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Accessible Published by De Gruyter December 27, 2019

Lotze’s Debt to Kant Against Naturalism and Czolbe’s Counterpoint. The Ambiguities of “Epistemological Kantianism” Around 1850

Charlotte Morel ORCID logo


The decline of Naturphilosophie deeply polarized the philosophical and scientific debate. Naturalistic–materialistic positions gained powerful influence, but the latent role of the Kantian critical position also re-emerged in the context of an “ideal-realism”. I will first consider in detail two opposing treatments of Kant’s perspective. After Lotze had criticized his earlier materialistic position, advising him to read Kant, Czolbe finally addressed Kant, thereby progressing to a non-materialistic form of naturalism. However, whether to defend or to dismiss naturalism, neither philosopher addresses Kant as a transcendentalist thinker, and I go on to examine this common feature in their writings. This invites us to reconsider what exactly in Kant’s system conflicts with naturalism. Is transcendentalism too broad a requisite for that task? Within “ideal-realism”, the realist part actually implies a denial of transcendental idealism; still, it shows how a realism which refuses to be naturalism could well learn from Kant.

Around 1850, many philosophers and scientists in Germany reacted against what they called, at best, the “excesses” of Naturphilosophie. In particular, some thinkers detached the label of “ideal-realism” from its Fichtean-Schellingian origin; they claimed that philosophy and natural science should be reconnected on a totally different basis, accepting their methodological discrepancy.[1] Such refusal of any speculative connection of the ideal and the empirical was likely to give rise to a new exploitation of the Kantian critical position. This perspective is well thematized in the second volume of Friedrich Albert Lange’s milestone work, History of Materialism and Criticism of its Present Importance: History of Materialism since Kant (Lange 1875).[2] Building on Lange’s analysis, Klaus-Christian Köhnke, in his masterful study of the various Kantian trends developing throughout the nineteenth century, clearly identifies the controversial impact of materialism as one of the factors at stake.[3]

Because philosophy in the 1850s and 1860s had to overcome the idealism of the past as well as the materialism of the present, it was able to develop a rather acute sense of the way Kant had striven to build bridges between a priori and a posteriori knowledge. (Köhnke 1993, pp. 175f.)

Indeed, at that time, naturalistic–materialistic positions had become a very influential trend. After 1854, not only the German intelligentsia but society as a whole was involved in the so-called “materialism controversy” and experienced the tremendous influence of works by Ludwig Büchner, Carl Vogt and Jacob Moleschott.[4]Force and Matter by Büchner was a huge editorial success throughout Europe, whilst Vogt and Moleschott had comparable influence in Germany. One of the characteristics of these works was their popular style which earned them the epithet “popular materialism”, and enabled them to appeal to a wide audience beyond academic circles. A second characteristic was well summarized by Kurt Bayertz with the label “scientific materialism” (see Bayertz 2007): whilst eighteenth-century philosophers propounded as a metaphysical assertion that the whole world could be explained by studying its physical components, nineteenth-century thinkers instead interpreted this stance as a consequence of unlimited confidence in the explanatory powers of natural science.[5]

In this context, what did “being Kantian” signify, and why be one? It is quite well known nowadays how a first option resulted in a position which seems in itself a paradox, not to say a heresy, as seen through the very eyes of those whom we now name Neo-Kantians (i. e., the Bade and Marburg school): “naturalizing the transcendental” i. e., connecting Kant’s theory of critical idealism with empirical physiology and psychology. From different perspectives, this was the stance either of philosophers such as Lange himself, or Jürgen Bona Mayer (“‘the last great hurrah’ of the psychological interpretation of Kant” following Jakob Fries’ interpretation, in the words of Beiser 2014b, p. 336); or of prominent scientists such as Rudolf Virchow (physician and anatomist), Hermann von Helmholtz (physicist and physiologist).[6]

But appeals to Kant soon also represented a very strong means to oppose the naturalistic–materialistic positions[7] by pointing out an oversimplification of epistemological issues. This paper will focus on the example of Lotze. Though the way Lotze addressed Kant’s main orientations is to be carefully evaluated as a mix between premises he built on and premises he denied in the perspective of his own “ideal-realism”,[8] we can observe this reference to Kant as a strategy – among others – in his rebuttal of Heinrich Czolbe’s sensualistic and naturalistic approach to consciousness.[9] Not only are Czolbe’s and Lotze’s views in direct conflict as naturalistic and anti-naturalistic (the following paragraphs will set forth this opposition in more detail, expanding on the preliminary remark in my previous footnote), but they have both specific characteristics that seem to me worthy of further discussion, as will be shown below.

On this basis, my paper will first consist in evaluating the role of Kant’s work for both of them. But this inquiry is not a solely historical one. Historical knowledge is rather, in this case, conceived of as helping us formulate what I hope to be useful questions and distinctions about the following point: what exactly within the “transcendental claims”, taken as a whole, is in a position to offer a logical theoretical objection to the premises of strict or broad naturalism, and how?[10] This will lead me to question in particular the issue of whether appealing to Kant in this context amounts or not to appealing to transcendental claims whatever they are.

1 Lotze’s Kantian Background in Physiology and Psychology

Czolbe was a physician in Königsberg, he had Feuerbach as a “mentor” (Gregory 1977, p. 141), and seemed to have played the same role to the ideal-realist philosopher Friedrich Überweg, his friend and patient, and also philosophy professor at the Königsberg university from 1862.[11]

As for Lotze, he is one of the most significant figures of this ideal-realist stance in the mid-nineteenth century.[12] His work had a major impact on many prominent thinkers of the next two generations and indeed thinkers as different as Stumpf, Windelband, Rickert, Dilthey, Frege, Husserl on the German side, but also Royce, Bosanquet, MacTaggart, James and Russell on the English-American side. In most of these cases though, it was the works of the second period of his lifetime that proved to be decisive for Lotze’s legacy: his 1874Logic, his 1879 Metaphysic (Royce, Bosanquet, McTaggart) and his three-volumed Microcosmus, an “essay concerning man and his relation to the world”.[13] But Lotze also had another side. He was trained both as a physician and a philosopher and his first writings in the field of medical and natural science[14] aroused interest amongst such wide and heterogeneous circles of theoricians that he was hailed as a natural arbiter in the materialism controversy, being taken to task by both sides. However, he managed to firmly decline this role, making clear to materialists that his advocating unambiguously in favor of the integral mechanism as a strict methodological requisite for the rigorous practice of natural science (the investigation of empirical phenomena) could in no case be interpreted as being conducive to materialists views. Yet Czolbe did just that.[15]

To Lotze, the materialism of his time was a “naturalistic metaphysics”. And this he comments on negatively as a one of those positions “which luxuriously proliferates wherever people believe they have freed themselves from all metaphysics, and to be standing firm upon the soil of experience and natural-scientific intuition” (Lotze 1852, § 3, p. 32). Leading authors of the popular materialism of his time had no sense of the distinction between methodological and ontological naturalism, primarily because they had no interest in epistemological topics but advocated materialism first as a world view – with little logical scrutiny. Today, however, now that naturalism has been promoted to a prevalent position within twentieth-century epistemology, this is no longer true; this distinction between methodological and ontological naturalism has been made explicit through the careful subdivision of naturalism and even “scientific naturalism” into different versions, with ontological naturalism being based, for instance, mainly upon the causal closure of the physical realm.[16] And from a methodological perspective, if we rely this time on the distinction between “strict” and “broad” naturalisms[17]: the definition of materialism as equated to naturalism provided by Wagener in 1863 (and indeed matching the popular materialism contention), to which we have already referred above in footnote 7, allows us to conclude that this corresponds with our meaning of “strict naturalism”.

I summarized Lotze’s overall response to the materialistic naturalization of psychology[18] in an online paper (Open Access: Philosophical readings); here I would like to discuss the function of some “Kantian” elements within this global framework.

In his formative years, Lotze had undertaken a very close reading of Kant, including his Metaphysische Anfangsgründe der Naturwissenschaft, as well as of Fries’ works.[19] This is evidenced in his correspondence with a friend from his youth, Ernst Friedrich Apelt. Although Lotze objected to Kant’s and Fries’ dynamism in physics,[20] his early epistemological writings are evidence that he took a close interest in some of Kant’s other philosophical claims. It is important to note from the outset that this Kantian background is both explicit (any reader familiar with Kantian philosophy cannot fail to recognize it), and inexplicit (that is: Lotze makes no direct reference to Kant’s works and very few to Kant’s concepts in Kants wording).

Here is an example from Lotze’s theory of biology in his essay “Leben. Lebenskraft” from 1842.[21] While Lotze’s contention about teleology in nature is primarily related to Leibniz on the metaphysical level, here he nonetheless makes a move towards a Kantian methodology describing the “application of teleology” to vital phenomena as a “heuristic maxim”; and then he comments on this point, underlining the difference between judging upon facts and judging about purposes, as the first and the third of Kant’s Critics taught us to do:

Whilst universal laws can be understood a priori, and real facts and relationships can readily be observed and experimented upon, the purposes of nature are in no way directly given to us, and mostly they can only be derived by drawing a common analogy from phenomena themselves. (Lotze 1885b, p. 151)

Although it may seem quite contradictory to us, both of these orientations are indeed a characteristic feature in Lotze’s approach to the knowledge of nature.

As for psychology, Frederick Beiser pointed out what Lotze retained from Kant,[22] although in this field as well, Lotze’s overall orientations rely on many different perspectives too.[23]

Czolbe had first published a reply to Immanuel Fichte’s critique of materialism,[24] the same year as Force and Matter. It proved an important contribution, siding with materialists, even if, as the title indicates and the author still later elucidates,[25] Czolbe employed the label sensualism rather than materialism to define the way he commits himself to naturalism. And indeed, he uses this term too, advocating more exactly a “cleansed naturalism” (Czolbe 1855a, p. 33).[26] This he understands, theoretically at least, as a demand for a pure, mechanical explanation of the world order.[27]

Lotze’s first concern with Czolbe is to counter his radical empiricism in dealing with psychic activities. As Beiser summarizes, he proceeds here on the methodological level: “Lotze’s argument is basically a restatement of Kant’s famous reply to Hume, a timely reminder for materialists of a basic philosophical point: that the universal and necessary connections of our most fundamental concepts cannot be derived from experience” (Beiser 2014a, p. 86).[28]

Here are Czolbe’s words quoted by Lotze:

It would seem that it is only possible to attain a clear intuition of this unity of all experiences if the activities which constitute these experiences are inherently self-reflexive, referring back to themselves. (Lotze 1855, p. 243)[29]

Then comes Lotze’s point: when evoking unity in consciousness in these terms, the Königsberger physician may not be aware that he makes use of a “spatial metaphor” or, as Lotze puts it, “a spatial symbolization”; and quite contrary to Czolbe’s claim, Lotze criticizes this metaphor for being “unclear” (unanschaulich), – a frontal attack, since it targets his opponent’s principal philosophical criterion (above our footnote 27 and the “main principle of sensualism”). Materialists or sensualists such as Czolbe can be asked a very simple question: what exactly is making this “move”, “referring back to itself”? Lotze too uses metaphors, as a matter of fact he broadens his opponent’s metaphor to demonstrate the argumentative limitation of this spatial imaginarization of conscious acts: “Shall we credit a potter’s wheel or a coach’s wheel with consciousness as long as they rotate, or an electric current as soon as it forms a closed circuit?” (Lotze 1855, p. 243). Assuming that a spatial metaphor brings “clarity” in such issues means confusing the two distinct meanings of the German term “anschaulich” used by Czolbe on behalf on his sensualist premises: comparing something to an intuition-based process does not always make it clear.

And Lotze remains a logician first and foremost, which is why he asks about the “subject” to which the “predicate” “referring back to itself” refers (Lotze 1855, p. 243).[30]

But then comes the main difficulty. And Lotze’s response to it is, without using the term, Kant’s transcendental apperception.

Besides, the author confuses two different issues one with another. First he predicates consciousness, i. e., referring back to itself, from every single psychic activity; yet his deduction could only prove how every single brain process achieves consciousness of itself; but not at all how it reaches our consciousness, that of the unique “I”:

that is the “unity of all experiences” (Lotze 1855, p. 243).[31]

Indeed, Lotze at least once used Kant’s technical expression: “transcendental unity of perceptions”. But it was in his very first theoretical text, the medical dissertation from 1838… hence in Latin wording: “This transcendental unity of perceptions is not a category of natural philosophy but belongs to an entirely different series of notions”.[32] Although not further developed, this statement by the young Lotze at least makes it clear that Kant’s transcendentalism was originally a relevant inspiration for his objection to naturalism.

As for his objections to Czolbe, Lotze’s claim is made very clear in its in conclusion.

This is the old issue of how unity of consciousness is possible, and here the author totally forgot about it. But one thing is certain: until materialism considers this very fact, it cannot hope to persuade us that it is in a position to rebut its opponents. (Lotze 1855, p. 244)

So, to counter the sensualist version of naturalism, it is a certain kind of transcendental justification that is at stake here. As regards consciousness, you do not explain what needs explaining unless you make sure the possibility of an experience is indeed accounted for. To this extent, the phenomenon of consciousness was the only one that could enable Lotze to formulate his demand, because consciousness actually consists in the phenomenon of experiencing something. This transcendental condition regarding the unity of consciousness is what Kant named transcendental apperception. And if this answer to the problem were to be accepted, since this latter category pertains to “an entirely different series of notions” from that used by “natural philosophy” (to borrow Lotze’s wording from his 1838 dissertation), it would indeed mean that we would have ceased to expect anything resembling a materialistic explanation.

For Lotze, querying the essence of consciousness is also a way of stressing the difference – for him an unbridgeable one – between external and inner phenomena: only the latter being experienced. And I think this too engages reflexivity – this time in a way that does not primarily stress the category of unity, but that of quality. In other words, the only true “reflexivity” cannot exist on the level of external phenomena, those which are accounted for through determining their relationships in space and time – that is to say, via a quantitative analysis (typically, Czolbe only takes movement into account); instead experiencing a phenomenon means that a shift has been made from a quantitative to a qualitative dimension. Only an appeal to the logical incommensurability of quality and quantity can highlight the unity of consciousness as a condition of experience in general.

Lotze’s argumentation against Czolbe is that of a logician: these “entirely different series of notions” which depart from the “categories of natural philosophy” are indeed logical categories. But then here I have to raise the following question: since

  1. (1)

    Lotze is behaving here as a logician;

  2. (2)

    So as to remind his reader of the necessity of “transcendental apperception” to counter crude simplifications in the way materialists try to make their psychological point:

  3. (3)

    Then should we merge both these assertions to draw the following conclusion: must the logic to which he is appealing be, in turn, a transcendental logic? (That is, a logic that encompasses the subject’s pure contribution to the constitution of knowledge, insofar as the content (« Inhalt ») of representations ultimately depends on the « form » given by the acts in the subject).[33]

This question immediately takes on the proportions of a problem and leads us to point out a twofold stance in Lotze’s logic. Acts of thought are indeed required to form logical ideas such as relationships of equality or inequality (as they are required to form sensory representations).[34] But insofar as logic strives to a “real” (or in some cases “material”) and not merely “formal significance”, it has to distinguish between such acts and their “result”[35]: “logical operations […] are merely forms of procedure, employed to reach a certain result which once obtained is valid independently of the path which led to it” (Lotze 1884a, p. 493; my underlining). In other words, the content of our representations genetically “results from” acts of thought, or rather, acts of thought “result in” contents of representation, but once reached, this content no longer “adheres” to the act itself. The finality of logic is to reach such independent contents of thought, and thereby an objective and material significance – “which does not belong to the thinking act which issues in it” (Lotze 1884a, p. 493). In other words again, as soon as logic enters the regimen of validity, it also goes beyond the transcendental regimen where the resulting “thought” (Gedanke) does not separate from the act of thinking.[36]

This is important to our present inquiry since I assume, then, this is the reason:

  1. why Lotze avoids any direct use of Kantian vocabulary even when making points that refer to a Kantian background

  2. from which we should infer the correct understanding of how Lotze did make use of Kant against naturalism, although his own approach also goes beyond transcendental logic.

2 Two Opposite Ways of Appealing to Kant to Address Naturalism: Lotze and the “Second” Czolbe

2.1 Czolbe 1865: Using Kant for an Anti-materialistic Naturalism?

Firstly, I shall return to Czolbe: despite Lotze and Czolbe’s opposing stances on naturalism, we find a common feature in their consideration of Kant – that is, to learn from his approach of ideality without endorsing the transcendentalist claim.

Mostly as a result of Lotze’s severe critique in 1856, Czolbe engaged in a substantial revision of his philosophical claims; in his second book in 1865, he both deals with Kant’s work and rejects what he labels Kant’s “subjectivism”,[37] as an answer to those who, at that time, turned to Kant’s critical idealism as a form of “skepticism” (in the first place Jürgen Bona Mayer).[38]

Then what is the nature of Czolbe’s “way out” of that which he refers to as the “Kant–Hegel problem” – i. e., the search for a coincidence between subjective and objective in knowledge? Indeed, it is a still naturalist one. In his second book, Czolbe proved he had listened to what Lotze and others had to say,[39] and had studied Kant; as a result, he retracted his former materialist stance and turned to a non-materialistic form of naturalism.

Rokitanski advises [the materialists] to study Kant and to understand from a Kantian perspective the problems that remain to be solved. This advice I have followed with much pleasure and conviction, and the result of the speculations this has led me to [is] the solution of the Kant-Hegel problem, from a naturalistic perspective, and the definitive refutation of materialism – as substantially different from naturalism […]. (Czolbe 1865, viii)[40]

As I consequence of which I wish I could ask Czolbe the following question: Why should Kant’s “problem” be compatible with naturalism, rather than with materialism? Are transcendental claims at stake here? At the very least, this issue questions the relationships between transcendentalist and naturalistic claims.

We find interesting comments on this question in the essay that Hans Vaihinger, himself a future Neo-Kantian, devoted to “the three phases of Czolbe’s naturalism” in 1876.

It is not the power of natural scientific facts or the concept of philosophy itself (which logically excludes the incomprehensible because it wants to comprehend everything) that leads to the exclusion of all supersensory elements, as [Czolbe] thought in his first period, but on the most fundamental level, morality […]. This new development is enlightening; it clearly shows that by plunging deeper into the history of philosophy, Czolbe had gained insight into the logical possibility of another method and started doubting whether everything could really be reduced to perceptible (anschaulich) representations and purely mechanical processes […] Obviously Kant had had an impact on Czolbe […]. (Vaihinger 1876, pp. 17f.)

From Kant, Czolbe learnt to distinguish a methodological and an ontological level in the problem he was dealing with. So in his new phase, he still stuck to the rejection of the “supersensory”, but only on the methodological level: ontologically, he now recognized a “soul” (more exactly a “world soul”) as a second element in the world, alongside material “atoms”. This was a step out of materialism; yet in Czolbe’s comprehension he remained within the limits of naturalism: as in the ancient stoicism, these elements distinct from matter are still included in nature (physis).[41]

From today’s perspective we would perhaps include this position within the bounds of broad naturalism; Czolbe claimed to be reconciling the Kantian premises with this broader understanding of naturalism: even the non-sensory elements of reality are part of nature. Of course, it is also impossible to state that Czolbe’s views here are, indeed, Kantian ones … and Czolbe himself is clear about still opposing Kant’s “things in themselves”, for instance.[42]

So, as I aimed to establish here: although their conclusions regarding naturalism are in radical opposition, both Czolbe and Lotze testify that one can use Kant’s critical impulsion without endorsing a transcendental point of view in one’s personal system.[43]

2.2 A Priori Without Transcendental Logic: The Lotzean Argument Against Naturalism

My last point sets out to show how Lotze addressed Kant in an opposite way, that is, against naturalism, notwithstanding his only feature in common with Czolbe’s approach to Kant: non-transcendentalist claims. But why appeal to Kant without any reference to transcendentalism? Obviously, referring to Kant in this way is something we unlearned due to the greater influence of “classical” Neo-Kantianism from Marburg and Bade whose revival of Kant is, in the first place, a revival of transcendental philosophy.

Kant’s transcendental point of view in philosophy implies, on the one hand, ontological realism as regards the existence of empirical beings as such, independent from the mind (his “refutation of idealism”); and on the other hand, epistemic idealism as regards our knowledge of these beings as objects. In this criticist version of idealism, the very constitution of objectivity in knowledge implies the effectivity of subjective acts; in principle, this undermines the relevance of the question “what are things in themselves?”. A priority is the basis for objectivity, but as the logical frame of the human mind: thus, we have a transcendental logic on which to base a transcendental system of knowledge.

Yet, since Herbart, being a “realist” means more than ontological realism; it implies epistemic realism as well. The human mind is not confined to phenomena; or more exactly, its phenomenal knowledge also provides it with knowledge of what things are. What realism objects to, in principle, is the transcendental idea of an unbridgeable gap between phenomena and “real being”. Herbart developed this idea thanks to the linking of mathematics with metaphysics. As for “scientific” ideal-realism, the option was a different one: with, so to say, the task-sharing between natural science (empirical epistemic realism) and metaphysics (ontological idealism in the sense of an overall teleological spiritualism) on the presupposition that: (a) each of them has its own methodological jurisdiction but (b) they are also connected insofar as the latter is the ultimate basis for the validity of the former.

Within the global frame of this dual system of ideal-realism, and here namely as a realist, Lotze objects to any form of radical epistemic subjectivism. His claim is radical, since he objects in principle to contrasting a “world of representations” and a “world of things” (Lotze 1989b, ch. 1, § 312, p. 504.[44] A key concept in his Logic is, instead, that of a “world of the thinkable (Denkbare)” (Lotze 1989b/1974, in particular: ch. 2, § 318)[45] – whose elements are “conceptions having […] their own fixed and unchanging meaning” (Lotze 1884a, part III, ch. 3, § 313, trad. Bosanquet mod., p. 434), and their relationships. That is, the “content” which the logician must single out from amongst all of our representations, as its “objective” part, in contrast with its “subjective part”, “affection” (Lotze 1884a, part III, ch. 2, § 314, p. 435)[46]; such ideal content “continues to be what it is and to mean what it means whether we are conscious of it or not” (Lotze 1884a, part I, ch. 1, § 2, p. 11),[47] which then also implies that transcendental logic has been superseded. This is Lotze’s theoretical breakthrough, that will mean so much to Frege and young Husserl – not to mention others. In identifying an inner content within our representations that holds true (gilt) independently of “the thinking act which issues in it” (Lotze 1884a, p. 493), Lotze gives a key role to the a priori in a post-transcendental way.

It is well known that Lotze put forward a new reading of Plato’s “Ideas” to set up these conceptions (Lotze 1989b/1874 and 1884a, part III, ch. 2 as a whole: “Die Ideenwelt”). But Kant is never far away: we just have to take a close look at the whole of Lotze’s third book in the Logic.[48] And there is a connection with our investigation: what Lotze presents us with there is how a realism which refuses to be naturalism could well learn from Kant.

Commenting on the context of Lotze’s “World of Ideas” chapter in Logic, the Husserl scholar Françoise Dastur pointed out how this section directly builds on one of Lotze’s anti-Kantian statements about the way to dismiss skepticism (cf. Lotze 1989b, ch. 1, § 312; Dastur 1994, pp. 41f.). Could we respond to skepticism by distinguishing between “appearances” and the “essence” of things? According to Lotze, this would leave us only with default knowledge – meaning that we would do better to object to this very distinction “between our world of ideas (Vorstellungswelt) and a world of things” (Lotze 1884a, III, ch. 1, § 312, pp. 431f.). There is now room for Plato’s re-reading. Yet we should not read Lotze’s chapter 2 about Plato without then reading chapter 3 about “a priorism and empiricism”. Kant is not dismissed by Plato: he reappears after the “Platonic” second chapter with a very significant function regarding what has been gained in the first step. For what is at stake is the issue of natural science and its philosophical foundation in logic.

In § 320, Lotze addresses not only “ideas” but also “laws”: and it still remains to him “a profoundly mysterious fact” (“ein Abgrund von Wunderbarkeit”) “that there should be universal laws, which have not themselves existence like things and which nevertheless rule the operations of things” (Lotze 1884a, III, ch. 3, § 320, p. 520, p. 446. My underlining). According to the last paragraph of chapter 2, Plato failed in one thing: Plato’s ideas logically present themselves in the form of concepts and not of judgements. But such are laws, which “rule the operations of things” on the phenomenal level and constitute as such the operator of scientific knowledge of things for human reason. There we find Kant back: he too “made the mistake at the outset of developing [the a priori] form of single concepts, the categories” (Lotze 1884a, III, ch. 3, § 321, p. 448; Lotze 1989b, pp. 521f.); but at least,

thereupon [he] followed up with the attempt to derive judgments from them again, and so he arrived at the ‘Principles of Understanding’. (Lotze 1884a, p. 448)

In chapter 5, “The A Priori Truths”, Lotze is definitely clear about the ultimate use of these “contents” that were gained as “ideal” ones: the inner structure of the “world of thought”, as pure thought, “is not all that we desire to know” (this would be the Platonic Dialectic);

What we want to understand is the significance which is to be attached to this systematic* arrangement of the world of knowledge in relation to that empirical* and unsystematic order of events, in which a causal reality independent of thought presents contents of possible ideas to our perception. What we wish to understand is not only the classification* of things, which is eternal, but also the course* of things which is in movement. (Lotze 1884a, III, ch. 5, § 346, mod. transl., p. 497)[49]

I assume that this corresponds to our knowledge of the natural world.[50] For Lotze, apriorism in the meaning of concepts and laws is the logical requirement for founding natural science, thus avoiding naturalisms lack of logical consistency. This aprioristic claim is clearly of Kantian origin but, thanks to its Platonic “re-elaboration”, it eventually reaches beyond the transcendentalist claim.

3 Conclusion

Contrary to the position of the Marburg and Bade schools, to Lotze’s view it is not the transcendentalist claim that proves to be the convenient perspective in order to counter naturalism. And from this a significant consequence is to be derived: there is no more risk of “naturalizing the transcendental”, as in Helmholtz’s or Lange’s approach to Neo-Kantianism. Consequently, this broad reading of both Lotze and Czolbe invites us, as was my purpose, to reconsider what exactly in Kant’s system is conflicting with naturalism.

For Lotze, a first answer could have been the identification of the ideal thought frame with a teleological structure. But in Czolbe’s writings, this is not relevant anymore: Czolbe too accepts teleological structures, whilst at the same time siding with naturalism.[51]

Then we may stress the role of logic in natural science. Lotze’s non-naturalistic understanding of the validity of science is based upon the central role assigned to logic to that purpose. By contrast, Czolbe’s naturalism (among others) takes no interest in a logical perspective. That is also the reason why what is at stake here is not ontological, but methodological naturalism – the latter being dismissed by Lotze on the basis of a priori claims.

In Lotze’s case, the distinctions pointed out by Joel Smith and Peter Sullivan as regards “transcendental idealism” and “transcendental arguments” seem effective (2011, pp. 2–5). In particular, if we adopt Kant’s own elucidation of what a “transcendental philosophy is”, there is no objection to classifying Lotze in this group: “I call all cognition transcendental that is occupied not so much with objects but rather with our mode of cognition of these objects insofar as this is possible a priori. A system of such concepts would be called transcendental philosophy” (Kant 1787, introduction, VII, AA III, 43). As a matter of fact, this does not necessarily imply the claim of transcendental idealism as “the doctrine that [appearances] are altogether to be regarded as mere representations and not things in themselves” (Kant 1781, “Kritik des vierten Paralogismus der transcendentalen Psychologie”, AA IV, 232). And indeed, as we saw, this is a claim that Lotze does not accept. Within the set of Kant’s philosophical claims, Lotze singles out apriorism as the specific and central element suited to dismiss naturalism – and ultimately this can prove independent from transcendental idealism or transcendental logic.

This reading of nineteenth-century writers who took a stand on naturalism allows me to conclude with the following remarks:

  1. (1)

    The contemporary labels distinguishing different forms of naturalism prove to be relevant for this prior period in the history of the problem, just as they were in the context in which they were coined. The second version of Czolbe’s naturalistic system is a “broad naturalism”, which sharply contrasts with the scientific materialism at stake with Büchner, Vogt and Moleschott a decade earlier: this latter matching, on the contrary, the features defining a “strict naturalism”.

  2. (2)

    As regards the respective positions of naturalism and transcendental claims, I think this historical inquiry allows us to expand our understanding of the contemporary issue. Since our authors refer to Kant in some respects but not to his general philosophical stance, it is up to us to accurately discriminate in which different respects transcendental claims are involved or not in objecting to the methodological stance of naturalism. This imperative is useful for us: will the apriorism claim (see Kant’s definition of transcendental philosophy above), or rather “transcendental idealism” (with its corresponding claim that a transcendental logic constitutes objectivity on the basis of subjective acts, and the assumption of appearances departing from “things in themselves”), take precedent in our own investigation?

And lastly: this attests that such a debate was already underway long before twenty first-century philosophers began to consider the issue.

Corresponding author: Charlotte Morel,CNRS, UMR 8547 – ENS, 45 rue d’Ulm, Paris75005, France, E-mail:


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Published Online: 2019-12-27
Published in Print: 2020-03-26

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