1 Introduction

Driven by problems concerning the foundations of mathematics, Husserl begins his studies in philosophy not with Plato and not as a Platonist. Husserl’s older friend—later to be a founder and the first president of Czechoslovakia—Thomas Masaryk urged him to read modern philosophers like Leibniz and the English empiricists (Schuhmann 1977, 5) and Husserl follows this advice: “I occupied myself intensely with Locke, Berkeley and especially Hume again and again, on the other hand with Leibniz; I made an unsuccessful stab at Kant, and rather read Laas’ critiques of Kant, the positivist motives of which repelled and attracted me at the same time” (pencilled on the second draft of an introduction to the LI, Husserl 2002a, 430). It was Lotze who broke this fixation on modern thinkers and gave Husserl the “decisive impulse” (Husserl, 2002a, 414; cf. 417) of Platonism.

Even though Husserl never considered himself a follower of Lotze (Farber 1943, 207), he clearly states the influence of Lotze several times. In a book review from 1902 he says about Lotze that “especially those of his thoughts surrounding his interpretation of Plato’s theory of Forms had a strong influence on me” (Husserl, 1979, 156). He shows the same appreciation of Lotze’s “interpretation of the Platonic doctrine of Forms” (Husserl, 1984, 138, fn. 3) in the second edition of the Logical Investigations in 1913. The most poetic acknowledgment can be found in a fragment of an intended preface to this second edition:

The absolutely conscious and radical turn and the “Platonism” it was accompanied by, I owe to the study of Lotze’s logic. As little as Lotze himself got beyond its contradictory inconsequences and psychologism, his inspired interpretation of the Platonic doctrine of Forms nevertheless put up a bright first light and determined all further studies. (Husserl 2002a, 297)

Confronted with this almost exuberant praise and the usual Husserlian vagueness regarding his references and sources, one is inclined to ask what exactly Husserl is grateful for. What is this “light” that Lotze put up—or what did Husserl see in its rays?

In the following I will firstly give a brief sketch of Lotze’s (highly problematic) interpretation of Plato’s so-called doctrine of Forms as he presents it in the second chapter of the third book of his Logik, called “Die Ideenwelt” (section two). Secondly, I will discuss what Husserl took from Lotze or may have taken from him. In the course of these deliberations, I will also try to show that Husserl thereby—initially—credits Lotze’s chapter “Die Ideenwelt” of his Logik by presenting an account Lotze actually rejects, even though he needs it from a phenomenological point of view (section three). Finally, I will try to sketch how Husserl’s (mis)reading of Lotze brings him much closer to Plato’s original Platonism than Lotze’s “light” ever reached (section four). In some sense this paper is therefore about a misreading of a misreading.

2 Lotze’s Platonism

Regarding the historical understanding of Plato’s philosophy, Lotze offers the picture of a Socratic-Platonic reaction to several forms of scepticism as exhibited by the Heraclitean school and many of the Sophists. While Socrates’ “healthy sense of truth” led him to engage scepticism in ethical matters, Plato “developed” or “broadened” the anti-sceptical strategies of his teacher into his so-called doctrine of Forms (Lotze 1989, 506). Lotze explicates this doctrine of Forms as revolving around a notion of a priori truth (Rollinger 1993, 31), a “truth” independent of any correspondence with (supposedly) real things (Lotze 1989, 506), a “truth” thus untouched by the Heraclitean flux of actual experience (Lotze 1989, 508).

The thesis that there are such “truths in themselves” as Husserl later puts it, we shall call “logical Platonism” (Bernet et al. 1993, 34), because it claims absolute or eternal (Platonic) validity for certain propositions (logoi) or truths. Note that this logical Platonism constitutes a much stronger claim than truth−theoretical realism, although it includes the latter in regard to a certain class of propositions (but see Beyer 1996, 132 for a different view). The difference between logical Platonism and truth−theoretical realism lies in the following: While truth−theoretical realism asserts that true (or valid) propositions are true (valid) regardless of “whether [they] become the object of knowledge in the actuality of being−thought−about [Wirklichkeit des Gedachtwerdens]” (Lotze 1989, 514) or not, logical Platonism includes assumptions about certain attributes of and possibilities of access to certain truths, say, through logical intuition, reflection, or demonstration. Logical Platonism asserts the existence of a priori truths which we can access, whereas truth−theoretical realism just states that true propositions are true regardless of our activity. The latter has nothing to say on our abilities to access truths nor on the quality of truth (be it absolute or a priori), so to speak.

Examples of such “eternally valid true propositions” (Lotze 1989, 509) include truths about the relations within tone- or colour-scales that will stay true no matter how our experience develops or even if we lack further experience about tones and colours. A high C will always be lower than a high D, no matter what music we might hear or miss hearing; and “this is exactly what Plato wanted to teach: the validity of truths irrespective of whether any thing in the outer world instantiates them” (Lotze 1989, 513). Because of this independence from the factual reality of the outer world, we are not forced to rely on our treacherous senses to grasp and assess these true propositions, allowing us to form an “unchangeable system of thought” immune to scepticism regarding the outer world (Lotze 1989, 508). Thinking alone gives us access to this realm. It is important to take the implications of the metaphor of access seriously: access is only ever access to something that pre-exists before our accessing it; this means we are not the creators or producers of this kind of truth, it is not relative to our thinking and we ourselves are well aware of this fact, for “at the moment in which we think the content of a truth we are all convinced that we did not create but only accept it” (Lotze 1989, 515). This “independent validity of ideas” therefore also saves the truths Lotze has in mind from the kind of “relativity” Protagoras and the other sophists propounded (Lotze 1989, 515).

The notion of validity is of great importance to Lotze because it allows him to save Plato (or at least his own logical Platonism) from the traditional charge of hypostasization—although he quite rightly points out that these charges rarely clarify “into what” (Lotze 1989, 516) exactly Plato supposedly hypothesised his Forms. For his own defence he distinguishes four kinds of “actuality [Wirklichkeit],” “none of which can be reduced to the other or is contained in them” (Lotze 1989, 512). The actuality of things is being(sein); the actuality of events is to take place or to happen (geschehen); the actuality of relations is to obtain (bestehen); the actuality of propositions is to be valid (gelten). Based on this classification Lotze explains that all accusations of hypostasization really rest on ascribing the wrong kind of actuality to truths in themselves. While they exhibit the actuality of validity, even eternal validity, they do not actually exist, i.e., they lack the actuality of being (Lotze 1989, 514). It is exactly this discovery of “universal truths that are not like things but still govern the behaviour of things” that Lotze considers to be the “great philosophical feat of Plato, how many questions it might have left unanswered” (Lotze 1989, 520). How Platonic this fourfold ontology and defence of logical Platonism really is will concern us in the last section.

According to Lotze, in using the metaphor of the place beyond heaven (hyperouranios topos) Plato does not try to “hypostasise their mere validity into some kind of reality (being-actual)”; instead the use of the metaphor constitutes “the clear effort to prevent any such attempts in the first place” (Lotze 1989, 516). In this, however, Plato was hampered by the fact that he did not have the notion of validity at his disposal, due to Greek lacking it or similar expressions—a lack that necessarily lead to severe misunderstandings about the ontological claims inherent in his doctrine of Forms (Lotze 1989, 514).

Regarding the Forms themselves Lotze admits that it is only “half clear” how to apply the notion of validity to singular concepts or ideas which only “have meaning” (Lotze 1989, 521). This makes Lotze’s reconstruction of the doctrine of Forms highly problematic, since in his own view Plato cared almost exclusively about the “isolated concept or the idea” (Lotze 1989, 521) or at the most tried to establish a “classification of ideas” (Lotze 1989, 522), compiling single specimen of the “flora of ideas” (Lotze 1989, 523) instead of dealing with the rules governing their connections.

Thus, Lotze effectively ends up speaking about something Plato had—on Lotze’s own account –only a derivative interest in (namely, propositions), using a concept he did not and could not employ (validity). Lotze’s way of saving his holistic interpretation (Hartimo 2019) is to understand the meaning of the Forms as a function of the validity of propositions about them, thus reversing the order of priority (Rollinger 2004, 158): “they mean something because certain propositions about them are valid” (Lotze 1989, 521), so the “main components of the ideal world” (Lotze 1989, 521) are still propositions, while Forms only function as non-independent building blocks and relata. This analysis of the proper logical function of the Forms provided by Lotze makes sense from a truth-functional approach to semantics: forms have meaning because some propositions about them are true (or valid, in Lotze’s terminology); one might add that they can be considered eternal only because the propositions in question never change their truth-value or validity. From a phenomenological perspective this line of thought is quite unsatisfactory as we will see in the next section.

Lotze himself describes the Ideas or Forms as “independent content, always meaning what it means, and whose relations to others keep their identical eternal validity” (Lotze 1989, 507) or as “quality,” “eternally self−identical” (Lotze 1989, 507), so that opposed to the Heraclitean flux they “had to be called eternal, neither coming into being nor vanishing,” “untouched by change“ (Lotze 1989, 514). At the same time Lotze marginalises them, degrading them to be mere non-independent components of propositions. Ideas “are not part of what we call the real world” (Lotze 1989, 516), yet they are not full citizens of the “Ideenwelt” either, since the “independent validity of ideas” (Lotze 1989, 516), which is “their proper mode of actuality” (Lotze 1989, 514) is not really independent after all, but rather derivative of the validity of propositions, and, as quoted above, Lotze himself admits that strictly speaking Ideas are not proper subjects of validity. But then again Lotze openly admits to explaining what Plato should have said rather than what he actually said (Lotze 1989, 522)—quite in contrast to Husserl, who believes his own philosophy to be the fulfilment or realization of Plato’s initial idea of philosophical inquiry (e.g., Husserl 2002b, 302, 365; see Arnold 2017).Footnote 1

3 Husserl’s Platonisms

Husserl takes over Lotze’s view of the “socratic reaction” (Husserl, 2012b, 25) to sophist “anti-philosophy” (Husserl, 2012b, 12) by the “binary star Socrates-Plato” (Husserl, 1956, 8; Husserl 2002b, 52) with Socrates as the “practical reformer” (Husserl, 1956, 9; see also Husserl 1988, 36) and Plato as the “theoretical [wissenschaftstheoretischer] reformer” (Husserl, 1956, 9; see also Husserl 1974, 5), who both took the challenge of scepticism seriously, although they missed the “transcendental impulse” inherent in scepticism (Husserl, 1956, 74; Husserl 1987, 127).

Systematically Husserl accredits two prima facie similar and closely related but really quite distinct forms of Platonism to Lotze’s chapter on the “Ideenwelt” in his Logik. The passage from the intended preface quoted above continues like this: “Lotze himself spoke of truths in themselves [Wahrheiten an sich] and so it stood to reason to move all things mathematical and most of what traditionally belonged to logic into the realm of ideality” (Husserl 2002a, 297). With “truths in themselves” Husserl refers to Lotze’s idea of “eternally valid true propositions” (Lotze 1989, 509), that is, logical Platonism. In addition to a conception of truth, Husserl assumes that Lotze also presents a first take on “‘ideal’ meanings, the ideal contents of imagination and judgment [Vorstellungs− und Urteilsinhalten]” (Husserl 1979, 156).

The influence of this logical Platonism is most obvious in the Logical Investigations (Moran 2008, 410), since it is here that Husserl tries to save the timeless validity and the necessity, i.e., the apriority of logical laws and theorems from the vagaries of psychologism, which shares basic traits with Protagoras’ “original notion” (Husserl, 1975, 122) of subjectivism and relativism. Against Sigwart and other contemporary relativist thinkers, Husserl defends a realist conception of (logical) truth as a “unit of validity in the timeless realm of ideas,” which “is valid while we still have not discerned it and maybe never will discern it” (Husserl, 1975, 136), i.e., truth in itself as applied to logical and mathematical propositions. It was this notion of truths in themselves which also allowed Husserl to properly appropriate Bolzano’s ideas: “Step by step I could […] prove the “platonic” interpretation in regard to Bolzano’s account, which Bolzano himself would have found quite abstruse” (Husserl 2002a, 298; see also Husserl 1971, 57 and Husserl 1979, 156).

Lotze’s lessons did however not just influence Husserl’s reading of Bolzano. “After critically cleansing the Lotzean-Platonic doctrine of Forms, Hume’s relations of ideas turned out to be essential laws [Wesensgesetze]” (Husserl 2002a, 290). Hume had shown Husserl that the workings of the mind could be explored, Lotze’s logical Platonism then allowed him to conceptualise the rules governing these relations of ideas as eidetic laws and the truths about them as a priori truths. The main point here being that Lotze showed Husserl not only the possibility of a priori truths in general but of truths a priori outside mathematics or formal logic; as Husserl points out, Lotze’s examples all stem from the “realm of sense−data” (Husserl 2002a, 303), which impressed Husserl strongly (Husserl 2002a, 417), as it showed him how material eidetic sciences would be possible, i.e., eidetic research that is neither mathematical nor bound to the mere form or formal structure of subjectivity. Put briefly, this difference concerns the kind of essences and essential truths under consideration. Mathematics is a group of material eidetic science, as it concerns essential properties and relations between specific mathematical objects (or groups of objects), not just formal ontological issues. It is also exact and deductive; its objects and methods can be defined and they result in a priori truths. However, we can also investigate essential structures in other realms whose elements are less defined and definable, for example those of consciousness and the lifeworld (see Sokolowski 1979). Hence, Husserl distinguishes between material eidetic sciences that are mathematical, and those that are not and which he labels as descriptive morphological sciences (as opposed to the exact sciences). The important point being that both groups of sciences equally concern eidetic structures and hence aim for essential knowledge and a priori truths, despite their difference in exactitude and methods. But this claim of equality rests on the possibility of a priori truths outside the realm of pure mathematics.

Lotze’s insight regarding such truths constitutes one of the reasons why Husserl eschewed the (Neo−)Kantian conception of the a priori in favour of a Platonic one (Husserl 1956, 199; see also Kern 1964, 143; Tugendhat 1970, 163): any given object can give rise to a priori truths once its essence or eidos is understood (De Palma 2014, 207 ff.). Other phenomenological reasons to reject the (Neo−)Kantian notion of the apriori include its supposed hidden anthropological contamination and the inability to accomodate Husserls eidetic method, including the Ideenschau (see Husserl 2012a, 88; Arnold 2017, §18b).

Establishing logical Platonism was certainly Lotze’s main project in the chapter on “die Ideenwelt” as we saw above. But while Husserl did indeed employ and defend notions of validity, truth and meaning partly inspired by Lotze in his discussion of psychologism in the Logical Investigations (although he clearly departed from Lotze in certain regards, see Dastur 2017, Huemer 2004), his logical Platonism was not Husserl’s main gain from his reading of Lotze. To the long passage from the draft of an introduction to the new edition of the Logical Investigation quoted above Husserl added the following in pencil:

My thoughts were stuck on the problem of evidence and in the end I was only able to say: “truths of reason (Vernunftwahrheiten)” are a “seeing” of relations between ideas, but not ideas as Hume defined them; rather the universal fact is perceived und this perception is a self-givenness, a seeing, just of a different kind than ordinary seeing. Only Lotze’s interpretation of Plato’s theory of Forms encouraged me to take this seriously and accordingly posit Ideas as objects. […] And just as mathematics is now a science of ideas, there have to be such sciences in all spheres of being, even those outside the mathematical ones. From the beginning a region of apriori knowledge of being showed itself in Lotze, that of sensual givenness. (Husserl 2002a, 430 − 31)

The easily overlooked difference between this passage and the one quoted at the beginning of this section consists in the fact that Husserl here talks about “Ideas” instead of truths, and “spheres of being” rather than validity. Since “Ideas” here apparently includes mathematical entities and essences of non-mathematical objects like colours (“sensual givenness”), to “posit Ideas as objects” is obviously very different from claiming the existence of ideal meanings and truths in themselves; truths or propositions belong to a different class of objects than and thus behave very differently from essences or numbers for example. We shall call the assumption that ideal objects (or eidê or Ideas or Forms) are proper objects, “ontological Platonism.” We will deal with Husserl’s own account of Forms in the last section, suffice it to say that logical Platonism and ontological Platonism are two different theorems, both of which Husserl apparently found in Lotze’s Logik—at least according to his drafts and notes surrounding the second edition of the Logical Investigations.

In Ideas III however we find a more nuanced view. Here Husserl notes that Lotze

lacks, on a closer look and without reading something into his beautiful deliberations that is quite alien to them, the true concept of essence [Wesen] as it can be grasped by eidetic intuition [Wesensintuition], that could constitute an absolute measure [Maß] of truth. Occasionally he touches upon this notion, only to drop it in favour of completely worthless concepts of the apriori. (Husserl 1971, 58)


Husserl seems to have realised that Lotze does not in fact offer an account of ontological Platonism and (implicitly) admits to reading something into Lotze by ascribing a theory of essences to him. He certainly thought that Lotze himself did not develop his Platonism consistently (see Fisette forthcoming).

More importantly Husserl points out a possible connection, even an asymmetrical relation of foundation between the two Platonisms: the truth of a proposition is measured by our proximity to the object the proposition is about (its adequacy), and only ideal objects offer the kind of “absolute measure” truths in themselves require to be as absolutely true as they are supposed to be. From Husserl’s perspective all a priori truths are about essences, i.e., ideal objects or Platonic Forms or eidetic structures. Every “aprioric science” is necessarily “eidetic science” (Husserl 1976, 8) and on the most basic level, any notion of apriority is determined through the idea of the eidos (Husserl 1974, 255 fn.1; Husserl 2002a, 415), not validity or truth, since truth is “fundiert,” i.e., based on the lower−level constitution of its thematic objects. If there were no ideal objects like mathematical entities or colour−essences, logical Platonism would lose all footing, since truths about spatio−temporal affairs would in this case still be true−and would still be true regardless of what we thought about them, as long whatever state of the world they pertain to persists−but a priori truths would have no objects to be true of. In a world without Forms, that is, in a world of Heraclitean flux no “unchangeable system of thought” (Lotze 508) of “eternally valid true propositions” (Lotze 1989, 509) is possible.

So, while Husserl’s earlier (mis)reading of Lotze as presenting both forms of Platonism might indeed be just an exegetical slip-up caused by a biased or perfunctory reading, systematically it was a necessity from Husserl’s point of view, because for Husserl the possibility of truths in themselves or a priori truths, implies the existence of Ideas as described by Plato. This is most obvious in the case of mathematics (and logic), since for Husserl, mathematics is without a doubt about eidetic objects or relations, so any mathematical truth refers to an ideal object or relation. But even more generally, logical Platonism implies ontological Platonism. Husserl’s earlier ontological (mis)reading of Lotze’s interpretation of Plato thus provides and clarifies the ontological basis required for logical Platonism. If it is a misreading, it might well be a conscious one. Lotze himself apparently missed this basic connection when he tried to marginalise the Forms, but, as he himself says, “coming to understand the simplest relations of thoughts is not the simplest deed of thinking” (Lotze 1989, 518).

Yet even if he did not accept Lotze’s whole take, Husserl’s recognition of the impact it had on him has to be taken seriously and his ontological Platonism indeed still owes a lot to the chapter on the Ideenwelt. Two features stand out most clearly.

  1. 1.

    Husserl’s notion of ideality presumably derives from or at least is in debt to Lotze’s concept of validity (Hartimo 2019). It certainly shares the Platonic trait of timelessness, since eidê for Husserl are “transtemporal” unities, although given in the mode of universal temporality (Husserl 1999, 313), where Lotze speaks of the “eternal validity” of relations and propositions. It also serves the same (negative) strategic purpose, namely that of steering clear between the Scylla of reification and the Charybdis of mentalisation. In Lotze, the validity of truths in themselves is a kind of actuality that “denies the actuality of being as well as maintaining independence from our thinking” (Lotze 1989, 512); propositions are neither (real) things nor (mental) events. And although Husserl rejects Lotze’s approach of reducing the actuality of the sphere of the ideas to validity, his aim is also to avoid the “two misunderstandings” (Husserl 2002a, 127) that have “hampered the development of the doctrines of universal objects,” only now in regard to the ontological status of essences or Forms rather than the status of the propositions about those essences, i.e., metaphysical hypostazation (i.e., reducing ideal or eidetic objects to real objects, see De Santis 2016) and psychologism or nominalism (i.e., reducing ideal objects to mental episodes or concepts). So, while Husserl disagrees with Lotze about the positive account of the ontological status of Forms or ideal entities, he shares the latter’s negative goal of avoiding certain misunderstandings and reducing ideality to either physical or mental reality.

  2. 2.

    Although Lotze mentions it only once and in passing, he presents a thought that possibly had a huge influence on Husserl’s notion of essences, even if Husserl never mentions Lotze in the relevant context. Concluding his discussion of sundry examples of truths in themselves, Lotze stipulates that “the eternal relations holding between the individual Ideas which allow some to be compatible and force others to be incompatible, constitute at least the boundaries of what is possible in perception” (Lotze 1989, 509). Together with his repeated assertion that the truth of the truths in themselves is independent of any connection to reality (Lotze 1989, 506, 508, 509, 514, 515), this gives us a regional version of Husserl’s more general principle that essences are pure possibilities: “The eidos is truly pure only once any tie to a pregiven reality is diligently cut” (Husserl 1968, 74), it might therefore indeed be called “validly hypostasized possibility”; in fact every eidos is nothing but “pure ideal possibility” (Husserl 1966, 403). Husserl’s whole concept of eidetic variation is nothing if not the attempt to create a method or technique for freeing any universal concept from its−possibly hidden (Husserl 1968, 74)−ties to the “narrow sphere” (Husserl 1959, 342; see also Husserl 2012a, 311) of our actual world, i.e., reality, thus recovering its true eidetic content. Lotze’s emphasis on the irreality and the possibility−constituting or boundary character of the Ideas could very well have helped shaping this phenomenological take on essences, even though the development of the correlated model of variation took shape a long time after Husserl had read Lotze, culminating in Experience and Judgement.

One of the very few criticisms Husserl offers against Plato can also be traced back to Lotze’s critique of Plato’s account of the realm of Forms as focusing too narrowly on the botanical classification of Forms while ignoring their propositional role. In a note on the ideality of Ideas from 1918 to 1920 Husserl writes “Plato got stuck in questions about the classification and ordering of the Forms as universal objects, without being able to get through to the crucial demarcations even here. Because these only become accessible with the function of Forms in the form of universal predicates in universal judgements!” (Husserl, 2012a, 117) This clearly echoes Lotze’s charge of “incompleteness” (Lotze 1989, S. 521) in regard to a philosophy of judgement against Plato’s original take on the Forms. Husserl even goes so far to indicate that Plato did not even consider the logos to be an eidos, an “ideal identity” in itself−which is blatantly false, as we shall see below.

4 Plato’s Platonism

How close to Plato’s original form of Platonism did Husserl get through reading Lotze’s interpretation of the so−called doctrine of Forms? Since Husserl shares Lotze’s criticism of Plato’s treatment of propositional structures, as we just saw, let us consider this charge to begin with. Both seem to think Plato missed the role Forms play in the formation of a priori truths because he did not attend to the essence of propositions. This line of critique is mistaken, although understandably so. In some dialogues of the middle period eidetic intuition seems indeed to target a single Form at a time, like the Form of the weaver’s shuttle in the Cratylus or the Form of beauty in the Symposion. But while a cursory reading of some dialogues might lead to the impression that Plato was solely concerned with particular Forms, Plato was in fact fully aware of the “predicative function of the eidos” (Oehler 1962, 66), as for him true essential judgements are exactly expressions of relations between Forms (Oehler 1962, 53). A predication like “justice is a virtue” expresses the eidetic fact that the Form of justice participates in the Form of virtue. And speaking more generally, “only through mutual interweaving of essences can [philosophical] speech (logos) come to be” (Sophist 259e).

In light of his account of the necessary interweaving and mutual participation of the highest Forms (the symplokê of the megista genê) as presented in the Sophist it is doubtful whether Plato even considered the possibility of an “isolated […] Idea” (Lotze 1989, 521), as each Form gains its unity by not being everything else (Sophist 257a), i.e., by standing in a relation of negation to every other Form. Plato thereby propounds a version of Spinoza’s “omnis determinatio est negatio.” The heaven of Forms is to be conceived of as something Hegel would call a concrete totality, each Form connected to all the others via the range of relations that make up part of the megista genê, at least through negation or difference.

Additionally, all the major discussions of the Forms in Plato’s work deal with issues of eidetic connectivity, like the question whether the Forms of the particular virtues all partake in a Form of virtue as such (in the early dialogues and the Republic), or whether the soul can partake in death, since it already partakes in the Form of life (in the Phaedo), or the issues surrounding the connection between the One and its other (in the Parmenides).

As regards the charge of neglecting the structure of propositionality, Plato explicitly states the logos to be one of the megista genê and therefore an eidos in its own right (Sophist 260a). Following the discussion about the connection of the megista genê Plato sketches an account of the structure and function of propositions, including the conditions of truth and falsity. So even if he lacks the concept of validity, he certainly neither marginalises the topics of propositions and predication nor the problems surrounding the idea of eidetic participation. In this case, following Lotze’s “light” led Husserl away from a correct understanding of Plato, who surely was as much a logical Platonist as Lotze and Husserl.

In respect to ontological Platonism things look very different. Here we have to distinguish a negative and a positive side to Lotze’s, Husserl’s, and Plato’s take on Forms.Footnote 2 As we saw above, both Lotze and Husserl agree on the necessity to distinguish the Forms from real, i.e., perceivable spatio-temporal things on the one hand and subjective mental episodes or thoughts on the other. This is perfectly in line with what Plato has his interlocutors say. Especially Husserl’s efforts to navigate between the Scylla of mentalising the Forms and the Charybdis of reifying them closely mirror Plato’s approach to warding off incorrect interpretations of his teachings as presented in the Parmenides and the Sophist.

In the former dialogue a young Socrates initially conceives of eidetic participation as a mereological relation: each instance of an idea has a particular part of that very Form within it, which covers all its instances like a sail (Parmenides 131b). The consequence of this very literal conception of the “one-over-many” would of course be that the Form would stop being one and the same for all its examples; no two examples of the Form in question would actually be instances of the very same eidetic structure since they would share it through different parts. But Forms are not thing-like as they do not have real parts. Socrates then tries to escape the aporia of what was later called the “third man” (Aristotle 1924, Metaphysics 1079a13, 1039a2, 1059b8) by equating Forms with thoughts. To which the old Parmenides replies “a thought about nothing?” A few lines later Socrates has to admit that the Forms might be objects of thought but can never be identical to them (Parmenides 132b). The Forms are the objects of eidetic intuitions and the topic of dialectical discourse, yet they are not simply identical with either intuitions or discourse.

In the Sophist the stranger from Elea discusses the gigantomachia between the “earthborn,” i.e., materialists and the “friends of the Forms,” whose position either represents Plato’s earlier teachings or some un-Platonic interpretation thereof (Sophist 246a). While the earthborn (try to) deny the existence of anything other than that which they can touch and see, the friends of the Forms seem to conceive of the Ideas as some kind of ethereal things or invisible substances lingering in some sterile Beyond; both positions are dismantled in the course of the discussion. Incidentally Husserl must have known these passages quite well, judging from the markings in his editions of the dialogues (BA 1351 and BQ 365 in Leuven, see Arnold 2017, § 2b).

Concerning the positive account of the ontology of Forms however, Lotze, Husserl, and Plato part ways. While Plato and Lotze both in some sense propound a fourfold ontology, it is impossible to map Lotze’s four kinds of actuality onto the onto-epistemological hierarchy as presented in the analogy of the divided line (Republic 509d): Socrates offers a ranking of being-ness and the correlated epistemic possibilities in which the Forms take the highest place, because they exhibit the most being and can thus alone be properly known. According to Socrates, the Forms are eternal, i.e., removed from the flow of time, self-identical, and non-multipliable, which distinguishes them from numbers.Footnote 3

Lotze on the other hand tries to distinguish certain kinds or types of actuality, not being-ness. This—as we saw above—leaves him incapable of accounting properly for the ontology of the main object of the various Platonic reflections on the Forms, that is to say the Forms themselves. He is certainly unable to accommodate their peculiar “actuality” into his fourfold division of being, taking place, obtaining, and being valid, since being is reserved for real things and validity for true propositions. And even though he tries to avoid reducing Forms to thoughts and wants to hold on to a form of truth-theoretical realism, his fear of a certain brand of outer-world-scepticism leads him to limit his truths in themselves to the “world of our imagination [Vorstellungswelt]” (Lotze 1989, 506). His strategy consists in giving the outer world of the Heraclitean flux to the sceptic while keeping the realm of truths accessible to “inner perception [innerer Anschauung]” (Lotze 1989, 509) alone. By this trade-off he hopes to establish a kind of anti-sceptical acropolis within the mind. But while Plato indeed thinks that the realm of perceivable things is in flux and its objects are incapable of being fully known, the Forms are, as we saw above, not just dwellers of our personal mind-space.

Also, the main distinction present in many Platonic dialogues is not mind/world or inner world/outer world but being/becoming, correlated with thinking and knowledge/perception and conjecture.Footnote 4 Instead of accepting Plato’s framework and his descriptions of the peculiar mode of being of the eidê as a unique ontological status, Lotze tries to force his category of validity onto the Forms to fit his peculiar anti-sceptical strategy.

Which is why Husserl, who writes that eidetic structures “cannot be described in other words than those which Plato used in his doctrine of Forms: as eternal, self-identical, as non-temporal, non-spatial, unmoving, unchangeable etc.” (Husserl, 1996, 34) rejects Lotze’s fourfold division (while at the same time retaining logical Platonism, see Hauser 2003, 164). Instead, he accepts ontological Platonism, positing the Ideas as proper objects in their own right, reinstating the “birthright of the eidetic [Eigenrecht des Eidetischen]” (Husserl, 1976, 146) against the “Idea-blindness” (Husserl, 1976, 49) of contemporary philosophies—among which Lotze’s interpretation of Plato must at least partially be numbered.

Husserl tries to achieve an adequate understanding of “Ideas as objects” by clarifying and broadening the concept of “object” (see Arnold 2020). His concept of objectuality is accordingly less narrow than Lotze’s understanding of thing-ness (re-ality), so that granting object-status to Ideas does not imply their being (in Lotze’s sense) or their reality, as Husserl states clearly in his famous defence against the charge of “Platonism” in § 22 of Ideas I:

If object and real thing, actuality and real actuality mean the same, the conception of ideas as objects and actualities really constitutes a case of twisted “Platonic hypostazation.” But as long as they are clearly distinguished, as is done in the Logical Investigations, and as long as object is defined as something, for example as a subject of a true […] proposition, what offence could remain—except one stemming from dark prejudices?

By abandoning Lotze’s fourfold distinction of different types of actuality in favour of his ontological Platonism, Husserl actually keeps in line with (and maybe even succeeds) Lotze’s original attempt to secure and understand “the existence of an eternally valid substantial world of Ideas” (Lotze 1989, 523), because he can offer an account of the Forms which is neither deflationist (as is Lotze’s) nor burdened with metaphysical misinterpretations (like nominalism or metaphysical realism). By ignoring Lotze’s attempt to explain away the unique ontological status of the Forms and instead positing them as proper objects qua possible “subject[s] of true propositions,” Husserl also got closer to Plato’s original concept of the eidos as an object of (philosophical) thought, a purely intelligible entity (Phaedo 78e; Republic 507b), a “noêton” (Republic 509d)—as Husserl himself surmises in Experience and Judgment (1999, 411).

5 Conclusion

So what did Lotze’s “bright light” reveal to Husserl? Most importantly it highlighted the possibility to conceive of essential truths in themselves outside the realm of mathematics or logic. But while Husserl at some point had to admit that Lotze’s interpretation of the so-called doctrine of Forms does not yield what we have called ontological Platonism or even runs contrary to it and is therefore at odds with Husserl’s own treatment of eidetic or ideal structures as proper objects, his phenomenological account of ideality still benefited from Lotzean thoughts, namely from Lotze’s attempt to avoid the reduction of the “world of Forms” to either physical or mental reality, as well as from Lotze’s idea that Forms constitute the modal boundaries of reality. Regarding the proximity to Plato’s original position, stepping outside the range of Lotze’s light probably got Husserl closer to the archetype than staying within its beam.

On behalf of all authors, the corresponding author states that there is no conflict of interest.