1 Introduction

What are colours? A standard position in the metaphysics of colours, defended by both philosophers and cognitive scientists, is subjectivism, which takes colours to be precisely “subjective” entities. On this view, reality is made of various kinds of particles, among them photons, that is, particles of light; photons have causal powers, including that of acting on our visual system. When they do so, they produce specific appearances that we call “colours” (for more details on the complex psychophysiological process of colour vision, see Palmer, 1999). Given this dependency of colours on our sensory organisation, that is, on us as sensory subjects, colours are described as “subjective” or “psychic” properties, and are thus contrasted with “physical” ones. This is the case in Palmer, for example, who claims: “Color is a psychological property of our visual experiences when we look at objects and lights, not a physical property of those objects or lights” (Palmer, 1999: 95, quoted in Byrne & Hilbert, 2003: 4a). In short, given their dependency on our physiological constitution, colours are psychic entities and not physical ones.

At the turn of the twentieth century, similar views were criticised by Adolf Reinach, a member of the early phenomenological tradition.Footnote 1 This tradition is made up of Husserl’s earlier students – in addition to Reinach, Moritz Geiger, Alexander Pfänder and Edith Stein, among others – and it criticises the developments of Husserl’s later idealistic-transcendental phenomenology by defending metaphysical realism (for more on this tradition, see Salice, 2020). Reinach is opposed to the thesis that colours are subjective or psychic. More precisely, he thinks that subjectivism about colours is wrong regarding the “What is it?” question, or the question, “What are colours?”, that is, the question about the nature or essence of colours. With respect to their essence, Reinach says, colours are not subjective, but are indeed physical. However, there is another sense in which it might be legitimate to describe colours as “subjective”, namely, in the sense that they exist only as appearances and not in reality. But this sense, he argues, is not the same as “subjective” understood as “psychic”. Subjectivists, Reinach adds, do not distinguish between these two senses of “subjective”, and thus wrongly conclude on the basis of the non-existence of colours that they are essentially subjective or psychic.

Interestingly, Reinach does not take a stance on whether colours exist in the outer world. That is, he does not feel compelled to decide that question. Thus, he adopts what I call “ontic-neutral essentialism” about colours, claiming the following: we know what colours are according to their very essence or nature, namely, physical entities, though it might be the case that those we see are mere appearances and do not exist in the outer world. In other words, he argues that one can be neutral about the existence of colours and still have a developed account of their essence.Footnote 2

In the next section of the paper (§ 2), I will present Reinach’s insights about the essence of colours. I will first present Reinach’s thesis that colours are physical entities and explain his motivation for defending it (§ 2.1). I will then explain what kind of physical entity Reinach claims that colours are, and I will show that he takes colours to be “primitive” physical entities that appear to us in our visual experience, and not some kind of “micro-structural” entity as found in a physicalist worldview (§ 2.2). In the third section (§ 3), I will focus on the question of the existence of colours. I will first present some criticism made by Reinach against non-realism about colours (§ 3.1); I will then present Reinach’s ontic-neutral essentialism and point out an interesting distinction that one can draw from it regarding the existence of colours, namely, between empirical and metaphysical non-realism about colours (§ 3.2).

2 The essence of colours

2.1 Essential non-subjectivism

A crucial claim made by Reinach is that “subjective” is an equivocal term that has at least two meanings, which people confuse when they talk about colours. In one sense, “subjective” refers to I’s, or egos, such as you and me, and to their properties, for example, a feeling of joy. In this sense, what is subjective is opposed to what is physical, that is, to spatial objects and their (extended) properties, for example, a stone and its shape. In another sense, “subjective” refers to everything that is mind-dependent, that is, that which only exists to the extent that it is thought of.Footnote 3 In this sense, “subjective” is opposed to “objective”, or mind-independent. Reinach thinks that colours are not subjective in the first sense, but rather are physical. And he thinks that this is a separate question from whether colours are subjective in the second sense; that is, even if they were mind-dependent, they would remain physical. Let us see more precisely how he comes to defend this view.

The idea that colours are not subjective or psychic but physical is straightforward for Reinach. He presents the idea as follows (in a text from 1913 [1989d], Einleitung in die Philosophie, 378):

The theory of subjective sensory qualities is not always clear. One here means very certainly no psychic nature; sensory qualities in any case are not psychic things. A feeling of joy or grief is very certainly something psychic. Colour, by contrast, has a place in space and presents itself in front of us as something foreign with a claim to independence (be it justified or not). A feeling does not ‘appear’, does not ‘present itself in front of us’. Properties of the I in volitions, feelings, and so on are functions of the I, and belonging to the I is characteristic of what is psychic. Colour, by contrast, is objectual.

Note that for Reinach (Einleitung in die Philosophie, 378) properties in space, such as colours, are “physical” properties; thus, he here draws a general distinction between what is psychic and what is physical. According to Reinach, physical properties are in space and appear as “foreign” (i.e., extrinsic to the perceiving subject) and independent; they belong to (spatial) objects.Footnote 4 Psychic properties, by contrast, are functions of the I, and belong to the I; that is, they are properties of an ego and can be predicated of it.Footnote 5 Colours cannot be so predicated; rather, they are predicated only of extended objects. For indeed, colours are in space, which is the mark of what is physical. For Reinach, then, colours are not subjective or psychic entities, but physical ones.

But aren’t colours subjective in another sense, namely, in the sense that they do not exist mind-independently, but only to the extent that we have visual experiences of them? Reinach addresses this question, and in doing so follows views found among other members of the early phenomenological tradition. Considering the views of this network of authors will help us to better understand his claims, which are sometimes more scattered than those of his colleagues.Footnote 6 The issue is discussed by Geiger, another early phenomenologist, who claims (in a text from 1930 [1966], Die Wirklichkeit der Wissenschaften und die Metaphysik, 22–3) that colours are not “subjective-psychic”, that is, they do not belong to a subject (or as Geiger puts it, they do not have Subjektszugehörigkeit). However, they might be “subjective” in the sense of “subject-dependence” (Subjektsabhängigkeit). “Subject-dependence” here means mind-dependence, that is, being a mere objectual correlate of a mental act. It might be the case that colours are subjective in the sense of being mind-dependent, but this sense of “subjective” should be clearly distinguished from the other sense, namely, belonging to a subject.

Pfänder, another early phenomenologist, carefully distinguishes these two senses of subjective and explains how they apply to colours. It is worth quoting him at length (from his 1904 Einführung in die Psychologie, 296–7):

To be sure, sensations are also “subjective”. But here the word “subjective” has an entirely different meaning compared with when one describes the objects of sensation as “subjective” from an epistemological (erkenntnistheoretischen) point of view. When one refers to sensations, that is, e.g., seeing, as “subjective”, nothing here is decided about the reality value of seeing from an epistemological point of view, but it is only said that seeing and sensations in general include in themselves a psychic subject. In this sense, however, the word “subjective” means the same as the word “psychic”; for what is psychic is precisely the I and everything which immediately inheres in it. By contrast, when colours are referred to as “subjective”, the value of outer-worldly existents is likewise denied to them; however, one cannot mean by this that colours include in themselves an I, a psychic ego, but one can mean only that colours exist only as objects for a sensing subject. But in this sense, the word “subjective” absolutely does not mean the same as the word “psychic”. For “being psychic” does not mean: existing only as an object for a psychic subject; it is absolutely not something characteristic of what is psychic to be an object for a cognizing I. Thus, what is epistemologically subjective is for this reason far from being something psychic.

Reinach similarly distinguishes between (1) the subjectivity vs. physicality of colours, and (2) the “subjectivity” vs. “objectivity” of colours (Einleitung in die Philosophie, 378–9). In other words, the first sense of “subjective” identified by Pfänder is opposed by Reinach to what is “physical”, whereas the second sense is opposed to what is mind-independent or “objective”. This is in line with what Pfänder and also Geiger say.

Reinach denies that colours are subjective in the sense of being psychic, though he does acknowledge that it might be that they are subjective in the sense of being mind-dependent. But such a mind-dependence would say nothing about the nature of colours; that is, being mind-dependent would not change the essence of colours. In fact, the mistake that must be avoided is to infer from something being subjective in the sense of being mind-dependent that it is subjective in the sense of being psychic. It is not because a physical object does not exist in the outer world that it changes its nature, or essence, and goes from being physical to being psychic.

Note that early phenomenologists have complex theories of essences, and they can mean different things when speaking of an “essence”. What Reinach means by “essence” is a bundle of repeatable properties that are definitional for something, that is, the properties that warrant the (generic or specific) identity of that thing and the loss of any of which would make the thing disappear. Regarding an “essence” understood in this sense, Reinach sometimes speaks of a “what-essentiality” (Reinach, Die Vieldeutigkeit des Wesensbegriffs, from 1912 [1989b]; for more on this sense of “essence”, see Pöll’s, 1936 Wesen und Wesenserkenntnis, 61 and 139–40). What an essence in general requires in this tradition, however, is the ability to be instantiated, which means that there are no essences for impossible objects (following Husserl’s Logische Untersuchungen, 6, § 29, first published in 1901 [1984]); this will become important for the discussion further on.

As already noted, for Reinach, the existence or non-existence of something in the outer world does not affect the nature, or essence, of that thing. This holds for all physical objects, as Reinach emphasises, including colours. Let us see how Reinach explains this (Einleitung in die Philosophie, 378; my addition):

One says however: colour is dependent on consciousness. But even here it does not become psychic. It is psychic once I turn myself towards the colour. For an entity to be physical or psychic depends on its natural constitution; existence has nothing to do with it. Similarly, with the non-existence of objectualities of the outer world these can never become states of the I. Hallucinated physical objects do not become psychic due to the fact that they do not exist.

Here is how I understand this passage: Colours are essentially physical entities; those we experience might not exist in the outer world and might instead be mere appearances correlated to our sensation; in this sense, they would be “subjective” (mind-dependent); but this would not change anything about the essence of colours, including those we experience, for our experience of colours is of physical (though non-existent) entities. In particular, though colours do not exist, they do not therefore become mental acts or states, that is, properties of an ego. Compare the case of colours with that of a hallucinated building (Reinach’s own example in his 1914 [1989e] Über Phänomenologie, 534): a hallucinated building is a mere appearance, that is, it is “subjective” (mind-dependent), but this changes nothing about the essence of the building, in the sense that when we are hallucinating it we are still thinking of a physical object (albeit a non-existent one).

Let me now sum up the view and present it more systematically. According to Reinach, “subjective” has two meanings, each of which has a specific opposite and is best understood when contrasted with it. According to the first sense, “subjective” means psychic: it refers to all egos or subjectivities, for example, me, and their properties, and thus includes all mental acts and states, for example, a feeling of joy. The opposite of “psychic” in this sense is physical, and it includes all extended objects, for example, a building, and their (extended) properties, for example, the shape of the building. Importantly, this distinction sorts kinds of things, that is, it is a distinction about the nature, or essence of things. According to the second sense, “subjective” means mind-dependent; in this sense, it is to be contrasted with “objective”, understood as mind-independent. What is subjective in this sense is everything that exists merely as thought-of, for example, a hallucinated building or an imagined feeling of joy. By contrast, what is objective is that which exists mind-independently, such as a building in reality or a real feeling of joy. Importantly, one and the same kind of thing can be either “subjective” or “objective”, for example a building or a feeling of joy. This distinction is thus not about kinds of things, and does not distinguish natures or essences, but it is about the being, or existence, of things.

Here is an overview of the distinction:

The two senses of “subjective”:

1. subjective (= psychic) vs. physical

  e.g. psychic: me, my current feeling of joy

     physical: a building, its shape

  distinction about the nature, or essence, of things

2. subjective (= mind-dependent) vs. objective (mind-independent)

  e.g. subjective: hallucinated building, imagined feeling of joy

     objective: building in reality, real feeling of joy

  distinction about the being, or existence, of things

If one wants to apply these distinctions to colours, and ask whether colours are subjective or not according to their nature, then the question is about the first sense of “subjective”, for it is this sense which serves to distinguish between kinds of things, that is, the nature or essence of things. Reinach’s reply is then that colours are physical, not psychic, for they are extended entities, and not properties of an ego or a subject. If one takes “subjective” in the second sense, that is, as “mind-dependent”, then it might apply to colours; however – and this is the gist of the position – this would say nothing about their essence, but only about their existence in the world. That is, colours would remain non-subjective with respect to their essence, despite being non-existent.Footnote 7

The view is based on a basic assumption, widespread in phenomenology at least since Husserl’s Logical Investigations (see LU 5, § 11), namely, that we can think of objects of any kind or “essence” without regard to whether they exist or not. In particular, their non-existence does not make of them objects of another kind. For example, I can think of chairs, both existent and non-existent; when I think of non-existent chairs, I am still thinking of chairs, not of things of another kind, or of another nature or essence. What holds for chairs also holds for colours. It might be that the world around us is in fact not a world filled with colours: that is, it might be that philosophers and cognitive scientists denying the reality of colours are right about what happens on the side of existence. However, this would change nothing about the nature of colours: colours, according to their essence, are extended, and as such are physical entities. In short, the non-existence of colours does not affect their essence, and claiming the opposite would be a mistake, as Reinach aptly warns (Über Phänomenologie, 534):

We are assured that colours and sounds are not real, thus subjective and psychic; but these are only obscure words. Let us put aside the reality of colours and sounds – let us agree that they are unreal; do they thereby become something psychic? Can one misunderstand so much the difference between essence and existence that one conflates the denial of existence with a change in the essence, in the essential constitution?

Let me now address a more general issue related to Reinach’s philosophy. Reinach seems to have a clear idea of what the nature or essence of colours is, while (possibly) denying them existence. It even seems that he accepts essences for colours despite the presumed non-existence of such entities in the world. All this sounds very much like Platonism. So is Reinach a Platonist? The answer is clearly yes: early phenomenologists, including Reinach, willingly describe themselves as Platonists (phenomenology is a “return to Plato”, as Reinach says in his Einführung in die Philosophie, 441), and they accept essences as “ideal” (i.e., atemporal) objects. In this respect, they claim that colours have essences independently of their existence or non-existence (beyond Reinach, see, among others, Brunswig, 1914 Das Grundproblem Kants, 142–3). The point is that whether colours exist or not, we do in fact encounter in our visual experience these specific properties and the different features they exhibit, and this is enough for us to get access to their essence. Note that Reinach thinks that we have a genuine acquaintance with essences, a specific sort of intuitive contact. This acquaintance should be distinguished from our intuitive contact with individual phenomena of colours in our visual experience: the intuition of the essence of colours and the sensory intuition of colours are different kinds of mental act (Über Phänomenologie, 532 and 543). Moreover, Reinach is clear that an essence does not itself have the properties that its instances have in virtue of it; for example, the “general triangle”, Reinach says (while discussing Locke), is not itself a triangle (see his 1911 [1989a] Die obersten Regeln der Vernunftschlüsse bei Kant, 64–65).Footnote 8 In any case, Reinach’s view on colours depends on the more general assumption of Platonism, a view defended also by many others, both in the history of philosophy and in contemporary philosophy (see Orilia and Paolini Paoletti 2020 for references to Platonism, including in contemporary philosophy).

However, I do not think that Platonism is required in order to retain Reinach’s main idea. What is useful for him in Platonism is that he can claim to know the nature of colours independently of their existence, by grasping their (Platonic) essence. But even if one is reluctant to adopt Platonism, one can still make claims about the nature of colours independently of their existence. An alternative way open to philosophers for acquiring knowledge about the nature of entities without committing themselves to their existence is conceptual analysis. For colours, the view would run as follows: We encounter in our visual experience specific properties that we call “colours”, which exhibit features that are not those of psychic entities, but rather of physical ones, starting with extension. Thanks to our experience of colours, we then acquire concepts of colours. This is all independent of the existence of colours: even if colours do not exist, it is simply a fact that we have a visual experience of them and build concepts of them. Once we have these concepts, we can analyse them and get to know truths about the properties they are the concepts of – for example, that colours are extended and, thus, physical. The fact that these concepts are empty – that is, that colours do not exist – does not change their possible extension: if there are colours, they fall under the concept of colours, which is a concept of physical entities.Footnote 9 While this view might entail fewer ontological commitments than Platonism, it also has disadvantages, one being that concepts (if one is not a Platonist) are subjective entities, and so it might be unclear in what sense the knowledge we acquire by analysing them is about any “nature”: it might be that our concepts of colours forbid us to think of them as non-extended, but that the nature of colours themselves does in fact allow for non-extended colours. This kind of objection, however, is to conceptual analysis in general, and not to its application to colours. So I leave it open as to whether this option is better than Reinach’s Platonism in the present case.

2.2 Primitivism

Reinach treats colours as “physical” entities. But does he mean that they are “physical” in a physicalist sense? That is, are colours “micro-structural properties” of things, for example, types of dispositions to reflect light, as many physicalist philosophers nowadays argue (see Maund, 2018)? No: interestingly, according to Reinach, colours are primitive entities: they are – to borrow a contemporary description of primitivism – “sui generis, simple, qualitative, sensuous, intrinsic, irreducible properties” (Maund, 2018). In short, they are the properties that we get acquainted with pre-theoretically in our visual experience: yellow, red, blue, etc.

Note an important point: primitivism is about the nature of colours, not their existence. It is thus compatible with eliminativism, and is often combined with it in contemporary literature (see Byrne & Hilbert, 2007 and Maund, 2018). In fact, primitivists identify a specific kind of property in our experience, namely, what we usually call “colours”, and accept that it is sui generis and irreducible; they then look at the results of physics and try to see whether these entities are found somewhere there; but since physicists do not include these entities in their description of reality, and since physicists are those we should believe when we want to know what reality is ultimately made of, then colours should be eliminated from our picture of reality. In short, being a primitivist about colours does not mean being a naive realist: you can be both a primitivist and an eliminativist. Reinach would aptly say that primitivism is a thesis about the nature or essence of colours, while eliminativism is a thesis about their existence; hence, the two positions are compatible.Footnote 10

One path towards primitivism in contemporary philosophy is the thesis called “revelation”, which has been much developed by Johnston, and which holds that “the intrinsic nature of [colours] is fully revealed by a standard visual experience as of [colours]” (1992: 223). Now, some contemporary philosophers argue that revelation leads to primitivism (see Byrne & Hilbert, 2007): our experience is supposed to “reveal” to us the nature of colour, and what is “revealed” to us is something primitive, namely, colour. Thus, on this view, when I have an experience of colour, I am facing a very specific kind of property, which presents itself to me as distinct from everything else I know (sound, shape, artistic beauty, etc.). If this acquaintance with colours as specific properties is supposed to reveal to me the nature of colours, then colours are primitive entities.

A view very similar to revelation was defended by some of the early phenomenologists. For example, Pfänder (Einführung in die Psychologie, 280) writes as follows:

[…] many humans hear sounds and see colours, that is, have a specific immediate knowledge of sounds and colours, without knowing anything here of vibrations of the air or electric vibrations, that is, of stimuli.

One can reasonably draw from this quote that Pfänder is a primitivist about colours, given his apparent commitment to revelation. The combination of revelation and primitivism is argued for more explicitly by Reinach. But since he is defending Platonism about the essences of colours, Reinach reframes the talk of revelation and primitivism in a Platonic way (Über Phänomenologie, 534):

When the physicist reduces (zurückführen) colours and sounds to vibrations of a certain type, he is directed towards real existences, whose factuality he wants to explain. Let us put aside the deepest sense of reduction – it certainly finds no application with respect to essentialities. Or would one perhaps like to reduce the essence of redness, which I can contemplate in each case of redness, to the essence of vibrations, which is obviously different?

According to Reinach, revelation and primitivism are ultimately about Platonic essences. The nature of colours is revealed to me in my ordinary experience of colours, in the sense that my sensory intuition of a colour phenomenon leads me to an intuition of the essence corresponding to the phenomenon in question. Thus, what is revealed to me is a Platonic essence, and the fact that colours are not reducible to anything else, for example to vibrations, is explained by the brute fact that the essence of colours is distinct from that of vibrations. This allows for an ontological grounding of the irreducibility thesis independently of whether colours exist in the world. Note that this irreducibility still allows for a “reduction,” or elimination, with respect to the existence of colours, as the beginning of the text says, for this is a question about their existence. That is, it might be that colours do not exist in our world, but only vibrations do, something that the physicist should be able to prove to us; however, this would not change anything about the irreducibility at the level of the nature of colours.

Reinach’s Platonism gives him an advantage over other philosophers on colours. For when you are both a primitivist and an eliminativist, you claim to grasp the nature of something whose existence you at the same time deny. But if this thing does not exist, how can you have any knowledge about its nature? It seems that your grasp of the nature in question is objectless. Reinach has an answer: when I am acquainted with the nature of colours, there is in fact an object that I am grasping, namely, the essence of colours. Despite the notorious epistemological problems that theories of the “vision of essences” face (see Benacerraf, 1965), it is clear that Platonism has an advantage in being able to explain how one can reasonably combine primitivism and eliminativism, as contemporary philosophers often do (see again Maund, 2018).

Before I come to the discussion of the existence of colours, let me address an important issue. In what I have said so far, I have ruled out Reinach being a physicalist about colours, and claimed that he is a primitivist. Now, among the central positions about the nature of colours in contemporary philosophy, there is one I have not yet addressed, namely, dispositionalism. According to dispositionalism, colours are “dispositions to look a certain way” in sensory subjects, that is, “dispositions of objects to produce a certain experience” (Johnston, 1992: 225). According to some interpreters, dispositionalism is a form of relationalism about colours, needing a subject as the correlate of the disposition, just as solubility requires that there be some water in the world; according to others, dispositionalism is not relational, for dispositions, even those whose description is relational – for example, solubility understood as the disposition to be dissolved in water – are monadic entities from an ontological point of view (see Gow, 2014: 807). If dispositionalism is a form of relationalism, one could then say that it makes colours subjective entities, since to be instantiated they would require a subject as their correlate (provided one accepts the rarely contested claim that a relation needs two relata to be instantiated) (see again Gow, 2014: 807).

Does Reinach take into account this sense of “subjective”? In my opinion, he does not. To begin with, colour as a disposition of an object to produce a certain experience is certainly not a property of an ego, so the first sense of “subjective” is not relevant. Second, a disposition is not subjective in the sense of merely existing as an intentional object. For a disposition does not necessarily cause any experience in a subject, and yet it would have to do so in order to be thought of (and thus be an intentional object); it is enough that there is a subject in which it could cause an experience (just as solubility requires that there be water in the world, not that the soluble thing is actually dissolving). Interestingly, this shows that there is a third sense of “subjective” that could be relevant in discussions about colours, namely, something being subjective in the sense of needing a subject to exercise its effect. This point is not considered by Reinach.

Independently of this question, however, I think that Reinach would deny that colours are dispositions to produce appearances in us. I suspect that he would adopt a classic argument against dispositionalism, namely, that colours, as is clear from our experience of them, are occurrent properties of things, not mere dispositions to produce an effect. In other words, dispositionalism contradicts the nature of the properties we encounter in our visual experience and call “colours”, but it is the nature of colours that we want to elucidate, not that of something else (for a rejection of arguments in the style of the one I attribute to Reinach and for a defence of dispositionalism’s compatibility with our common-sense beliefs about colours, see Maund, 2018 and his presentation of Levin, 2000).

3 The existence of colours

3.1 Criticism of arguments against realism

We have seen so far the following: For Reinach, colours are not subjective according to their essence; they might be subjective regarding their existence, but this is another sense of “subjective”. For in the first sense, “subjective” means psychic, and it is opposed to what is physical; this is a distinction about the nature, or essence, of things. According to this distinction, colours are physical properties, and even primitive ones. In a second sense, however, “subjective” means mind-dependent, and this is opposed to objective, or mind-independent; this is a distinction about the being, or existence, of things. As I have shown, Reinach holds that the colours around us are perhaps mind-dependent, but colours nonetheless are essentially physical, regardless of their existence or non-existence.

I would now like to ask whether, in addition to being essentially non-subjective, colours for Reinach are also existentially non-subjective, that is, mind-independent. In fact, the solutions given by early phenomenologists to this question are divergent. Some of these authors are naive realists, for example, Maximilian Beck (see his 1925 Wert und Wesen, 77–80); others deny the existence of colours, for example Paul Linke (in his 1929 Grundfragen der Wahrnehmungslehre, 168). Note that those who both claim that colours are physical entities and deny their existence, such as Linke (see Grundfragen der Wahrnehmungslehre, 128–32),Footnote 11 anticipate the contempo­rary view called irrealist representationalism, according to which what we represent in our sensory experience of colours are not subjective properties but properties of physical things, even though these properties do not exist. Interestingly representationalism is often combined with Platonism about colours, just as is the case in the early phenomenologists (e.g., Linke, Grundfragen der Wahrnehmungslehre, 132–4; on irrealist representationalism, see Pautz, 2006).

But there is one member of the tradition who remains neutral about the existence of colours, namely, Reinach. He criticises several arguments for non-realism about colours. While this might give the impression that he defends realism, in fact he claims not to know how to settle the existence question. In other words, he does not take a position on the question: there are essences of colours, Reinach says, but we do not know whether they are instantiated around us, that is, in our world. I suggest that we call his view ontic-neutral essentialism. In what follows, I will first present Reinach’s arguments against non-realism (found in Einleitung in die Philosophie, 379–380), and then draw some interesting consequences of his ontic-neutral essentialism.

The first argument against realism that Reinach discusses is about interpersonal variation in colour perception (for a detailed discussion of this argument in contemporary philosophy, see Allen, 2016: 50–7). According to this argument, colours cannot exist, since different people see different colours in the same place. Reinach’s reply is straightforward: this is an epistemic problem, not a metaphysical one (Einleitung in die Philosophie, 379). (Note that the same strategy is used against similar arguments in contemporary philosophy as well. See, e.g., Byrne & Hilbert, 2007.) This might create the further worry that the decision of which colour is the correct one seems arbitrary, but such a worry still does not allow one to draw a metaphysical conclusion from epistemic indecision (see again Byrne & Hilbert, 2007, whom I follow on these issues). Another reply might be that things do in fact have several colours, a view known as colour pluralism, which is defended by both naive realists and physicalists in contemporary philosophy (Kalderon, 2007; Mizrahi, 2006). However, Reinach does not take this path.

The second argument against realism is about the violation of the transitivity of identity. For among three shades of colour, we might, despite all our efforts to discriminate things clearly, judge that shade 1 and 2 are the same, that shade 2 and 3 are the same, but that shade 1 and 3 are not the same. This is of course a problematic outcome, since it violates the transitivity of identity. One way to solve the problem would be to say simply that colours do not exist, and so there are no things in the first place that could be identified. Reinach has another solution. His reply, again, is that this might simply be an epistemic issue: colours as they appear to us and as they exist are different. Or, he adds, this might show that colours are vague; that is, it is impossible to measure them exactly, and so there will always be cases in which non-identical colours are indiscernible. But, Reinach adds, non-measurability does not exclude existence (Einleitung in die Philosophie, 379). This suggests that he is in favour of ontic vagueness about colours, for his point seems to be that if colours do exist they are vague (and vagueness is not a reason to deny that they exist). (For discussion of vagueness and the “non-transitivity of indiscernibility” in contemporary philosophy, see Egré 2008: 59–61, whom I follow for the theoretical aspects of my reconstruction. Note that Reinach’s example is about sounds, but I adapt the argument to colours, following an example given by Husserl in a manuscript from 1925 [2012: 152]. For a similar discussion about Husserl, see Taieb 2022: 132.)

A third argument is one from scientific authority. The argument is simply that science rejects the existence of colours. Reinach’s reply is that this is wrong, for in botany and zoology colours are treated as real, for they are used in various inquiries and classifications. But what about physics, one will surely ask? Reinach’s answer is that physics neglects colours in its understanding of the world, but this does not mean that it rejects their existence; they simply have no explanatory role at the “mechanical” level of physics (Einleitung in die Philosophie, 379–380; see also his 1913 [1989c] Über Dingfarbe und Dingfärbung, 367).

Does this rule out colours having any kind of causality? Contemporary philosophy, in particular naive realism about colours, might be of some help here in order to see what theoretical options Reinach has at his disposal. As a rule, naive realists attribute some causality to colours, the assumption being that causally non-efficacious entities seem to be too spooky to count as real. At the same time, naive realists accept that efficient causation in colour vision is due to some subperceptual physical entities, for example, reflectance properties. So the kind of causation they attribute to colours cannot be efficient, for this would lead to causal overdetermination. The idea, then, is to say that the causal import of colour is that of constitution: colours are causes in the sense that they are metaphysical constituents of perception (Allen, 2016).

Is this path open to Reinach? It might be, but with a qualification: usually, the thesis that objects are constituents of perception is defended by disjunctivists, for whom perception and hallucination are toto genere distinct kinds of mental acts (this is the case in Allen, 2016, for example). Reinach, by contrast, is not a disjunctivist, for he states that “hallucinations after all are perceptions as much as any other ones” (Einleitung in die Philosophie, 374). However, this would not forbid him from saying that colours are constituents of correct perceptions. He seems to suggest something like this when he claims, in a passage where he is discussing perception, that it is “not a contradiction that the house is in consciousness and at the same time has a proper real existence” (Einleitung in die Philosophie, 382). If Reinach were a realist about colours and if he were to deny that colours have any causal power, then he could certainly be labelled an “epiphenomenalist” or a “weak emergentist” about colours (for weak emergentism as denying proper causal powers to emergent entities, in contrast to strong emergentism, see O’Connor, 2020).

The last argument against realism about colours, which Reinach also rejects, is about the correlation of colours with our sensory organs, more precisely, the eyes. The argument is that colours have no mind-independent existence, but they do depend on our visual system; for we are acquainted with them only with our eyes, just as we hear sounds only with our ears, and similarly for other sensory qualities and their corresponding sense organs. Reinach’s reply is that our senses allow us to grasp these properties, but this in no way means that these properties do not exist. On the contrary, we have the right apparatus to grasp them: for example, we have eyes, thanks to which we can see colours (Einleitung in die Philosophie, 380).

3.2 Ontic-neutral essentialism

But does Reinach adopt realism? The answer is no. After presenting all these arguments, Reinach makes the following claim (Einleitung in die Philosophie, 380): “The question of the subjectivity or objectivity of sensory qualities, however, is not yet in a solvable condition. Philosophy is not mature enough to decide about the question.” In other words, he adopts a neutral view: we know about the essence of colours, but we are not sure about their existence in the world.

Note an important point: for Reinach, just as for other early phenomenologists, colours as essences exist, namely, as ideal entities; the neutral stance is about the existence of instances of colours. So what Reinach is not sure about is whether there are instances of colours. Since he accepts essences of colours, however, he also thinks that colours could be instantiated, for as noted above, impossible objects do not have essences in early phenomenology. In other words, (instances of) colours could possibly exist.

In fact, what early phenomenologists say is that the question whether instances of colours exist or not in the world is an empirical question. As Linke holds (Grundfragen der Wahrnehmungslehre, 168), “empirical science” has proven the “fact” that colours do not exist. While Reinach does not want to go as far as Linke in endorsing empirical non-realism, he does clearly reject another sort of non-realism, which I will call “metaphysical non-realism”; according to this view, colours could never exist, in any (possible) world. As noted above, by accepting essences of colours, Reinach also accepts that colours could indeed exist.

Interestingly, these considerations show that the debate about the existence of colours might need to be refined: one should in fact distinguish between empirical non-realism, which claims that there are no colours in our world, and metaphysical non-realism, which is the much stronger claim that the existence of colours is ruled out in any (possible) world. To my knowledge, this distinction is generally not addressed in the contemporary literature on colours; one exception is Chalmers (2006: 79–80), who wonders whether “Eden” – that is, the place where there is a perfect qualitative fit between the content of our experience of colours and reality – is metaphysically possible or not. But even in Chalmers, the question of realism about colours is not clearly distinguished along empirical vs. metaphysical lines. It is not clear, then, whether non-realists about colours in contemporary discussions mean that there are no colours around us but that there could be colours in the absolute, or whether they mean that there could not be colours at all in our world or in any (possible) world. But being clear about this question is crucial for the debate in the metaphysics of colours, for it means being clear about the scope of the denial of their existence.

I think that the Platonic ontic-neutral essentialism about colours defended by Reinach helps us to become aware of this point. For on the one hand, Reinach posits essences of colours, which means that colours could be instantiated; on the other hand, he says that he does not know whether these essences are instantiated in the world around us. This means that he does not want to decide about empirical realism or non-realism about colours. However, he does reject another form of non-realism, namely, the claim that colours could never exist, or metaphysical non-realism.

As briefly noted above, I think that the distinction between empirical and metaphysical non-realism about colours is important and philosophically valuable. I would like to present a few general considerations about its theoretical relevance. First, it raises interesting metaphilosophical questions. It is often argued that philosophy is not an empirical science. The non-empirical nature of philosophy can be understood in different ways, but the main idea is roughly that philosophy is not interested in truths about matters of fact, but in a priori truths. The inquiry about a priori truths has itself been understood in different ways throughout the history of philosophy: as contemplation of essences (in the Platonic tradition), as truths about ideas (in early modern philosophy), or as conceptual analysis (in analytic philosophy). Now, if it is correct that the inquiry about the existence of colours divides into an empirical question (“Do colours exist in our world?”) and a metaphysical one (“Can something like colours exist in the first place?”), one faces a dilemma. On the one hand, if philosophy is supposed to be about non-empirical truths, then one should exclude from philosophy any discussion of the existence of colours in our world. What philosophers interested in theories of colours should do instead is to focus on the question of whether colours can possibly be instantiated. This is what Linke hints at when he says that the non-existence of colours has been proved to us by “empirical science” (Grundfragen der Wahrnehmungslehre, 168): he seems to imply that this is not a topic for philosophers. On the other hand, if one thinks that the question whether colours exist in our world is a genuine philosophical question, then one should accept that philosophy is (at least partially) an empirical discipline. If one takes this second path, however, then this should lead one to ask oneself exactly what kinds of empirical questions are to be included in philosophy and why some are to be included and not others.

Second, the distinction between empirical and metaphysical non-realism about colours should help philosophers to delimit more sharply the scope of their claims about colours and also the adequacy of the arguments that they use to support these claims. Defending the view that colours do not exist in our world or that they cannot exist at all are claims with different scopes, and defending each of these claims would require different kinds of arguments. In fact, arguments against realism about colours have themselves either an empirical or a metaphysical scope. Presumably arguments based on colour science, which rely on our physiology, might aptly deny empirical realism about colours, but not metaphysical realism. For example, the theory of specific nerve energies was used as an argument against realism about colours. The idea is that our different nerves each produce a specific appearance when they are stimulated, and crucially, this is so whether they are stimulated peripherally or in some other way. In other words, the stimulation of our visual nerves always produces vision of colours, even if it is not stimulated peripherally through stimulation of our eyes, but elsewhere on the nervous circuit. This makes it plausible that the appearances of colours is simply an endogenic result of the stimulation of our nerves rather than the result of something like colours existing outside and causing seeing of them in us (on this argument, see Stumpf’s posthumous 1939–1940Erkenntnislehre, 586). This argument is based on empirical issues about our physiology and allows for empirical claims about the non-existence of colours in our world, but presumably not about the non-existence of colours in general: it does not show that it is absurd to think that something like colours could exist.

Similarly, another argument against realism about colours, already mentioned, says that since different human beings might see different colours on the same surface, it is implausible that these appearances are caused by something outside, for it would be arbitrary to choose one colour in the series as being the correct one (see the reference to Allen, 2016 above). Here again, an empirical fact about colour vision can be used to deny the empirical existence of colours in our world, but this cannot be easily used to defend metaphysical non-realism.

Other arguments found in the literature seem rather to support metaphysical anti-realism. For example, Byrne and Hilbert think that colours, if they were to exist, would have to supervene on a physical basis. They go through several supervenience scenarios, including in other possible worlds, and show that they all lead to absurd consequences. (I cannot reconstruct their sophisticated argumentation here; for more detail, see Byrne & Hilbert, 2007.) This kind of argument, based on philosophical material such as supervenience theories and possible-worlds hypotheses, and not on colour science, can seemingly be used to try to refute the existence of colours not just in our world, but in any possible world.

This shows that philosophers interested in realism about colours should first ask themselves: “What exactly do I want to deny: that colours do not exist in our world, or that colours could not exist at all?” and, second, they should look at the correct arguments in favour of their claims. In particular, an argument against empirical realism would not be of great help for someone who wants to argue that colours could not exist at all. One should be careful to have a good fit between the scope of one’s claims and the scope of one’s arguments. These interesting consequences should of course be explored further. This cannot be done in the present paper, but I hope that the previous paragraphs have shown how relevant, at both the metaphilosophical and argumentative levels, the distinction drawn from Reinach between empirical and metaphysical non-realism about colours can be.

Note that these issues might also be the reason why Reinach says that philosophy is not “mature enough” to address the question of the objectivity of colours. Philosophers should first be clear about what they want to determine when they ask whether colours exist: do they mean their existence in our world, or in any possible world? If they mean the first alternative, they then have to decide whether philosophy should address empirical problems, and if so why that of colours and not other problems. Finally, when addressing the question of the existence of colours, philosophers should take care to select, among the available arguments pro or contra colours, those that best suit their purpose, that is, whether they are arguing for empirical or metaphysical (non-)realism. In short, there is a lot to consider before entering into discussion about the existence of colours.

4 Conclusion

For Reinach, while colours might be subjective existentially, and thus do not exist in the outer world, they remain essentially non-subjective, that is, non-psychic. According to their very essence, colours are physical. This view is based on a distinction that Reinach makes between two senses of “subjective” which are usually conflated, leading us to (wrongly) infer from the non-existence of colours that they must be psychic. What Reinach helps us to see is that if we find ourselves resistant to the subjectivist thesis that colours are subjective properties, this may be because it can be taken to be employing “subjective” in the sense of being psychic, which would be erroneous: colours are extended, and so are not psychic entities, but physical ones. These distinctions make it clear in which sense subjectivism about colours should be understood. If subjectivism is to be a plausible philosophical thesis, it has to be understood as opposing the subjectivity of colours to their objectivity, not to their physicality, and as making claims about the existence of colours, not about their essence. For according to their essence, colours are physical.

Another interesting aspect of Reinach’s view is that it allows us to see that our debates about realism and non-realism about colours are not well delimited, for it is not clear whether those who defend realism or non-realism mean that colours do not exist in our world or whether they mean that colours could not exist in any (possible) world. Ultimately, this comes down to the question of whether non-realism about colours is understood as an empirical thesis or as a metaphysical one. This needs to be clearly decided in the discussions about colours in order to get a correct grasp of the scope of the inquiry. This point becomes salient when one reads Reinach, for he posits essences of colours, which entails that there could be instances of colours, yet also adds that he does not know whether they are instantiated around us, which leads us to see that one has to distinguish between the non-existence of colours in our world and their non-existence absolutely, that is, between empirical and metaphysical non-realism. This conclusion is, in my opinion, an important result we get from considering Reinach on the essence of colours.