoza, to Hegel, or to Fichte, he then supposes that Schopenhauer's role in the established story of German Idealism must in fact render him as a cumulative part of a single development with the very thinkers his works repudiate. Schopenhauer's philosophy is thus turned against its own purpose [in Aiken's history], only because it is equally to be labeled as "Idealist" along with its worst enemies -- without anyone worrying themselves for a moment as to what Idealism is, what it means, or in what sense it must be applied differently to Kant, Hegel, and Schopenhauer. The popularization of the Marxist usage (wherein "Idealism" became, like "Reactionary", an almost meaningless polemical watchword in debates) has no doubt compounded the error: no single definition of Idealism could be granted that would satisfy the requirements of both Hegel and Schopenhauer's usage --or else it would be so broad as to be meaningless. "Idealist", where it is not meant simply as a materialist's reproach to something insufficiently Marxist, tends to be used by these historians in the same capacity as "transcendental" in reference to the period -- suggesting Kant's influence, but nothing more.{2} 

The first questions that might present themselves to us, in describing Schopenhauer's historical situation [...], therefore could be, "What exactly was Schopenhauer's relation to Kant, and in what sense and to what extent may he be called an idealist?" Conversely, if we preferred to begin with a positive rather than a negative description, we should ask "To what tradition does Schopenhauer belong?" which (as I shall demonstrate shortly) equates to the question, "In what sense and to what extent may he be called an empiricist?"

It is the skeptical and exacting empiricism of The Fourfold Root of the Principle of Sufficient Reason, and the first three books of the WWR that firsts alert the student to the radically different brand of idealism he has discovered in Schopenhauer: the hypothetical-deductive method, so foreign to the soaring metaphysical speculations and Romantic claims of his contemporaries, informs and delimits Schopenhauer's work in both form and content; and this is no less evident in his ethics than in his epistemological, or psychological, or any other part of his writing, with no special exception left over to religion, metaphysics, nor any other matter.{3} What confronts us in the WWR is a systematic idealism discovered, discussed and proven, not through myth (as in Plato) nor through theological sophisms, nor bald speculation, but with the relentless empiricism of a Hobbes, a Locke, or a Hume, and predicated upon a critique of that empirical base in the tradition of Berkeley and Kant -- which is precisely the critical tradition to which list Schopenhauer adds his own name in the historical essays of the P&P. While, as I shall discuss presently, Schopenhauer is accurately called an idealist (if we understand by that term a tradition dating back to Plato's problem of eidos and idea) he is more precisely a critical idealist, and with this distinction must be understood as diametrically opposed to the speculative idealism which earned his life-long rancor and rebuff. This is no merely academic dichotomy, nor an easily overlooked difference of philosophical method: it describes a unifying characteristic of Schopenhauer's work, upon which a political expression follows as necessarily as Hegel's statism follows upon his historicism. Just as for Hobbes one and the same empiricist method leads inexorably from a study of human nature, to a critique of scripture, to an understanding of the state, Schopenhauer's empiricism remains the constant criterion in his political philosophy as much as through every step prior to it; Schopenhauer's empiricism could no more tolerate an Hegelian political philosophy (an apotheosis of the state based on theological speculations and historical abstractions) than it could allow of a Kantian ethics, or a Leibnizian metaphysics, or any other theory based on sheer speculative construction (abstraction stacked on abstraction, affirmed with "passion over reason") lacking verification in this world (and its human condition) as it may be empirically observed:

It is a characteristic fault of the Germans to look in the clouds for that which lies at their feet. An outstanding example of this is furnished by the way in which the professors of philosophy deal with the Law of Nature. In order to explain the simple relations of human life which constitute the material and substance of this, and hence right and wrong, possession, State, criminal law, and so on, the most extravagant, abstract, and consequently the vaguest and emptiest concepts are produced, and from them first one tower of Babel and then another are built into the clouds according to the special whim of the particular professor. In this way, the clearest and simplest relations of life that directly concern us are rendered unintelligible, to the great detriment of the young men who are educated in such a school. These things are extremely simple, and of this the reader may convince himself from my discussion of them in the "Basis of Ethics", §17, and in my chief work, The World as Will and Representation, volume I, §62. But with certain words, such as right, freedom, the good, to be, (this meaningless infinitive of the copula), and others, the German becomes quite giddy, falls at once into a kind of delirium, and begins to indulge in futile, high-flown phrases. He takes the vaguest and thus the hollowest concepts and artificially strings them together. Instead of this, he should keep his eye on reality... perceive things and relations as they really are from which those concepts are abstracted and which, therefore, constitute their only true substance. [P&P, vol. ii, §120]

Schopenhauer's situation in the history of ideas is thus at the intersection of idealism and critical-empiricism, or, more specifically, his role was the solution of the fundamental problem of idealism with the critical-empiricist method; this singular event in the history of philosophy, much overlooked in the histories of both traditions (for the scholarship of "Continental Idealism" and that of "British Empiricism" have been mutually antagonistic), can not be reduced to a chapter in the familiar story of German Idealism, but rather (drawing from influences utterly unrealted to Enlightenment pantheism and the speculative idealism which followed thereupon) ought to be considered in the train of Hobbes, Locke, Hume and Berkeley (in that it is a critical-empiricist philosophy), and, in its other aspect (in so far as it addresses the ideal) as a chapter in the broader history of the problem of the ideal and the real, dating back at least to Plotinus, and to Descartes in the modern era.{4} 

So what is the problem of the ideal and the real? In what sense, by addressing it, does Schopenhauer mark himself as an idealist? What is this "problem" which relates Plato to Kant, and Kant to Schopenhauer across the ages of man? It is the problem to which the WWR as a whole is posed as the solution, but its most clear restatement is to be found in Schopenhauer's first historical study in the P&P, where it is discussed simply as a problem, and not treated in passing as related to its solution:

It is the problem concerning what in our knowledge is objective and what subjective, and hence what eventually is to be ascribed by us to things different from us and what is to be attributed to ourselves. Thus in our head images arise not arbitrarily, as it were, from within, nor do they proceed from the connection of concepts; consequently, they arise from an external cause. But such images alone are what is immediately known to us, what is given. Now what relation may they have to things which exist quite separately from and independently of us and which would somehow become the cause of those images? Are we certain that such things generally exist at all, and in this case do the images generally give us any information as to their nature? This is the problem and in consequence thereof the main endeavour of philosophers for the last two hundred years has been clearly to separate by a line of cleavage correctly drawn the ideal, in other words, what belongs to our knowledge solely and as such, from the real, that is to say, what exists independently of our knowledge, and thus to determine the relation of the two to each other. [P&P, vol. i, pg. 3]

The problem of idealism is that of understanding what is phenomenon (meaning appearance, or the representation of the mind as informed by the senses) and what is left over by this broad category (which exhausts all possible knowledge predicated on experience, on sensation) to act as the necessary basis of the phenomenon outside of our apprehension (the thing-in-itself);{5} to this the supplementary question of what is object and what subject is necessarily conjoined, but the two should not be confused as a single matter, as the latter question is addressed only to knowledge (of phenomena) and therefore neither subjective nor objective knowledge can be in any way identified with the thing-in-itself. To call a philosophy "Idealist", in the proper understanding of the term, would only be to identify it as attempting to make this distinction between the ideal and the real, and thus attempting to condition all philosophy with epistemology by qualifying knowledge as phenomenological in its basis. The obverse of this is "Realism", which, in its philosophical usage (and as it appears throughout Schopenhauer's works), describes any system which denies the dichotomy of the ideal and the real, asserting the absolute and unconditioned reality of the world of representations (or any part thereof): realism argues that the appearance of the thing as apprehended by the knowing subject is absolutely actual prior to and independent of that knowing subject, and thus that an absolute knowledge (in some metaphysical or theological capacity) precedes our merely conditional and subjective knowledge of the world through experience (and thus the condition of epistemology is lifted from knowledge, but the elucidation of the simplest functions of apprehension becomes reliant on religious and metaphysical principles as their medium). By this usage, Locke is more properly described as an idealist, and Hegel as a realist, though one shall more likely read the opposite through the common abuse of the terms. Empiricism and idealism are thus in no way mutually exclusive (rather, for Schopenhauer, they are compatible), but nor do they appear (in the history of philosophy at large) as necessarily interdependent; on the contrary, the association of idealism with anti-empiricism (manifested variously as theories of "Innate Knowledge" {e.g., Plato}, or of an "Absolute Knowledge" existing independently of the mind of man [but interfering with it]) {e.g., Hegel and (less consistently) Aristotle} is so strong in the minds of academics, that many automatically assume that any dichotomy established between appearance and being-in-itself must be a contrivance leading to the dismissal of all empirical measurement of the appearance from further philosophical consideration. This is not the case for Schopenhauer, and any confusion of his method with Kant's (of rejecting all proof based on experience from philosophy to address the latter with arguments "purely a priori") will lead the student very far astray. Plato is thus correctly called an idealist in that he separates the world into one of "being but never becoming" and one of "forever becoming but never being", explaining the being-in-itself of the latter as having its basis in the former (which is outside of the phenomenon, and thus has itself no appearance, yet is its root, and is the kernel of the nature of the appearance); additionally, Plato makes the ideal the primary, and the real the secondary or conditional reality; but what leads to endless confusion in the classroom, and what differs fundamentally from Schopenhauer, is that Plato makes the "Immortal soul" and its mythical world the seat of the ideal, rather than the mere organs of the human brain (no professor relishes the task of differentiating Plato's sense of Idea from the usage of "idea" in common parlance, wherein it means only "concept in the mind"), and on this basis Plato denies the empirical basis of knowledge, referring instead to an innate knowledge of an other-worldly source whereof phenomenological reality merely "reminds" us. There is no justification for calling Hegel an idealist in the strictest sense of the term; rather, his historicism relies on an obtuse realism (I leave my reader to investigate Schopenhauer's comment on this point: WWR, vol. ii, pg. 442-4). Against the presumptions following from idealism's popular association with Plato and anti-empiricism in the Platonic mould (not to mention the confusion fomented by the Marxian usage of the term), we must insist that idealism does not preclude empiricism, but rather, in so far as an epistemology ought to precede and condition every science (i.e. if it be granted that an understanding of what knowledge is, and what are its limits, ought to guide us in our evaluation and application of that knowledge), a solution to the problem of the ideal and the real stands in relation to every thoroughgoing empiricism as its indispensable proviso.

Schopenhauer is thus an Idealist{6}, yet estranged from the development of "German Idealism" as it is known in the universities:

Spinoza ⟼ Leibniz, Wolff ⟼ Kant ⟼ Fichte, Schelling ⟼ Hegel

This "estrangement", however, does not amount to an unqualified mutual antagonism; the anti-empiricism which sets the above sequence of speculative Idealists apart from Schopenhauer's critical Idealism has its most significant exception in certain aspects of Kant's work, which, to an extent we shall later define, was a requisite influence upon the empiricistic development. Further, without emending our statement of the disassociation of the critical and the speculative movements in general, we could make a considerable digression to explain Schopenhauer's relation to each of these thinkers in particular; for instance, while Schopenhauer's philosophy differs very fundamentally from Spinoza's, he holds Spinoza's work in much higher regard than any of the subsequent, derivative pantheists, often describing it as an advance over previous misconceptions in philosophy in certain specific elements, and characterizing the whole in a more balanced way than his attacks on Fichte, Schelling or Hegel ever allow. In the following passages Schopenhauer describes the opposition of anti-empiricists to the development of the critical tradition's approach to the problem of the ideal and the real (an approach which Schopenhauer considers himself to have put to its final purpose, solving the problem for all time), and in so doing describes his own philosophy's place in relation to both the critical and the speculative traditions. In the first excerpt following, the distinction I proposed earlier is demonstrated as Schopenhauer identifies Malebranche as an Idealist (on the basis of his effort to tackle the problem I have definitively paired to that term in general), but must differ from him in the same respect with which I have described Schopenhauer's disparity with Plato,{7} for Malebranche is an anti-empirical Idealist (explaining knowledge not as qualified by experience [as phenomenological in its basis, and thus referring the problem to an epistemological solution] but as an absolute, explicable only through a metaphysical speculative construction):

To dispose of [the problem of the ideal and the real], Malebranche first devised the system of occasional causes. He grasped the problem itself in its whole range more clearly, seriously, and deeply than did Descartes. The latter had assumed the reality of the external world on the credit of God; and here, of course, it seems strange that, whereas the other theistic philosophers endeavour to demonstrate the existence of God from that of the world, Descartes, on the contrary, proves the existence of the world first from the existence and trustworthiness of God; it is the cosmological proof the other way around. Here too Malebranche goes a step farther and teaches that we see all things immediately in God himself. This certainly is equivalent to explaining something unknown by something even more unknown. Moreover, according to him, we not only see all things in God, but God is also the sole activity therein, so that physical causes are so only apparently; there are mere causes occasionnelles. (Recherches de la vérité, Livre vi, pt. 2, ch. 3) And so here we have essentially the pantheism of Spinoza, who appears to have learnt more from Malebranche than from Descartes. [P&P, vol. i, pg. 5]

In the pages following the passage above, the same criticism is applied to Leibniz and Spinoza, who, deriving their treatment from Malebranche, demonstrate an awareness, if only a very partial and inadequate one, of the same problem; but again Schopenhauer rejects their posited solutions as anti-empirical; he rejects their establishment of the perception of the world on the presumed medium of God, and thus the posit of a mystical (rather than epistemological) correlation between object and subject, and between the representation and the thing-in-itself:

[T]he harmonia praestabilita of Leibniz [appears again with Spinoza,] only here the represented world and the objectively existing world do not remain wholly separated, as with Leibniz, corresponding to each other merely by virtue of a harmonia, regulated in advance and from without, but actually they are [posited as] one and the same. Therefore we have [with Spinoza, ultimately] a complete and absolute realism, in so far as the existence of things corresponds exactly to their representation in us, since indeed [he claims that] both are one. Accordingly... the things-in-themselves [are claimed to] manifest themselves as extensa, in so far as they appear as cogitata, that is to say, in our representation of them. (Incidentally, here is the origin of Schelling's identity of the real and the ideal.) Now all this, properly speaking, is based only on mere assertion. The exposition is difficult to understand through the ambiguity of the word Deus that is used in a wholly improper sense; and so it loses itself in obscurity... The obscurity... in Spinoza's doctrine arises from his not proceeding impartially from the nature of things as he finds them [i.e. empirically], but from Cartesianism, and accordingly from all kinds of traditional concepts such as Deus, substantia, perfectio, and so on, which he attempted in roundabout ways to bring into harmony with his notion of truth. Very often he expresses the best things only indirectly... and almost allegorically. [For] on the other hand, Spinoza [occasionally] evinces an unmistakable transcendental idealism, namely a knowledge, although only general, of the truths expounded by Locke and particularly by Kant, hence [of] a real distinction between the phenomenon and the thing-in-itself, and a recognition that only the phenomenon is accessible to us. [(A list of specific passages from Spinoza follows) P&P, vol. i, pg. 10-12]

The above passage is significant in several respects. Firstly it shows, against Schopenhauer's reputation as an uncompromising curmudgeon, that he is more than willing to extend praise and recognition even to those philosophies that he considers thoroughly wrong as a systemic whole for whatever correct advances they have posited, if only as isolated and unsupported claims;{8} thus, while Spinoza only occasionally and inconsistently recognises the Idealist problem at the root of knowledge, and is doubly estranged from Schopenhauer as being both a realist (in his final conclusions) and an anti-empiricist, the scattered passages more in tune with Locke's critical Idealism (and, to some extent, Kant's -- as we shall discuss subsequently) are granted both praise and thoughtful, balanced criticism in the pages which follow the quote above.{9} Secondly, we find above the affirmation of the compatibility of Idealism with empiricism, illustrated with the prominent example of Locke; Schopenhauer's concord with Locke is again expressed below, in opposition to the various anti-empirical Idealists; but we also begin to see the one respect in which Schopenhauer diverges from Locke, which shall draw our attention to the importance of Berkeley and Kant:

The closest affinity between Malebranche, Spinoza, and Berkeley is unmistakable. We see them all start from Descartes in so far as they retain and try to solve the fundamental problem that is presented by him in the form of a doubt concerning the existence of the external world. For they are concerned to investigate the separation and connection of the ideal and subjective world, given solely in our representation, and the real objective world, existing independently and thus in itself. Therefore this problem is, as I have said, the axis on which the whole of modern philosophy turns. Now Locke differs from those philosophers in that, probably because he is under the influence of Hobbes and Bacon, he attaches himself as closely as possible to experience and common sense, avoiding as far as possible hyperphysical hypotheses. For him the real is matter... with him the real, i.e. matter, generates in the knower representations or the ideal through "impusle", i.e. through a push or thrust. Thus we have a thoroughly massive realism which by its very exorbitance called forth contradiction and gave rise to Berkeley's idealism. [...] However, even Locke does not overlook that fundamental problem, namely the gulf between the representations within us and the things existing independently of us and thus the distinction between the ideal and the real. But speaking generally, he disposes of it with arguments of sound but rough common sense, and by reference to the adequacy of our knowledge of things for practical purposes, which obviously has nothing to do with the case and only shows how very inadequate to the problem empiricism remains. But now it is just his realism that leads him to restrict what corresponds to the real in our knowledge to qualities inherent in things, as they are in themselves, and to distinguish these qualities from those that are connected merely with our knowledge of them, and thus only with the ideal. Accordingly, he calls the latter secondary qualities, but the former primary. This is the origin of the distinction between the thing-in-itself and phenomenon, which later on in the Kantian philosophy becomes so very important. [P&P, vol. i, pg. 16-17]

...Spinoza had already opposed to the whole Cartesian dualism his doctrine [that the thinking substance and the extended substance are one and the same,] thereby showing his great superiority. Leibniz, on the other hand, remained astutely on the path of Descartes and othodoxy. But then this evoked the endeavour of the admirable Locke which was so thoroughly wholesome for philosophy; he finally insisted on investigating the origin of concepts and made the sentence "no innate ideas" the basis of his philosophy, after he had discussed it at length. The French, for whom his philosophy was elaborated by Condillac, soon went too far in the matter, although for the same reason, since they put forward and urged the sentence penser est sentir. Taken absolutely, this is false; yet in it is to be found the truth that all thinking partly presupposes feeling, as an ingredient of the intuitive perception that furnishes it with its material, and that thinking, like feeling, is itself partly conditioned by bodily organs. And thus just as feeling is conditioned by the nerves of sense, so is thinking by the brain, and the two are nervous activity. Now even the French school did not stick so firmly to this sentence [penser est sentir, "to think is to perceive"] for its own sake, but again with a metaphysical, and indeed a materialistic purpose [in mind]. In the same way [that] the Platonic, Cartesian, Leibnizian opponents had stuck to the false proposition that the only correct knowledge of things consists in pure thinking [without any reference to experience], likewise with a metaphysical intention, namely to prove with it the immateriality of the soul. Kant alone leads us to the truth from these two false paths{10} and from a dispute wherein both parties do not really go to work honestly. ...Kant says: "Certainly there is a pure knowledge of reason, that is, cognitions a priori that precede all experience and consequently a thinking that does not owe its material to any knowledge that is produced by means of the senses." But although not drawn from experience, this very knowledge a priori has value and validity only for the purpose of experience. For it is nothing but the awareness of our own knowledge-apparatus and of the structure and mechanism thereof (brain-function) or, as Kant expresses it, the form of the knowing consciousness itself. [...] Now through this, all that metaphysical psychology [the anti-empiricism of innate ideas, etc.] falls down, and with it all Plato's [theories of knowledge as] pure activity of the soul. For we see that knowledge without the intuitive perception that is brought about by the body has no material, and consequently that the knower as such, without the presupposition of the body, is nothing but an empty form; not to mention that all thinking is a physiological function of the brain, just as digestion is of the stomach. [P&P, vol. i, pg. 45-6]

Thus while Schopenhauer agrees with Locke's fundamental standpoint in the main, he diverges from him in conditioning his empiricism with the Kantian notion of a priori forms of knowledge preceding and shaping human understanding (which is, as the quote above makes abundantly clear, as much a "biological" as a "transcendental" condition of the understanding);{11} we should note, however, that Schopenhauer's understanding of the a priori is more strictly limited to this empirical purpose than Kant's, which (most obviously in Kant's ethical construction of "a priori aphorisms") extends well beyond this into metaphysical speculation, and forever hints at a spiritual rather than biological basis for the "transcendental" forms of knowing.{12} Schopenhauer likewise regards Berkeley as an advance from the fundamental standpoint established by Locke, but Berkeley's investigations, as much as they extended our understanding of the ideal, remaindered the explanation of the real wholly to theology, and thus in another sense were a regression to an older anti-empiricist doctrine rendering God as the medium of knowledge:

Although coming later and already with the knowledge of Locke, Berkeley consistently went farther on this path [opened by Descartes in the modern era], and thus became the originator of the proper and true Idealism [i.e. the beginning of the proper and true solution to the problem of the ideal and the real], that is, of the knowledge that what is extended in and fills space, and thus the world of intuitive perception generally, can have its existence as such absolutely only in our representation, and that it is absurd and even contradictory to attribute to it, as such, another existence outside all representation and independently of the knowing subject, and accordingly to assume a matter existing in itself. This is a very true and deep insight, but his whole philosophy consists in nothing but this. He had hit upon and clearly separated the ideal; but he did not know how to find the real, about which he did not trouble himself very much and expressed himself only occasionally, piecemeal, and incompletely. With him God's will and omnipotence are directly the cause of all the phenomena in the world of intuitive perception, that is to say, of all our representations. Real existence belongs only to knowing and willing beings, such as we ourselves are: hence these, together with God, constitute the real. [...] Also in common with his predecessors, he regards God as better known than the actual world before us; and he therefore regards a reduction to him as an explanation. [P&P, vol. i, pg. 14]

The relations between Schopenhauer and these thinkers are again treated in the second essay's §12 [P&P, vol. i, pg. 67-78], where the same historical development is recounted, but this time in reference to the problem of substance and essence,{13} rather than that of the ideal and the real; if the reader should investigate, they would find there again the affirmation of my reading of Schopenhauer's relation to Leibniz, Spinoza, Locke, Berkeley and Kant, with only a slightly different vocabulary revealing Schopenhauer's partial affinity or total disaffection with each respectively (determined by the same requirements of [1] approaching the problem of idealism [2] on the empiricist path). The section speaks of "starting from the subjective standpoint" in an equivalent sense to what we described earlier as "conditioning knowledge with its phenomenological basis" --because, in the problem of substance and essence, to begin with the subject is to admit that the problem is first and foremost one of epistemology, just as the empirical conditionality of representation referred us to empistemology in the formerly treated problem--{14} and then the section works through roughly the same schedule of advances and setbacks (from the vantage of a closely related but separate problem) to which Schopenhauer considers the creation of his own work beholden (in its presumed importance as the final solution). I reproduce here only a few words from the section's conclusion, from which my reader shall see at once that the whole is in agreement with all that has been said to this point:

Berkeley was, therefore, the first to treat the subjective starting-point really seriously and to demonstrate irrefutably its absolute necessity. He is the father of idealism... Thus even Locke started from the subjective in that he conceded a great part of the properties of bodies to our sense-impression. [...] [T]hrough this preliminary distinction of the subjective element from the objective in intuitive perception [Locke] led directly up to Kant who, following his direction and track in a much higher sense, managed clearly to separate the subjective side from the objective. [P&P, vol. i, pg. 77]

My reading is again affirmed in §13 of the same essay, where the historical development of the understanding of the mutual opposition and interdependence of the ideal and the real is treated once more, but this time organized thematically (instead of chronologically) as it relates to Kant's philosophy. The same points are reprised, but with greater emphasis and a longer discussion granted to the a priori conditioning of empirical knowledge, and with the first positive statement (in the P&P) of what the often mentioned dichotomy of ideal and real actually is (along with various reflections on the ideality of time and other themes central to the Principle of Sufficient Reason and the WWR). As I cannot possibly reproduce the argument here, I can only encourage my reader to seek it out if he would dissent from my reading of Schopenhauer's place in the history of ideas, which in the following passage we have the better part of stated in brief, and by Schopenhauer's own pen:

...it will be seen that Locke, Kant, and I are closely connected since in the interval of almost two hundred years we present the gradual development of a coherent, consistent, and uniform train of thought. David Hume may also be considered as a connecting link in this chain although, properly speaking, only with regard to the law of causality. [P&P, vol. i, pg. 88]

An important passage follows the above excerpt, describing the common thread (of what I call critical idealism) running through Hume, Locke, and select aspects of Kant{15} (to which list Schopenhauer would, again, add his name in conclusion) [ibid., 88-90]; Hume is here credited with expounding the ideality of causality (the necessary consequence of the ideality of space and time), and thus with advancing (in one aspect) the problem of the ideal and the real; Hume's importance to Schopenhauer is considerably greater than merely this, however, as his critique of the causality of concepts (of certainty) prefigured Schopenhauer's resolution of the criterion of truth (for which Hume is appropriately praised in the respective sections of the Principle of Sufficient Reason and the WWR). Of the names I have included in critical Idealism's "gradual development of a coherent, consistent, and uniform train of thought", only one remains who was not treated at length nor added explicitly to this list in the P&P; this is Thomas Hobbes, who is mentioned in these essays only in passing as a requisite antecedent to Locke [reproduced above]. Hobbes was in several respects an important influence, however, prefiguring elements of Schopenhauer's epistemology, psychology and being quoted and alluded to many times over in Schopenhauer's ethical and political writings; his brief treatment in the sections to which I have thus far referred follows necessarily upon their organizing principle, the presentation of the problem of Idealism as "the axis on which the whole of modern philosophy turns" -- whereby Hobbes may be fairly represented as little more than a necessary prequel to Locke, but certainly as nothing less. We shall return to Hobbes on consideration of Schopenhauer's ethics and politics; what remains to be addressed in this section (with the positive statement of Schopenhauer's relation to these critical Idealists complete) is some negative statement as to his relation to the later proponents of "German Idealism", and a reckoning of Kant's double role in touching off new developments in both traditions.

It was for the specific purpose of precluding the confusion of his philosophy with the speculative idealism of Fichte, Schelling and Hegel that Schopenhauer wrote the appendix to the "Sketch of a history of the Doctrine of the Ideal and the Real" (his estrangement from Descartes, Leibniz and Spinoza, and the other, earlier Idealists being demonstrated in the essay before it, and again, on a broader time-line, in that which follows). While there is not an inch of ambiguity left for the historians to exploit by Schopenhauer's repeated attacks on the neo-Kantians throughout the WWR and its auxiliary essays (On the Will in Nature, Die Beide Grundprobleme der Ethik, etc.{16}), the authorities have everywhere attempted to sympathetically associate Schopenhauer with Fichte and/or Schelling, often enough reducing him to a mere digression in the "German Idealist" development culminating in Hegel -- ignoring the principles of the very philosophy they pretend to eulogize. Höffding and Aiken seem to have pioneered (or at any rate have popularized) the former trend, which the authors of the English language in more recent times have taken to its utmost extreme, in defiance of the evidence of which every page of Schopenhauer's philosophy is a part. Fortunately, Schopenhauer has left us a ready instrument to shame all these rationalizing professors and biographers, in that we can refer with great convenience to this appendix, which sets the matter forth in all its simplicity, and debunks any and every such effort to subsume his works in those of his adversaries; I recommend this brief passage in its entirety [P&P, vol. i, pg. 21-8] as an antidote to the mistakes and misrepresentations which have become the rule in the literature, and would make this the required reading of any student before they should consult a secondary source on our subject. In the following excerpt we find Schopenhauer's double enmity for the neo-Kantians expressed by the same paired criteria by which he qualified his estrangement from Spinoza, and conditioned his praise for Locke and so on for the others (namely, the requirement that philosophy [1] approach the problem of Idealism [2] on the empiricist path): Fichte, Schelling and Hegel are rejected as anti-Idealist (in that they deny the dichotomy of ideal and the real) as well as anti-empirical (each with their own colourful theory of an absolute knowledge, a "knowledge unconditioned by experience or the brain" as compared to a "digestion without food or a stomach" above{17}); but to this is added the charge of intellectual dishonesty [pg. 21-24], as all these thinkers begin from a knowledge of the problem inherited from Kant, only to deny its existence, or to pretend that such authoritative denials constitute its solution:

Thus after Kant had more than ever accentuated the great problem of the relation between what exists in-itself and our representations, and so had brought it a great deal nearer to solution, Fichte came forward with the assertion that there is nothing more behind the representations and that these are simply products of the knowing subject, of the ego. While attempting in this way to outdo Kant, he produced merely a caricature of that philosopher's system... he entirely abolished the real and left over nothing but the ideal.{18} Then came Schelling who, in his system of the absolute identity of the real and the ideal, declared that whole difference to be of no account and maintained that the ideal is also the real and that the two are identical. In this way, he attempted again to throw into confusion that which had been so laboriously separated by means of a slow and gradually developing process of reflection, and to mix up everything. The distinction of the ideal and the real is... boldly denied in imitation of the above-censured errors of Spinoza. At the same time, even the monads of Leibniz, that monstrous identification of two absurdities, thus of the atoms and of the indivisible, originally and essentially knowing individuals called souls, are again fetched out, solemnly apotheosized, and made use of. Schelling's philosophy bears the name of the philosophy of identity because, following in Spinoza's footsteps, it abolishes three distinctions which he too had abolished, namely that between God and the world, that between body and soul, and finally also that between the ideal and the real in the intuitively perceived world. [...] In keeping with all this, metaphysics was by Schelling identified with physics and accordingly the lofty title of Von der Weltseele was given to a merely physico-chemical diatribe. All really metaphysical problems that untiringly force themselves on human consciousness were to be silenced through a flat denial by means of peremptory assertions. Nature is here just because it is, out of itself and though itself; we bestow on it the title of God, and with this it is disposed of; [as with Spinoza, reduction of a problem to the name of God is passed off for an explanation] ... The distinction between subjective and objective is [thus made out to be] a mere trick of the schools, like the whole Kantian philosophy, and this philosophy's distinction of a priori and a posteriori is [treated as if it were] of no account. Through his doctrine of the identity of the real and the ideal, Schelling had accordingly tried to solve the problem that was started [in the modern era] by Descartes, dealt with by all great thinkers, and finally brought to a head by Kant... [but he only] attempted to solve this problem by cutting the knot, in that he denied the antithesis between the real and the ideal. In this way he came into direct contradiction with Kant, from whom he professed to start. [P&P, vol. i, pg. 25-26]

...Schelling... followed in Fichte's footsteps which, however, he forsook in order to proclaim his own invention, the absolute identity of the subjective and the objective, or of the ideal and the real. This implies that everything that rare minds like Locke and Kant had separated after an incredible amount of reflection and judgement, was to be again poured into the pap of that absolute identity. For the teaching of these two thinkers may be very appropriately described as the doctrine of the absolute diversity of the ideal and the real, or of the subjective and the objective. When once incomprehensibility of speech was introduced by Fichte and the semblance of profundity was put in place of thought, the seeds were scattered which were to result in one corruption after another and finally in the complete demoralization of philosophy and thus of the whole of literature, which has arisen in our day. Schelling was followed by a philosophical ministerial creature, to wit Hegel, who for political and indeed mistaken purposes was from above dubbed a great philosopher --a commonplace, inane, loathsome, repulsive, and ignorant charlatan, who with unparalleled effrontery compiled a system of crazy nonsense that was trumpeted abroad by mercenary followers, and was actually regarded as such by blockheads, whereby such a complete chorus of admiration arose as had never before been known. [ibid. pg. 95-6]

Now the inaccurate expression [of using the terms "thinking" and "being" in such a way as to exclude "perceiving" from epistemological concerns] borrowed by Schelling from Spinoza, was later used by that insipid and inane charlatan Hegel, who in this respect appears as Schelling's buffoon, and it was so distorted that thinking in itself in the proper sense and hence concepts were to be identical with the essence-in-itself of things. Therefore what is thought in abstracto, as such and directly, was to be identical with what is objectively present in itself, and accordingly logic was to be the true metaphysics. ...[T]his absurdity was supported by a second, namely that we did not think, but the concepts, alone and without our assistance, completed the thought process, which was, therefore, called the dialectical self-movement of the concept, and was now to be a revelation of all things in et extra naturam. [...] After the manner of Spinoza, Schelling had given the world the title of God. Hegel took this in the literal sense. Now as the word really signifies a personal being who, together with other qualities absolutely incompatible with the world, has also that of omniscience, this too was now transferred by Hegel to the world. Naturally it could not find any other place than the simple mind of man, whereupon he needed only to give free play to his thoughts (dialectical self-movement) in order to reveal all the mysteries of heaven and earth, namely in the absolute gibberish of the Hegelian dialectic. There is one art that Hegel has really understood, and that is how to lead Germans by the nose. [ibid. pg. 27-28]

I say again that Schopenhauer stands in unmitigated, diametric opposition to the "three sophists" castigated above, precisely because they belong to the other pole of "the axis on which the whole of modern philosophy turns": Schopenhauer regards as his adversary any who would deny the "absolute diversity of the ideal and the real", or would proffer a theory of "absolute knowledge", "innate ideas" or what-have-you in place of the empiricist epistemology established by Hobbes and Locke (and, Schopenhauer would argue, developed further by Kant) -- the sheer repetition of this point throughout the P&P and in several parts of the WWR [e.g. WWR, vol. ii, ch. i and ch. xviii; and vol. i, pg. 417-21] should leave us in no doubt as to its essential importance. In addition to this, one can easily enough come up with a great number of secondary, normative differences distinguishing the sprit of critical idealism from that of its speculative counterpart (e.g., individualism vs. statism, hypothetical-deductive method vs. teleological claims, etc.) following upon their essential distinction; but, significantly, this does not equate to any one, simple political dichotomy.

[...] [we have thus far discussed] only a single historical development (the paramount importance of which was Schopenhauer's own contention) and [have not attempted an] exhaustive schematization of Schopenhauer's influences; certainly a great many of Schopenhauer's sources may be named who did not contribute to the problem of the ideal and the real, and thus have not been addressed in this "history of ideas" (Giordano Bruno, Rousseau, Pascal, etc.). Further, our discussion has been restricted to modern Europe (aside from a brief mention of Plato), and has thus omitted Schopenhauer's many comments on the related arguments among the ancients,{19} but more importantly, we have excluded the stunning analogue to Schopenhauer's solution to the problem of the ideal and the real which is to be found in the epistemology of the Hindu Upanishads. It would be wholly extraneous to treat this at length here, but, of the three sources to which Schopenhauer directs our attention in the preface to the WWR [pg. xv-xvi], both Plato and (as I shall discuss presently) Kant may for the most part be reduced to inspirations rather than influences, whereas the Upanishadic and Buddhist philosophies alone share in Schopenhauer's solutions to the problems of epistemology and metaphysics; despite Schopenhauer's repeated gratitude to Plato and Kant's works for having prepared the way for his own, only a very limited common ground may ever be found between them, and Schopenhauer rather less appeals to the authority of either figure (as it appears in their writings) than to his own interpretation thereof, relying in both cases on a substantial body of criticism; thus, the grano salis with which all his praise for Plato is to be taken is to be found in the historical essays of the P&P{20} and the WWR §49,{21} and that for Kant in the WWR's appendix, making the congruencies with the eastern religions all the more important by comparison.{22} We now return to a question I had formerly deferred, and ask [...] "What was Kant's relation to Schopenhauer, and why is he [so often] depicted as a stage in the progression of the speculative idealists toward Fichte, Schelling, and Hegel?"

Schopenhauer's relation to Kant is treated exhaustively in the appendix to the WWR's first volume, and the same question is answered with greater brevity in the same pair of historical essays from which we have already quoted so extensively. Certainly the best pretext for associating Schopenhauer with "the three sophists" of the opposite tendency has been to point out their common appeals to Kant's authority, which in each case is conditioned by a common conceit as to the importance of their own works over and against it ([i.e.,] emending or superseding it); however, this can never be more than a pretext: that Fichte, as much as Schopenhauer, claimed to have completed the work that Kant began is hardly a firm measure of association; if anyone were to bother to look beyond words to meanings they would soon find that the two have a mutually opposed understanding of what Kant's significance is, and that they draw almost exclusively from different aspects thereof; likewise, the bare similarity of words which is used to compare Schopenhauer to Schelling could as well be extended to all Germans of the period, as philosophy had in those times a limited vocabulary in the living languages, and owed most of its German terms to the recent coinage of either Wolff or Kant. Schopenhauer did not leave the historians any room for confusion on such matters:

My works had scarcely excited the attention of a few, when the dispute as to priority arose with regard to my fundamental idea, and it was stated that Schelling had once said "willing is original and primary being", and anything else of this kind that could be adduced. With regard to the matter itself, it may be observed that the root of my philosophy is to be found already in the Kantian, especially in Kant's doctrine of the empirical and intelligible characters, but especially in the fact that, whenever Kant brings the thing-in-itself somewhat nearer to the light, it always appears through its veil as will.{23} `...[A]ccordingly I have said that my philosophy is only his thought out to the end. Therefore we need not wonder if the philosophemes of Fichte and Schelling, which also start from Kant, show traces of the same fundamental idea, although they there appear without sequence, continuity, or development... it may be said on this point that, before every great truth has been discovered, a previous feeling, a presentiment, a faint outline thereof, as in a fog, is proclaimed, and there is a vain attempt to grasp it... Accordingly, it is preluded by isolated utterances; but he alone is the author of a truth who has recognized it from its grounds and has thought it out to its consequents. [P&P, vol. i, pg. 132-3]

A straightforward description of Schopenhauer's derivation from Kant (presenting Kant's significance as building upon the development through Locke, Hume, etc.) in contradistinction to that of Fichte, Schelling and Hegel runs through pg. 88-97 of our familiar sourcebook, the P&P, vol. i; this begins with another segment of the historical argument with which my reader has, by now, become thoroughly acquainted:

Locke, as well as Condillac and his disciples ... argue and indicate that a sensation ... must correspond to its cause outside our body, and also that the differences of such effects (sense-impressions) must correspond to those of the causes, whatever these may ultimately be; from this results the distinction between primary and secondary qualities previously alluded to. With this they end, and for them an objective world now stands out in space, a world consisting of nothing but things-in-themselves which are indeed colourless, odourless, noiseless, neither warm nor cold, and so on, but which are nevertheless extended, formed, impenetrable, movable, and countable. But the axiom itself, by virtue whereof that transition from the inner to the outer and that whole derivation and installation of things-in-themselves have taken place, thus the law of causality, has been assumed by them, as by all previous philosophers, to be self-evident, and its validity has been subjected to no investigation. Now Hume directed on to this his skeptical attack by doubting the validity of that law. For he stated that experience whence, according to that very philosophy, all our cognitions were said to be derived, could never furnish us with the causal connection itself but always only with the mere succession of states in time ... which, precisely as such, would always prove to be either contingent or accidental and never necessary. Now this argument, so opposed to common sense yet not easy to refute, induced Kant to investigate the true origin of the concept of causality. He found this to reside in the essential and innate form of our understanding itself and hence in the subject, not the object, for it was not first brought to us from without. Now in this way, the whole of the objective world [left over as "primary qualities" by] Locke and Condillac was drawn back again into the subject [...] Locke's objective world of things-in-themsleves had been changed by Kant into a world of mere phenomena in our cognitive apparatus, and this the more completely in that the space in which they present themselves and also the time in which they pass were shown by him to be undeniably of subjective origin. [P&P. vol. i, pg. 88-9]

However, Kant's conclusion that the thing-in-itself remains outside of representation to act as its basis did not follow on his principles; he was correct that "behind the representation there lies something represented" [ibid, 89], but he attempted to prove the nature of both by expounding a system of imperative a priori 'truths' (or 'laws'):

But just because these are a priori, they cannot lead to something independent of, and different from, the phenomenon or representation [P&P, vol. i, pg. 90; compare WWR, vol. i, pg. 502]

On this the endless inconsistencies and absurdities of the Kantian epistemology soon follow:

For the whole essential nature of the given phenomena, that is, of the corporeal world, is by no means a priori determinable by us; on the contrary, [the a priori] is merely the universal form of its phenomenal appearance, and this may be reduced to space, time, and causality, together with the entire conformity to law of those three forms. [P&P, vol. i, pg. 90-1]

Thus we find in these excerpts the affirmation of what I had posited earlier in regard to Schopehauer's derivation from Locke: Schopenhauer considers empiricist epistemology incomplete without a "transcendental critique", or, in other words, an understanding of the a priori forms conditioning our understanding (but, although Schopenhauer is certainly beholden to Kant for opening this path to philosophy, he restricts the a priori more strictly to this purpose, and does not dismiss the philosophical significance of knowledge-from-experience thereby). While Schopenhauer maintains that Kant's fundamental standpoint (in the Prolegomena to any Future Metaphysics) is correct, and that it indicates the correct route to the solution of the problem of the ideal and the real, the "neo-Kantians" addressed only its argumentation, and:

...instead of pursuing this course, [they] confused Kant's presentation with the essence of the matter; they believed that with the former the latter was refuted... and accordingly, with Schultze's attacks, they declared Kant's philosophy to be untenable, Thus the field was now free for sophists and humbugs. The first of this class to appear on the scene was Fichte, who, because the thing-in-itself had just been discredited, at once prepared a system without any thing-in-itself. Consequently, he rejected the assumption of anything that was not through and through representation, and therefore let the knowing subject be all in all or at any rate produce everything from its own resources. For this purpose, he at once did away with the essential and most meritorious part of the Kantian doctrine, the distinction between a priori and a posteriori and thus that [dichotomy] between the phenomenon and the thing-in-itself [, while adopting and exaggerating the worst mistake of Kant's doctrine: its marginalization (or exclusion) of empirical data (of all knowledge based in perception) through the proliferated role of the a priori forms of knowledge]{24}. [P&P, vol. i, pg. 94-5]

Schopenhauer's debt to Kant may be reduced to (1) the distinction of the phenomenon from the thing in itself, (2) the introduction of the a priori to the consideration of the problem of the ideal and the real, and (3) the separation of the empirical from the intelligible character in ethics;{25} but while these presented themselves as great inspirations, and set Schopenhauer on the path to his resolution of the dichotomies of subject-to-object and ideal-to-real (as well as anchoring his ethics -- in total opposition to Kant's), they appeared only very inconsistently and were poorly argued in Kant's works, where the real implications of his epistemology were rarely borne out through the rest of his philosophy, if they were even understood by Kant at all:

Precisely the same thing happened to Kant with the demonstration of the thing-in-itself as with the demonstration of the a priori nature of the law of causality; both doctrines are correct, but their proof is false. They belong to correct conclusions from false premises. I have retained both [conclusions], yet I have established them in an entirely different way and with certainty. [WWR, vol. i, pg. 503]

Thus we find in the WWR's appendix, after a compressed treatment of the same historical development of the ideal and the real we have described above [WWR vol. i, pg. 417-21], that while "Kant's greatest merit is the distinction of the phenomenon from the thing-in-itself" (an advance over Locke in so many ways), nonetheless:

Kant did not arrive at the knowledge that the phenomenon is the world as representation and that the thing-in-itself is will. [...] [Nor did he] deduce the thing in itself in the right way as I shall soon show, but [only] by means of an inconsistency; [...] [Nor did he] recognise the thing-in-itself directly in the will, but made a great and original step towards this knowledge [in his separation of the empirical from the intelligible character]. [WWR, vol. i, pg. 421-2 (underscore added)]

To the surprise of the first time reader of the WWR, on reaching the appendix we at last discover that this fellow Kant to whom Schopenhauer's praises have all been addressed in the foregoing pages was not at all the well-known historical personage, but merely a composite character to whom the authorship of the first section of the Prolegomena and a scant few passages of the Critique of Pure Reason{26} had been attributed (to the exclusion of all else); the skeptical spirit of the Kantian philosophy, which Schopenhauer has so rigorously propounded over and against that of speculative idealism, is to be found only in a few scattered lines, and is contradicted everywhere else. Schopenhauer's image of Kant as the demolisher of scholastic dogmatism (dealing "speculative theology and the rational psychology connected with it... their death blow") [Ibid., pg. 422-423] is conditioned by his total rejection of Kant's later writings, and the willing oversight of many sections even within the Critique of Pure Reason{27}, wherein the very conception of the a priori that Schopenhauer praises for prying open the old metaphysics (and laying it bare for empirical skepticism) is made a means for the erection of a new speculative dogmatism, and indeed cloaks it in a veil of inscrutability no less repugnant than the pseudo-theology of the dark ages. Schopenhauer comments that the Critique of Pure Reason's chapter on the Transcendental Ideal "at once takes us back to the rigid scholasticism of the middle ages. We think we are listening to Anselm himself." [WWR vol. i, pg. 507] but a few pages later he congratulates Kant for "the complete overthrow of that philosophy":

[Kant] eliminated theism from philosophy; for in philosophy, as a science and not a doctrine of faith, only that can find a place which either is empirically given or is established through tenable and solid proofs. [Ibid., pg. 510]

This lionized vision of Kant is contradicted once again in the essay On the Basis of Morality, wherein Schopenhauer attacks Kant's "imperative" system of ethics as theistic, disparaging it as no more philosophically tenable (beneath its veil of circumlocutions) than the bald commands of a Moses or a bloodthirsty Mesoamerican idol, and goes further to explicitly identify it with the worst elements of philosophy in the dark ages [§4, §6, especially the "note" ending §6] -- descrying in Kant's ethics the very obscurantist rational psychology whereof the same author is elsewhere supposed to be the great extirpator!{28} There is an obvious conflict between the Kantian philosophy as it exists on the page and the inspiring muse which Schopenhauer found in it; the simplest and truest statement which Schopenhauer made on Kant's use and abuse of the a priori may be easily extended to Kant's other "most brilliant and potent discoveries" (distinguishing the empirical from the intelligible character, and the phenomenon from the thing in itself):

We sometimes see a doctor who has applied a remedy with brilliant success henceforth prescribe it for almost all diseases; I liken Kant to such a man. By separating the a priori from the a posteriori in human knowledge, he made the most brilliant and potent discovery of which metaphysics can boast.{29} Is there any wonder when he now tries everywhere to apply this method, this separation? [On the Basis of Morality, (6, pg. 61]

Unfortunately, "this method" of Kant's does not consist merely in a separation of a priori from a posteriori, but also in the rejection of the latter for the former; it is a doctrine of "pure reason" as the "source" of philosophical principles to the exclusion of any empirical basis. While the world as representation may be one of merephenomena (i.e. while we may never see the sun, but only the light cast by the sun) Kant inferred from this that philosophy should address itself not to those phenomena (the limited nature of which merely exhausts the entire world of experience, the basis of all knowledge, and the substance of every material and moral concern in every practical human endeavour) but instead to their ultimate basis outside of all perception, the things-in-themselves -- the "laws" concerning which should likewise be established without the uncertain study of those mere phenomena, but rather from the "pure" contemplation of our "a priori judgements". Thus Kant struck the whole world of human experience and emotion from the record of ethics like perjured testimony, and referred questions of human nature, of justice, of the rights of states and citizens respectively, not to the unkind (empirical) realities which occupied the minds of men like Hobbes, but rather to systems of imperative laws (laws describing not what is, but what ought to be) invented by pure speculation -- from which whole systems of political philosophy and jurisprudence were then spun out, first to suit the interests of the "liberal" bourgeoisie, and later those of the nation-state and the Prussian reactionaries. It is in Kant's own philosophy that we find the origin of "that characteristic fault of the Germans to look in the clouds for that which lies at their feet", which Schopenhauer so despised among the political philosophies of his own generation. It is therefore something of an irony that Schopenhauer exempts Kant from much of the criticism delivered to the Neo-Kantians, but is equally applicable to Kant's own written works, for the sake of the three "brilliant and potent discoveries"{namely... 30} for which he is indebted to him; 

for it is not merely the proofs of these three concepts which were inadequate to Schopenhauer, but their entire application is incompatible with his philosophy -- leaving over only the barest germ of inspiration which may be attributed to both Kant and Schopenhauer in common. With the exception of these three points [listed above], and Schopenhauer's general sympathy for Kant's polemics against religion and teleology (largely derived from Hume) [