“Some see the glass as empty, I see a glass full of ether.”
— J. Cole
We are entangled in a love-hate relationship with Immanuel Kant. Throughout the last two centuries, those who have an affinity for the philosophical task have directly or indirectly been involved with his postulations, mainly those pertaining to his critical period: from the publication of the first edition of the Critique of Pure Reason (1781) onward until the end of that decade. In the first Critique, the curly-headed Professor from Königsberg—as Friedrich Nietzsche dubbed him—sought to delineate the rules by which philosophers were to inquire into the intellectual endeavor known as metaphysics. Following Kant, any possible metaphysical speculation would only be reasonable inasmuch as it abides by the laws of our transcendental understanding[1]; in other words, as long as such speculation refers either to potential experience and/or logically proceeding by deduction. By positing such rules, Kant ruined the party of metaphysical speculation. However, his systematic proposal was not without internal contradictions or predicaments. Seeking to remedy his critical system, the later years of his life were arduously dedicated to correcting it, and many loose, fragmentary and (some argue) eccentric pages of work were wrought, later compiled into a posthumous publication: the Opus Postumum. The following essay offers an account of how certain aspects of his critical period enter in dialogue with specific passages in the Opus Postumum, and ultimately, of how this relation between Kant’s critical and posthumous work offers a glimpse of an overarching, hermeneutic reading of Kant. The thread that ties together the following paragraphs is the thing in itself, a procedural concept which progressively set the stage for the concept of the ether, a methodological artifice that Kant postulates in the Opus Postumum with the intention of correcting some of the Critique’s shortcomings.
At risk of attempting to give an exhaustive account of what Kant’s concept of thing-in-itself [Ding an sich] refers to and where it arises from within the context of the philosophical tradition, we could briefly establish that it alludes to a thing which stands independent of any experience of it. As opposed to any phenomenon, which is any event, thing or fact that appears before our perception in space and time, a thing in itself is imperceptible to any possible account of experience. How could one hope to reasonably speculate on something which one has no experience of? Kant’s concept refers to transcendental things, in other words, to things that either precede or surpass the realm of experience, things such as: what is usually referred to as the soul, that which is the cause of one’s subjectivity and individuality; also, the world, the place where our subjectivities converge and the rules which govern their nature; and finally, that which is at the bottom of all possible causal relationships (including thought itself), so what is usually referred to when one speaks of God. As Kant wrote, these three entities, “God, the world, and the thinking being in the world (man),” are all posited as examples of things in themselves in the sense that they are by definition at the fringes of any possible direct experience of them.
A few years following the publication of his first Critique, in a now famous article entitled “Answering the Question: What is Enlightenment?”, Kant wrote, “Have the courage to use your own reason! (in Latin sapere aude).” Following Kant’s maxim implies analyzing his works not positively, but critically. Consequently, instead of reading him by means of his authority as a canonical figure in the history of philosophy as intermediary, Kant—as any other author—ought to be subject to the trial of having to answer the critical question: how do you know that which you claim to know? In other words, how could Kant himself reasonably write about things in themselves?
For Kant, we share no ontological ground with things in themselves. It is out of the question to speculate on them reasonably. When digressing around things in themselves, Kant elaborated not on how they are, what they ought to be, or how we can know them. Rather, he spoke about things in themselves as a boundary concept[2] that operates as a logical—albeit not ontological—necessity.[3] If no person can ever give an account for how a thing is in itself, then consequently, nobody can ever reasonably claim that things in themselves occupy the realm of practical knowledge.[4] Things in themselves do not exist beyond their use as a methodological tool, a procedural resource, an unavoidable logical object and a didactic motif that helps explain Kant’s proposed nature of reason.[5] Although such a concept is an epistemological possibility of reason, it’s not an empirical reality, and should not be employed as an artifice that could be used to logically explain the world in a platonic or otherwise metaphysical sense. It was by rejecting the possibility of scientific inquiries into metaphysics that Kant’s critical project ruined the party of metaphysical speculation — a party he would later attempt to animate again in the Opus Postumum.
Due to the epistemological complexities of a concept as problematic[6] as the thing in itself, by the second edition of the Critique, Kant had to correct many of the postulations that surrounded it.[7] The methodological resource of the thing in itself is not only one of the main conceptual actors in Kant’s transcendental system, but ultimately, it will become an object of further digression, refutation and sublation within the overarching conceptual landscape of German Idealism. Many of Kant’s contemporaries and successors who commentated on his work, such as F. H. Jacobi, K.L. Reinhold, J.G. Fichte, F. J. Schelling and G.W. Hegel, among others, postulated their own nuances and differences pertaining to their respective conceptions of the thing in itself. However, it is unlikely that these authors encountered the drafts of the Opus Postumum, an unedited compilation of fragments that Kant started working on from 1796 well into old age, until his death in 1804.[8]
The Opus was ambitious. Too ambitious, perhaps. In it, Kant attempted to amend the conceptual gaps still latent in his transcendental system.[9] Some argue that, if completed, the Opus would have not only brought Kant’s idealist philosophy full circle, but also anticipated many of the presumed corrections undertaken by Fichte, Schelling and Hegel.[10] However, others propose that the Opus doesn’t represent much beyond a scant series of lucid aphorisms amid unclear, incomprehensible digressions, proceeding from a “senile” Kant who refused to put down his pen. The question of which one of these two categorizations of the Opus is correct ought to be answered according to each reader’s exegesis and approach to Kant’s previous work. Regardless of which answer one wishes to give, the Opus is nonetheless a captivating, novel, sometimes esoteric series of fascicles. Many of its pages reaffirm postulations previously put forth in the three Critiques (of Pure Reason, of Practical Reason, and of the Power of Judgment), while many others challenge fundamental passages and problematize their capacity to constitute a truly completed idealist system.
Throughout most of the Opus and specifically in the pages written from 1796 onward, a certain problematic concept looms over its fascicles.[11] It is an idea that goes by many names, and refers to an unheralded concept not mentioned in the first Critique. The philosopher writes about a novel conception of space with which he attempts to establish a cause-effect continuity between metaphysics and physics, a relation he names influxus physicus. Such a relation sought to serve as a transition between Kant’s theory of rationality and a possible method of bringing about the systematic knowledge of physics. However, this is not physics understood in a modern scientific sense, but rather physics understood as physis—as the presocratic philosophers Heraclitus and Parmenides elaborated on the term—which is the Greek concept for what we know as nature and the laws that govern it. Kant writes about a primordial material, about a “universally distributed matter occupying cosmic space”[12] whose properties serve as “the basis for the unified whole of all moving forces.” This material is “all-extended, all-pervasive, uniformly agitating itself throughout all parts of the space which it occupies or also fills by repulsion and infinitely enduring in this motion.”[13] Ether is what this concept is named. Kant sometimes calls it different things—like the caloric [Wärmestoff] or hypostatized space—and alludes to it through passages where he insists on the unity of the sensible realm: “There is only one space and only one time and only one material in which all motion will be found.”[14] In Classic mythology, the ether—which in Greek means ‘pure air’—was thought to be the fifth element, withdrawn from our senses but ubiquitous throughout the micro- and macro- cosmos. In Modernity, prior to Einstein’s theory of relativity, ether was regarded as the material medium that allowed the propagation of light and other electromagnetic radiation through the emptiness of the universe. Similarly, Kant claimed that his proposed iteration of the ether would fill space the way a substance does. In a passage of the Opus titled the Ether proofs, Kant postulates the reasoning as to why such a concept is necessary relative to the system of transcendental idealism, by means of his dynamic theory of matter. By contending with what he in the Opus conceptualized as the transition from metaphysics to physics, he attempts at deducing an organon or a series of epistemic principles that reconcile metaphysics—understood as transcendentally, the conditions of which are necessary for experience to happen and knowledge to occur—and physics—understood as physis, as the events, things, or facts that appear in nature and the laws that govern them, which are potential objects of knowledge. Part of such a transition from metaphysics to physics is the ether, which Kant also defines as “the basis of all matter as the object of possible experience. For this first makes experience possible.”[15]
Before 1792, Kant’s editor commissioned Jakob Sigismund Beck, one of the philosopher’s closest protégés, to write drafts for explanatory essays surrounding the professor’s major works. Through an exchange of correspondence, Beck requested from Kant an explanation regarding specific conceptual ambiguities and contradictions persistent in the first and third Critiques, as well as in a later work: the Metaphysical Foundations of Natural Science. Through said works, what Kant called the Transcendental Deduction disclosed an account of a general systematicity of physics, more technically put forth in the remarks written in the second chapter of the Metaphysical Foundations of Natural Science. However, such postulations offered no indication as to how such systematicity operates. As Kant was aware, they “[provide] no basis for any theory, and [they do] not contain cognition of any objects and their character any more than logic does.”[16] Beck was seeking for a response that would explain certain aspects of mechanics as pertaining to the “Deduction of the Categories and the Principles”, from the Critique of Pure Reason; mainly, Beck enquired into an explanation of the force of gravity in relation to the differences in densities of matter. On September 8, 1972, Beck writes to his teacher: “There is still a question I should like to put to you. It is prompted by your Critique’s extraordinarily illuminating remark that one can think of a space as entirely filled with matter and at the same time postulate an infinite gradation of the real in space. I have never been able to understand the […] differences in weights of the same volume of different substances.”[17] Briefly put, what Beck was tangentially wondering about was Kant’s dynamical theory of matter, which, although epistemologically sophisticated, was lacking a procedural resource that would amend a recursive circularity present in its justification.[18] Consequently, Kant’s theory of matter required a concept that would satisfy both the systematicity of its mechanics and also the transcendental explanation of empirical knowledge of nature. The ether is this concept, one that arises from a principle that would bridge the gap between physics and metaphysics.
Beyond mechanics, beyond the haptics of spacetime, there is a second justification for Kant’s ether: one that is not haptic but optic, or rather, aesthetic. In the Critique of the Power of Judgement, the philosopher articulates a theory of the understanding’s and the imagination’s combined subjective capacity to judge, or what Kant calls taste: to deem something as beautiful. When in the presence of something that is judged as beautiful, an object compels the imaginative and interpretive activity of the faculties free from the intermediation of concepts. “Taste, as subjective power of judgment,” writes Kant, “contains a principle of subsumption, not of intuitions under concepts, but of the faculty of intuitions and representation, under the faculty of concepts, i.e. the understanding, so far as the former in its freedom accords with the latter in its conformity to law.”[19] To perceive something beautiful, at least what Kant means by natural beauty, denotes the underlying proposition that nature features a beauty which perfectly appeals to human taste, as if nature’s forms were made to conform to our sensibility and faculties.[20] Nature’s formal purposiveness—contingent when viewed through a transcendental concept of nature—makes natural beauty appear as if it was designed preadapted to our taste. “So it is actually only in taste,” Kant writes, “more precisely, only in taste concerning objects of nature, that judgment reveals itself as a faculty that has its own principle and hence is justified in claiming a place in the general critique of the higher cognitive faculties—a place one might otherwise not have expected for it.”[21] The capacity of aesthetic judgment, which provides a “universal but yet indeterminate principle of a purposive ordering of nature in a system”,[22] discloses the implication that nature in its entirety is transcendentally systematic. In other words, the systematicity in our taste, in our capacity to judge nature’s forms as beautiful, must correspond with nature’s ulterior purposiveness and systematicity, which, although withdrawn from the unity of experience, can presumably be known through reason. If nature is systematic, we must presume physics to be so as well. “Independent natural beauty reveals [entdeckt] to us a technic of nature that allows us to represent nature as a system in terms of laws,” Kant writes.[23] Accordingly, if one presumes nature’s physis to be systematic, it ought to be an extension of the rational subject’s understanding, and vice versa. Hence the ether serves as the conceptual artifice that conjoins physics and metaphysics into a systematized continuity. On such a systematic basis, Kant’s substance is argued to be the material which fills space, as empty space cannot be experienced.
The fact that no hints of Kant’s ether have been detected in any particle accelerator or quantum physics lab is unfortunate, nevertheless warranted. The curly-headed professor from Königsberg had anticipated that, much like the soul, the world, and God, the ether was beyond any possible experience. In other words, Kant could only postulate the ether implicitly as a thing in itself, as something whose existence is independent from any perception of it. It then follows that the concept of the thing in itself was an epistemological propaedeutic whose logical application disclosed the conceptual basis for the deductions of the ether. Yet the concept of the ether is paradoxical: on the one hand, by virtue of being a concept of transition between physics and metaphysics, it is posited as a material which possibilizes experience; while on the other hand, it is beyond experience, withdrawn from and undetectable to our senses. “Be it called ether, or caloric, or whatever,” writes Kant in the Opus Postumum, “it is no hypothetical material [Materie als einem nicht hypothetischen] (for the purpose of explaining certain phenomena, and more or less obviously conjuring up causes for given effects); rather, it can be recognized, and postulated a priori, as an element [Stück] necessarily belonging to the transition from the metaphysical foundations of natural science to physics.”[24] The ether, being a “primordial motion of matter and the existence of its moving forces must inevitably be postulated, simply because there is motion in cosmic space.” However, because of the a priori nature of the concept, as well as due to the fact that it is nowhere to be found in experience, it follows that the ether cannot reasonably be presumed as a knowable, empirical, nor practical physical substance, material, or quality. Rather, the nature of the ether, regardless of the complexity of its deduction, remains exactly like the thing in itself: a procedural resource, a sophisticated thought experiment, but a thought experiment nonetheless.
The attempt to advocate from a transcendental or otherwise logical standpoint that we share ontological ground with the ether, or with any thing in itself—with God, the soul, or the world beyond its perception—would be to inquire into speculation. This doesn’t imply that such things don’t exist in the conventional sense of the word, just that we will never know through experience, since they are not objects of understanding. By the standards set by Kant in his first Critique, the postulation of the ether—which in the Opus was considered the “transcendental philosophy’s highest standpoint”[25]—seems like an attempt to reintroduce some vitality into the festivity of metaphysics. However, none of the Opus Postumum’s deductions of the ether, with their varying elements and novel formulations, seemed to have left the old Kant completely satisfied.[26] There is no reasonable way to logically proceed and deduce the ether out of its noumenal condition: it remains as the quintessential thing in itself.
Too occupied with the ether and with metaphysical digressions surrounding the completion of his transcendental idealism, his dynamic theory of matter, and his critique of the limits of reason and of judgment, the philosopher overlooked pondering the concept of the thing in itself from the vantage point of a hermeneutic; that is, from the perspective of an action that is employing a conceptual fragment as a resource of interpretation to read into how it fits within its overarching body of knowledge. Although we can’t claim any thing in itself to be present in an ontological sense, we can certainly assure that many different things in themselves exist as narrative artifices that fulfill hermeneutic necessities. In the case of the concept itself—as mentioned above—it was used as a methodological tool with which Kant was able to undertake his philosophical project and illustrate the limits of knowledge that we can acquire through experience. Such explanation for said concept, for how it fits into an overarching systematic, axiological or teleological narrative or model, can be applied to all posited things in themselves: all things which are presumed to be autonomous from any perception of them. For example, the soul serves as an explanation for individuality and free will, as well as a source of solace from death; the world (presumed in itself, as independent from our experience of it) is used as a justification for the endeavors of science, as well as a means and incentive for political action; God is used as the most profound epistemological sediment which is at the bottom of any possible chain of cause-effect relations, and tends to be a datum pertaining to ideals for ethical ways of life. In the case of the ether, it represented an attempt on behalf of the philosopher to resolve gaps left behind in his transcendental system of physics and of metaphysics. Could it be that quantum entities similar to the ether, such as molecules, atoms, and subatomic particles, because of a lack of any possible direct experience of them, are not as ontological as much as they are hermeneutic, in the sense that their only epistemological function is to complete models, establish narratives, and discover cause-effect relations which then posit them as things in themselves? What might a question like this pose for all natural sciences? For the social sciences?
“May God protect us from our friends. From our enemies, we can try to protect ourselves,”[27] wrote Kant in a 1798 letter titled Public explanation regarding Fichte. Previously, Kant had to publicly disclose the fact that—contrary to popular belief—he himself had not been the author of a successful publication titled An Attempt at a Critique of All Revelation. By then, J.G. Fichte, the author of this publication, had increasingly fallen out of Kant’s favor. Kant vehemently disapproved of Fichte’s philosophy. One of the reasons Kant might have developed (around the same years he was working on the Opus) such hostility towards Fichte might be because the former protégé, in his own philosophical system—called the Science of Knowledge [Wissenschaftslehre]—partly elaborated beyond epistemological accounts of the thing in itself and offered a hermeneutic interpretation of the concept. Fichte reasonably argued that, since nothing which is out of our intuition, understanding or perception can ever be experienced, the claim that any thing exists in itself—as independent of any interaction with it—is an argument that derives from dogmatism. Since something in itself cannot be an object of experience nor of knowledge, the postulation of such a thing would not be motivated by empirical arguments, but by metaphysical prejudices seeking to be hypostatized, aspiring universal validity. In the First Introduction to the Science of Knowledge, Fichte writes, “The thing-in-itself, which is the fundamental principle of the dogmatist, is nothing and has no reality, as even its exponents must concede, apart from what it is alleged to acquire through the circumstance that experience can be explained only on its basis […] [T]here no longer appears to be any reason at all to assume [a thing-in-itself]; and with this the entire edifice of dogmatism collapses.”[28]
What does this mean for the ether? Since Kant posited it as a hypothetical material which is in itself the condition of possibility for experience, this would imply that no transition between physics and metaphysics is possible. And so, it is not tenable to reasonably speculate on the nature of metaphysics as derived from the perceived order of physics—of physis, of what appears to our experience and the laws that govern it. The fact that these conclusions are reached by means of the critical postulations from the same author who would later attempt to overcome them, discloses how, by writing the Opus Postumum, Immanuel Kant became the first post-Kantian. This might be one of the reasons his figure continues to loom over philosophy as we know it.[29] After motivating a revolution in the history of thought, Kant possibly knew that just because no transition between physics and metaphysics is possible does not mean one cannot try. In other words, the old Kant—refusing to lay down the pen—was unwilling to miss out on the party that is metaphysical speculation. Those of us involved with the philosophical task might either enjoy or pity ourselves for recurringly going along.
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[1.] For readers who may not be familiar with Kant, it might help to know that throughout his Critiques, the word transcendental is a technical term. Briefly stated, it refers to what is required for knowledge to be attained through experience. Eckart Förster offers this clear explanation: “All empirical truth, that is, all experience, involves change. As such it requires something “permanent in perception” in relation to which the alterations can be determined.” Such permanence is that which is transcendental, and is usually also referred to as the a priori condition for knowledge.
[2.] Immanuel Kant, The Critique of Pure Reason (Kritik der reinen Vernunft [form now on cited as Krv]), Paul Guyer, Allen W. Wood [ed. & trans.] (Cambridge University Press, I998), 362 [B311]. “The concept of a noumenon is therefore merely a boundary concept, in order to limit the pretension of sensibility, and therefore only of negative use. But it is nevertheless not invented arbitrarily, but is rather connected with the limitation of sensibility, yet without being able to posit anything positive outside of the domain of the latter.”
[3.] Although there might be commentators that insist on a metaphysical reading of Kant, this essay’s point of departure is the fact that Kant leaves no necessity for transcendental objects nor things-in-themselves to exist ontologically, only epistemologically. Kant puts forth this case throughout On the ground of the distinction of all objects in general into phenomena and noumena, the third chapter of The Transcendental Doctrine of the Power of Judgment (Analytic of Principles) [A235/B294-A260/B315] in the Critique of Pure Reason, and also in §52, §52B and §52C of the Prolegomena to Any Future Metaphysics. Kant, KrV [A260], in The Critique of Pure Reason (Cambridge University Press, I998), 365: “Thus the concept of pure, merely intelligible objects [like any thing-in-itself] is entirely devoid of all principles of its application, since one cannot think up any way in which they could be given, and the problematic thought, which leaves a place open for them, only serves, like an empty space, to limit the empirical principles, with-out containing and displaying any other object of cognition beyond the sphere of the latter.”
[4.] Kant, KrV [A255/B310], in The Critique of Pure Reason (Cambridge University Press, I998), 362: “I call a concept problematic [problematisch] that contains no contradiction but that is also, as a boundary for given concepts, connected with other cognitions, the objective reality of which can in no way be cognized. The concept of a noumenon, i.e., of a thing that is not to be thought of as an object of the senses but rather as a thing in itself (solely through a pure understanding), is not at all contradictory; for one cannot assert of sensibility that it is the only possible kind of intuition. Further, this concept is necessary in order not to extend sensible intuition to things in themselves, and thus to limit the objective validity of sensible cognition (for the other things, to which sensibility does not reach, are called noumena just in order to indicate that those cognitions cannot extend their domain to everything that the understanding thinks). In the end, however, we have no insight into the possibility of such noumena, and the domain outside of the sphere of appearances is empty (for us), i.e., we have an understanding that extends farther than sensibility problematically, but no intuition, indeed not even the concept of a possible intuition, through which objects outside of the field of sensibility could be given, and about which the understanding could be employed assertorically.”
[5.] KrV [A256/B312], in The Critique of Pure Reason, 363: “Nevertheless the concept of a noumenon [of the thing in itself], taken merely problematically, remains not only admissible, but even unavoidable, as a concept setting limits to sensibility. But in that case it is not a special intelligible object for our understanding; rather an understanding to which it would belong is itself a problem, that, namely, of cognizing its object not discursively through categories but intuitively in a non-sensible intuition, the possibility of which we cannot in the least represent.”
[6.] Problematic in the sense that is alluded to in the 3rd footnote.
[7.] For example, within the First Edition (1781), the passages from the Fourth Paralogism of the Ideality [A367-A380] regarding the thing-in-itself were later undermined by the Refutation of idealism [B274-B279] from the Second Edition (1789).
[8.] See editor’s introduction to Immanuel Kant, Opus Postumum, Eckart Förster [ed. & trans.] (Cambridge University Press, I993), xvi-vliv.
[9.] Mainly, the fact that the thing in itself was required for Kant’s theory of sensibility while simultaneously being negated by his theory of the understanding. Otto Liebmann suggested that while the Transcendental Aesthetic and Analytic posit that the intellect cannot know beyond empirical phenomena through the form of sensibility and the understanding’s logical categories’ functions, Kant nonetheless looks condescendingly at Leibniz and Wolff’s metaphysics for recognizing objects free from the forms of understanding.
[10.] Burkhard Tuschling, “Apperception and Ether: On the Idea of a Transcendental Deduction of Matter in Kant’s Opus Postumum” in Kant’s Transcendental Deductions ed. Eckart Förster (Stanford University Press, 1989), 207.
[11.] The scope of this essay pertains to fascicles II, X and XI in the Opus Postumum, especially the section titled Ether Proofs, and within it, particularly the section Übergang 1-14. Some pages from the latter section have still to be translated to English and were consulted in the secondary literature.
[12.] Immanuel Kant, Opus Postumum [from now on cited as OP] ed. & trans. Eckart Förster (Cambridge University Press, 1993), 21:209-10. Translated quote from Burkhard Tuschling, “Apperception and Ether: On the Idea of a Transcendental Deduction of Matter in Kant’s Opus Postumum” in Kant’s Transcendental Deductions ed. Eckart Förster, (Stanford University Press, 1989), 202.
[13.] OP, 21:593. Quote and translation from Paul Guyer, “Kant’s Ether Deduction and the Possibility of Experience” in Kant’s System of Nature and Freedom (Oxford University Press, 2005), 74.
[14.] OP, 21:224. From Paul Guyer, Kant’s Ether Deduction…, p. 79.
[15.] OP, 21:550. From Paul Guyer, Kant’s Ether Deduction…, p.74.
[16.] Immanuel Kant, First introduction in Critique of Judgment trans. Werner S. Pluhar (Indianapolis: Hackett, 1987).
[17.] J.S. Beck, “September 8, 1792”, in Immanuel Kant, Correspondence, Arnulf Zweig [ed. & trans.] (Cambridge University Press, I993), 427.
[18.] See Eckart Förster, “The ‘Green Color of a Lawn’ And Kant’s Theory of Matter” in Kant’s Final Synthesis: An Essay on The Opus Postumum (Cambridge: Harvard University Press, 2000) 24-47.
[19.] Immanuel Kant, Critique of Judgment trans. James Meredith (Oxford: Oxford University Press, 1952); from Eckart Förster, Kant’s Final Synthesis: An Essay on The Opus Postumum (Cambridge: Harvard University Press, 2000), 9.
[20.] See Eckart Förster, “The Idea of a Transition” in Kant’s Final Synthesis, 1-11.
[21.] Immanuel Kant, First introduction in Critique of Judgment. From Eckart Förster, Kant’s Final Synthesis, 10.
[22.] Ibid., 11.
[23.] Immanuel Kant, Critique of Practical Reason trans. Lewis White Beck (Indianapolis: Bobbs-Merrill, 1956). From Eckart Förster (2000), 8.
[24.] OP, 69 (21:218).
[25.] Ibid., 235 (21:32).
[26.] Eckart Förster. “Ether Proof and Selbstsetzungslehre” in Kant’s Final Synthesis, 82-101.
[27.] Kant goes on to write, “For there may be also fraudulent and perfidious friends who are scheming for our ruin, although they speak the language of benevolence one cannot be sufficiently cautious in order to avoid the traps they set for us.” He was talking about Fichte, of whom he also declared that, in his view, “Fichte’s system was totally untenable”. At a different time, he declined being in any way involved with a philosophy which consisted of ‘barren subtleties’. See Karl Popper, The Open Society and ats Enemies Vol.II The High Tide of Prophecy: Hegel, Marx, and the Aftermath (London: Routledge, 1947), 52 (footnote 58 [p. 298]).
[28.] J. G. Fichte, “First Introduction to the Science of Knowledge” in The Science of Knowledge eds. & trans. Peter Heath and John Lachs (Cambridge University Press, 1982), 13 (I, 431).
[29.] Cf. Catherine Malabou, “Can We Relinquish the Transcendental?” In The Journal of Speculative Philosophy Vol. 28, No. 3 (Penn State University Press: 2014): 242-255.