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Peter Reynaert

Does Naturalism Commit a Category Mistake?

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For Ryle dualism commits a category-mistake. Contrary to Ryle, but without endorsing dualism, I argue that naturalism risks committing a category-mistake. Husserl formulated laws of meaning to distinguish nonsense from absurdity. Formally absurd expressions violate formal, logical laws. Material absurdity results from the particular material concepts employed. Identifying material absurdity requires knowledge of the nature of the entities the expression is about. Correlated with the categories of meanings are ontological categories, both formal and material. Material categories or essences, which Husserl calls ‘regions’, classify entities according to their nature or essence, knowledge of which is based on ideative abstraction. Science must respect in its conceptual framework the ontology of its subject. When a regional being is explained by concepts that cannot be applied to it, a fundamental problem arises, which Husserl calls a metabasis eis allo genos, in Ryle’s terms a category-mistake. Husserl’s analysis of the lived body (Leib) illustrates the absurdity of the naturalistic explanation of human existence. Reducing the Leib to a Körper is a category-mistake, creating material absurdity. The naturalist understands the object to be studied (Leib) with notions that belong to another ontological region, namely physical nature. The Mind-Body problem is the result of this category-mistake.


1Ryle famously argued in The Concept of Mind that dualism commits a category mistake. A category mistake “represents the facts (…) as if they belonged to one logical type or category (or range of types or categories), when they actually belong to another.” (Ryle 1990: 17) As is well known, for Ryle the doctrine of “the ghost in the machine” or dualism is the result of the idea that the mind belongs to the same category as the body. “Minds are things, but different sort of things from bodies” (Ryle 1990: 20). This category mistake leads to all kinds of absurdities in theorizing and explaining when the two presumed entities are causally related. In his book, Ryle wants “to prove that the official theory does rest on a batch of category-mistakes by showing that logically absurd corollaries follow from it” (Ryle 1990: 24). By exposing this mistake, he perhaps inadvertently condoned the naturalistic analysis of the mind in 20th century analytic philosophy.1

2Contrary to Ryle, but without returning to dualism, I want to argue that naturalism itself could be identified as committing a category mistake in its interpretation of human existence. I refer to Husserl in order to substantiate my claim that naturalism is an absurd theory. First, I will explain Husserl’s notion of absurdity, which he distinguishes from sense and nonsense. In itself, this is already an interesting approach, since the more familiar distinction of sense and nonsense, as we know it from logical positivism, was here earlier completed with a proper notion of absurdity.2 Positivism later collapsed absurdity with nonsense and thereby lost an important diagnostic tool for distinguishing various sorts of (il)legitimate speech. This is due to its empiricist epistemology. Second, after having clarified what naturalism is according to Husserl, I will explain that naturalism is absurd according to him because it commits what he calls a metabasis eis allo genos (a change to another genus). I will illustrate how this applies to naturalism’s analysis of embodiment. Third, I will signal a potential problem with his approach, more precisely concerning the possibility of a priori knowledge of ontological categories, on which the identification of the category mistake of naturalism is founded.

1. Nonsense versus Absurdity

A. Nonsense

3The first question to be answered is what absurdity consists of. In the 4th Logical Investigation Husserl distinguished absurdity from sense and nonsense. He developed an a priori pure logical grammar, which aims at identifying the laws that determine what sorts of expressions can be meaningfully combined (Thomasson 2002: 123). This pure logical grammar has to be distinguished from linguistic grammar, which contains the rules of natural languages. These a priori laws of meaning not only serve to separate sense from nonsense, but also to distinguish nonsense (Unsinn) from absurdity or counter-sense (Widersinn). Nonsense implies a combination of expressions, and hence meanings, from different syntactic categories, and results in meaningless expressions like for instance: “ein rundes oder” (a round or) or “ein Mensch und ist” (a man and is). (Husserl 1984: 334; Husserl 2001, Vol 2: 67)

4In the first example, three so-called syncategorematic expressions are combined. Normally, syncategorematic expressions don’t have an independent meaning of their own, and can only be meaningfully used in combination with a categorematic expression, which has an independent meaning. A noun is an example of such a categorematic expression, and an adjective like “round” only makes sense when combined with a noun. Because it is meaningless, a nonsensical expression does not and cannot refer. No corresponding object can exist:

Husserl’s understanding of ‘nonsense’ is rather strict: he counts only those strings of words that are syntactically incorrect so that they form a mere ‘heap of words’ and cannot be combined into any unified meaning, as strictly nonsensical, and thus as signs of differences in categories of meaning. (Thomasson 2013)

B. Absurdity, formal and material

5For Husserl, absurdity on the contrary is meaningful, it does make sense, but it is nevertheless logically wrong. Because of this, absurd expressions do not refer either. There is no and cannot exist a corresponding object. Husserl distinguishes two kinds of absurdity: formal from material absurdity. Expressions are formally absurd when they violate purely formal, logical laws, like the law of contradiction, of double negation or the modus ponens law. “A round not-round thing” is formally or analytically absurd because it is contradictory. “Expressions are materially absurd if the impossibility of there being a corresponding object is based in the particular material concepts employed.” (Thomasson 2013) “A square is round” or “a wooden iron” are materially absurd expressions because of the particular meanings of ‘round’ and ‘square’ in geometry and of ‘wooden’ and ‘iron’ in physics (Husserl 1984: 334–5; Husserl 2001, Vol 2: 67). Yet, because they are meaningful, their absurdity is much more difficult to recognize. This identification requires knowledge of the nature of the entities the expression is about, in this case geometrical and physical knowledge.So actually, long before Carnap and others agreed that there may exist meaningful expressions which are nonetheless devoid of cognitive significance, Husserl developed the same point. Yet where Carnap considers them to be nonsensical, Husserl calls them absurd, and he insists that it is necessary to distinguish the two.3

2. Metabasis eis allo genos

6A. Correlated with the categories of meanings are ontological categories, both formal and material. The formal ‘categorial essences’ include, for example: object in general, state of affairs, property, relation, etc. As indicated above, nonsense results when we combine syntactical categories in the wrong way, and this now means that we also have mistakenly combined different formal ontological categories. Husserl distinguishes these formal ontological categories from the material categories or essences, which he calls ‘regions’. These classify entities according to their nature or essence. Hence regions are material a priori separate fields (sachhaltig apriorische Sondergebiete) (Husserl 1974: 158; Husserl 1969: 150; Husserl 1985: 435). A material ontology explicates the most general or generic properties of a regional being or genus. Physical nature for instance has as the highest generic properties temporality, spatiality, causality and materiality, which together constitute its reality. (Husserl 1952: 41–5; Husserl 1989: 44–9)4 The psyche lacks this materiality and spatiality and is thus according to Husserl a non-material causal reality, whose psychological processes are caused by and in turn cause bodily processes. A regional being is the object of a specific experience (Husserl 1971, XVIII: 38). For instance, the perception of a material thing differs descriptively from the experience of the psychological life of an animate being. Phenomenological description of this original experience is the basis of material ontology, which identifies the essential (eidetic) ontological structures of a regional being. Arriving at these highest essences is not only based on the description of the experienced object but also on the method of ideative abstraction (ideierende Abstraktion), which founds the specific material ontology of each of the regions (Landgrebe 1963). There are as many ontologies as there are regional concepts (Husserl 1971: 25). Every object with its material (i.e., non-formal) characteristics belongs to a region which can be identified with respect to its essential features.

7The more fundamental material ontology of the world we experience, which Husserl later calls “the ontology of the life-world”, leads to a distinction of the so-called fundamental regions or basic material ontological categories of this world.5 In the second book of his Ideas, Husserl identifies three regions in the world of natural experience: physical nature, animate being and Geist or Spirit (Husserl 1971, XIX).6 Animate being is the name for a living being with a psychological life. Spirit is the overarching term for all instances of human existence. The spiritual world (geistige Welt) contains human beings with their conscious, embodied existence and furthermore the fundamental entities of the human world like for instance language, music, politics but also all other instances of human culture. The use of the word Geist does not have a Hegelian connotation here, but is to be understood in opposition with nature, as is clear from the debate about the specificity of the Geisteswissenschaften over and against the Naturwissenschaften. Husserl clearly argues against the idea of a unified science and pleads for the methodological specificity of the Geisteswissenschaften for the study of humanity. This specificity is ultimately founded on the ontology of Spirit.

8Scientific analysis and explanation must respect the ontology of their subject, which must be taken into account in the conceptual framework.7 With each different region comes a different set of concepts and thus a different explanation.8 Husserl explicitly states that it is evident that we have to reject every descriptive notion which is excluded by the regional concepts:

(…) the originary sense of the object cannot be annulled by any theory. It is the norm which must be presupposed and to which all possible theoretical cognition is rationally bound. Hereby is designated a universal rule for the fundamental clarification of all regional concepts — thus all concepts which delimit the domain of objects of a regional ontology (and therewith of all special and empirical disciplines of the regional sphere in question) (…). (Husserl1952: 91; Husserl 1989: 97)

9When a scientific discipline explains a regional being by concepts that cannot be applied to it, a fundamental problem arises, a metabasis eis allo genos (a change to another genus) or in Ryle’s terms: a category mistake. The ensuing theory commits what Husserl identified as a material absurdity in his 4thLogical Investigation. He repeats this in Ideas II when he says that not to take into account the essence of the object under study creates Widersinn (Husserl 1952: 91; Husserl 1989: 96). This absurdity is the result of combining different ontological and conceptual categories that should be kept apart, because they refer to distinct ontological regions and entities. It is the task of philosophy as a theory of the a priori to help the sciences to avoid this absurdity, by gaining insight in the sense and essence of scientific method in relation to its object (Husserl 1975: 255; Husserl 2001, Vol.1: 161; Husserl 1974: 10). So the classification and distinction of the sciences is dependent upon this notion of region according to Husserl (Husserl 1971: 25). “Every science of facts (Tatsachenwissenschaft) has essential, theoretical foundations in eidetical ontologies”, as Husserl explains in the first chapter of his Ideas, Book I, entitled “Tatsache und Wesen” (Husserl 1976-1: 23).

10Husserl already identified this mistake in the Prolegomena when he criticized logical psychologism:

There is another, much more dangerous fault in the field-delimitation: the confusion of fields, the mixture of heterogeneous things in an putative field-unity, especially when this rests on a complete misreading of the objects whose investigation is to be the essential aim of the proposed science. Such an unnoticed metabasis eis allo genos can have the most damaging consequences: the setting up of invalid aims, the employment of methods wrong in principle, not commensurate with the discipline’s true objects, the confounding of logical levels so that the genuinely basic propositions and theories are shoved, often in extraordinary disguises, among wholly alien lines of thought, and appear as side-issues or incidental consequences etc. (Husserl 2001, Vol 1: 13; Husserl 1975: 22)

11B. There is material absurdity in the case of the naturalistic interpretation of human existence, and more precisely of consciousness. Before explaining this, it should be remarked that naturalism has a complex meaning for Husserl. A first meaning concerns the falsification of ideal logical norms and laws in terms of inductively found psychological rules concerning the legitimate connection of mental states. This is what psychologism in logic does, as Husserl explains in his Prolegomena. Secondly, in the context of his transcendental phenomenology, he argues that “naturalism essentially misconstrues consciousness by treating it as a part of the world” (Moran 2008: 1). Naturalism is understood here as the basic characteristic of the common natural attitude (natürliche Einstellung), which Husserl opposes to the more fundamental transcendental attitude. As he explains in the Crisis, it is a form of objectivism, which means that it starts from the common belief in the existence of the world, without clarifying its relation to transcendental consciousness. The naturalist does not perform the transcendental reduction. How non-transcendental, mundane or worldly consciousness is analyzed as a part of the world can further be specified, and this leads to a third notion of naturalism. Thirdly, and only this sense matters in the present context, naturalism is characterized by what Husserl calls the naturalistic attitude. This attitude is, together with the personalistic attitude from which it substantially differs, based in the common natural attitude. It is foundational for what we now call physicalism, whereas the personalistic attitude founds the hermeneutical approach typical for the so-called Geisteswissenschaften. So it makes sense to distinguish between a naturalism in a broad sense, characterized by the “natürliche Einstellung”, as opposed to transcendentalism, and naturalism in a more narrow sense. The latter defines itself by the more specific “naturalistische Einstellung”, which is opposed to the personalistic attitude, and it gives rise to physicalism with regard to man (Husserl: 1952: 13942; Husserl 1989: 14750).9 Given these distinctions, even the non-naturalistic Geisteswissenschaftler is a naturalist in the first broad sense.

12As Husserl remarks about ‘narrow’ naturalism in Philosophy as Rigorous Science:

Hence the naturalist (…) sees nothing but nature and first and foremost physical nature. Everything that is is either itself physical, belonging to the unitary nexus of physical nature, or it is indeed something psychical, but then a variable that merely depends on the physical, at best a secondary, “parallel accompanying fact”. All beings are of a psychophysical nature, that is, univocally determined in accordance with firm laws. (Husserl 2002:253–4)

13This naturalistic approach considers physical nature as the basis of everything there is and adopts the methods of the sciences to causally explain reality. In modern terms one could say that we are confronted here with both ontological and methodological naturalism (Papineau 2009). Of course, Husserl is well aware of the fact that there exist what he calls psychophysical dependencies or conditionalities. In Ideas II and III he explains that our perceptual processes are causally related to our body. If you consider perception to be a psychological activity, then the psyche is a non-material reality, causally determined by bodily processes. Husserl speaks here of somatological causality, which concerns the relation between a subjective perceptual event and the body (Husserl 1952: 65; Husserl 1989: 70).10 In that sense, a naturalistic approach of man has obvious validity. But it also encounters serious explanatory difficulties already at this basic level of human existence.

14C. One can illustrate this diagnosis with reference to Husserl’s analysis of the lived body (Leib), which is primarily characterized by its sensitiveness (Empfindsamkeit). (Husserl 1952: 155; Husserl 1989: 163). The naturalist understands the object to be studied (Leib) with notions that belong to a particular ontological region, namely physical nature (Körper). The result is a misidentification of the Leib’s basic properties such as, for example, its crucial sensitiveness. Sensitiveness is for the naturalist a non-physical, psychological property of the organism that has to be explained by the organic, bio-chemical and neurological mechanisms underlying it. He wants a physio-psychological causal explanation. Husserl only partly agrees because he accuses naturalism of absurdity, but one has to be careful to understand what this disagreement is precisely about. Sensitiveness certainly is a non-physical, psychological property of the Leib. Tactile sensitiveness for instance does not constitute another physical property of the hand like its roughness or smoothness (Husserl 1952: 145–6; Husserl 1989: 152). And no other material object besides an appropriate living organism is sensitive. It is also true that our sensitiveness is conditioned by bodily processes, when the body has causal relations with other external objects and is influenced by physical circumstances. “The Leib, we can say, always has states of sensation, and which particular ones it has depends on the concomitant system of real circumstances under which it senses.” (Husserl 1952: 155; Husserl 1989: 162) The body as a sensitive organism is stimulatable (reizbar) which means that physiological changes in its perceptual organs occur as the result of causal contact with external objects or circumstances. Changing sensitiveness is the result of this dependency or conditionality and hence a psychophysical property. Sensations are consequences of stimuli (Reizerfolge). So far, a naturalistic search for causal mechanisms is no problem.

15But the occurrence of physical stimuli and the changes they undergo do not explain the presence of our sensations. Sensations are more than physical stimuli, they are experiences. Husserl distinguishes stimulatability (Reizbarkeit) from sensitiveness (Empfindsamkeit) and stimuli from sensations. The first concern the body as a physical organism, the second concern the lived body or Leib, more precisely the subjective experience of embodiment. The body is not only covered by the skin which contains receptors that can be stimulated by physical contact, the skin is also a field of sensations (of touch, etc.) (Husserl 1952: 154; Husserl 1989: 161). When we enter a hot room, not only our heat sensors are activated, we also have a change in the sensation field that we call heat sensation and we consequently feel warm. But this is only true if the body is already subjectively experienced. It must be this physical and aesthesiological unity, and hence a Leib, for physical stimuli to be experienced as sensations of warmth, sting, taste, touch, pain or whatever (Husserl 1952: 155; Husserl 1989: 163). The physio-psychical conditionality thus only works when the body is already subjectively lived as Leib. Physio-psychical causality can only work if the link between the psyche and the body is already established. This means that although physiological changes of stimuli also cause changes in the sensations, they don’t establish that causal relation. The Leib’s sensitiveness is not a non-physical consequence of physical processes for Husserl. Where the state of sensation of the body is indeed causally dependent on physiological processes, which again are causally dependent on physical contact with other physical entities, sensitiveness itself is not an effect of these processes since the causal mechanism only works when consciousness, and more precisely subjective experience is already in play. In a sense, one could say that Husserl addresses here in his own idiom what was later termed the problem of the explanatory gap, namely how physiological processes give rise to conscious experiences. Husserl doesn’t venture an explanation, which he actally seems to reject, he merely records a plain fact when he writes:

 (…) If my hand is touched or struck, then I sense it. We do not here have the hand as physical body and, connected with it, an extra-physical consequence. From the very outset it is (…) a hand with its field of sensation. (…) i.e. a physical-aesthesiological unity. (Husserl 1952: 155; Husserl 1989: 163)

16The Leib is a very specific entity then, a subjective objectivity (subjektive Gegenständlichkeit), with both material and subjective, non-material properties, between which there is a special causal link that explains the changes in the last properties by the changes in the first (Husserl 1952: 153; Husserl 1989: 160). The link is special because it does not imply that one of the two relata is constitutive for the other, since it only regulates their interdependence. There is no causal constitutive link between the two properties (physiology and sensitiveness) of the same object (Leib-Körper), but only a relation of causal covariation. It is not the stimuli that cause the sensations, since sensed stimuli are sensations. That is why Husserl speaks of a physical-aesthesiological unity. Consequently, when the stimuli change, this also causes a change in the sensations. We can only separate these two aspects (physical and aesthesiological) in the abstract, and only in the abstract, Husserl emphasizes (Husserl 1952: 155–6; Husserl 1989: 163). We need here a complex approach that is at the same time naturalistic, i.e. psychophysical and subjective, without reducing these analyses to one unique paradigm as the naturalist does. Accepting the necessity of an original unity of bodily and conscious processes, a unity which cannot be explained causally although the processes themselves are causally linked, doesn’t lead to a dualistic interpretation of sensitivity. The Leib is a causal reality and can also be considered as a material object, but it differs from other material things since it has specific relations of dependency which concern its sensitiveness. So it makes sense for Husserl to say that the “sensations are not properties of the Leib as a physical thing” — sensations are not material but subjective properties —,”but on the other hand, they are properties of the thing Leib” — which is more than just a physical object, — since they are causal “effect properties” — they are affected by physiological changes, which result from the causal interaction of the body with other objects (Husserl 1952: 146; Husserl 1989: 153–4). The external cause of physiological stimuli also causes the sensations, but doesn’t explain why the stimuli are sensed.

17Although stimulus and sensation are both properties of the Leib-Körper and are causally linked, Husserl refuses to identify them because the sensation is not a physical or material, but a subjective property. That is why he calls the Leib a subjective object. Consequently, reducing the Leib to a Körper (physical body) with purely material or physical properties as naturalism does, is an example of a category mistake, which creates (material) absurdity when one tries to understand the sensitiveness of the body. The absurdity arises when one tries, as naturalism does, to causally explain a non-material, subjective property by a material, objective one. And this already rests on a miscomprehension of the body, which constitutes another aspect of the material absurdity characteristic of naturalism. The body simply is not originally experienced as a physical reality on which a psychical, mental, conscious layer is functionally dependent. On the contrary, my body is subjectively lived (erlebt) or experienced. The body is corps vécu, as Merleau-Ponty says. The sensitiveness of the body means that there is a pre-reflective self-givenness of bodily sensations, which we may term bodily self-awareness. These experienced sensations display all of the properties that define consciousness: subjectivity or first-person givenness, immediacy, etc. The interpretation of the body as a physical reality (Körper) and the ensuing quest for a naturalistic explanation of consciousness presupposes this experience of the lived body (Leib, corps vécu), and results from an approach which makes abstraction of this self-awareness.

18Not only is the naturalist incapable of correctly describing this phenomenon, she equally comes up with strange explanations of the properties of the lived body. When you start describing the body as a Körper, you then have to explain how those non-physical, psychical properties are linked to it. The naturalist conjures up the question of how non-conscious biological processes can give rise to the subjective experience of embodiment. This question can only arise because of an implicit dualism, which accepts a distinction between non-conscious physical processes and conscious experiences. This problem is of course unsolvable, as we know since we have been instructed about the explanatory gap. Following Husserl, this question is simply absurd. It is wrong because the analysis of the sensitiveness of the body is wrong. The body is not a non-conscious organism on which conscious processes supervene and whose cause has to be identified. As remarked earlier, the Leib’s sensitiveness is not a non-physical consequence of physical processes for Husserl. Conscious embodiment will always stay a crux interpretum for any naturalistic analysis because it rests on a category mistake. The Mind-Body problem — how to reduce the mind to the body — is the result of the category mistake which consists in understanding the body as a physical organism. A correct phenomenological description and ontological understanding elucidates that this reduction of Leib to Körper is unjustified and that there is no Mind-Body problem such as naturalism conceives of it. Because the body is subjectively lived, because of the presence of this pre-reflective bodily self-awareness, it makes sense to say that the body itself experiences. As a sensing organism, the lived body is clearly more than just a physical cause of conscious experience, it is rather a constitutive element of it. Therefore the embodiment of a conscious person cannot be fully captured by a functional, psychophysical approach, which distinguishes between non-conscious bodily processes and conscious mental processes like sensations and then asks for their relation. Contrary to what naturalism claims, the body is not a physical cause of conscious perception. One should even say that certain bodily processes do not cause consciousness, but are themselves invested with it. This is clearly the case for the body’s sensitiveness.11 Of course, there is more to the body than its being the seat of consciousness. It is also the mode of existence of a person. And here naturalism utterly fails. Husserl calls the lived body a voluntarily movable organ of perception (frei bewegliches Wahrnehmungsorgan) (Husserl 1952, 56; Husserl 1989, 61). Embodiment is lived as a “je peux”, i.e., as a capacity to act (Merleau-Ponty, 1945: 160). Movement generates kinaesthetic sensations, which are sensed together with tactile and other sensations.12 Perception is only possible for a person that disposes of her body as a voluntarily movable and sensitive organ of perception (Walten) (Husserl 1973: 128; Husserl 1976-2: 220–1). Lived embodiment is the essential mode of being of perceptual consciousness. But it is also more, since the role of embodiment is not confined to perception. It is the expression of personal life, which consists of the character, intentions, actions, decisions, etc., of a person.

19By generalizing this point, it could be argued that the absurdity of naturalism entails that the physicalist cannot succeed in explaining other essential features of human existence such as subjectivity and intersubjectivity, intentionality and ethics, to name only the more important topics and core problems for any naturalistic approach. These features are either reduced or eliminated, and the naturalist claims that this is necessary in order to avoid what she calls unsolvable riddles and pseudo-problems created by a non-naturalistic approach: the explanatory gap problem, the problem of the other mind, the problem of content and causality of intentional acts and the problem of the status of ethical and other values and norms. But it should be remarked that a correct phenomenological analysis shows these phenomena to be very well explicable, and the so-called Scheinprobleme identified by naturalism to be problems conjured up by naturalism itself, and which can be very well treated by a non-naturalistic phenomenology. I referred to the absence of a Mind-Body problem for the phenomenological approach of lived embodiment, but one could also develop the theory of empathy to show how the so-called problem of intersubjectivity is not at all a conundrum for phenomenology as naturalism pretends it should be.

20Moreover, naturalism is actually an abstract approach of man in the context of the natural attitude. Naturalism with regard to man is an explanatory strategy, which is based on a more original experience. As Husserl remarks, we never encounter other humans as particular physical bodies on which a psychical layer is causally dependent. We naturally encounter other persons, and this means something completely different. Our most natural attitude is actually personalistic. If we try to reduce human behaviour to its physical causes, we not only import scientific categories into the human realm, but we also eliminate what is typical for man. Husserl speaks of a „surplus“ which is not contained in the type of approach the naturalist adopts (Husserl 1952: 140; Husserl 1989: 147). To explain depression by a malfunction in the brain due to a reduction of serotonin and melatonin is a valid scientific insight, but it is an oversimplified abstraction and in that sense it doesn’t really help us to understand the behaviour of the depressed person and the other multiple personal, psychological, existential, social, relational etc. reasons of her pathology. Physiopsychical dependencies do not suffice to understand the subject and her properties, what Husserl also calls the personal or spiritual (geistige) individuality of man (Husserl 1952: 139; Husserl 1989: 147). We also have to take into account how man’s personality is motivated by his social and cultural environment. In order to understand how man relates to his environment, categories such as causality and explanation can play no role. Motivation and understanding (Motivation and Verstehen) belong to another region. Physicalism, which reduces all phenomena to physical processes, thus leads to a loss of man. “Vom ganzen Menschen ist nichts mehr übrig”, says Husserl quite firmly(Husserl 1992: 158). Man is more than a psychophysical being, and consequently understanding and explaining his existence requires another approach. Although physicalism can contribute to the study of man in so far as he is an animated being, it is nevertheless diagnosed as absurd (widersinnig) when it pretends to be the correct understanding and explanation of man. The naturalist doesn’t talk nonsense (Unsinn) then, nor is what she is saying contradictory — she doesn’t necessarily commit any logical mistakes as in the case of formal or analytical absurdity — but her approach of man is materially absurd by confusing regions. It is only in so far as man can be considered as a part of physical and biological nature that naturalism concerning man’s organism is valid. But any claim to a complete understanding and explanation of human behaviour and culture is absurd.

21So with Husserl I conclude that naturalism about human existence in general and about the body in particular results in a meaningful, non-contradictory but nevertheless absurd theory, which has to be exposed as the result of a category mistake. If it comes to understanding the body’s sensitiveness, it is clear that a causal explanation can only explain the functional dependency of sensations on stimuli, but can never elucidate the subjective experience of these sensations. In contemporary terms, one could hear Husserl say that the explanatory gap is unbridgeable. But his claim is actually stronger. There is no explanatory gap, this gap closes itself when one leaves a purely naturalistic approach and starts from the experience of the body as a freely moveable organ of perception and as the expression of personal life. This “subjective object” is subjectively experienced as the sensitive organ of perception, invested with consciousness. As remarked earlier, it is the mode of existence of perceptual consciousness and of personal life, which from the outset is embodied. Any attempt to translate this into a naturalistic problematic, which searches to causally explain the presence of sensations and other mental processes by non-conscious physiological processes, commits a category mistake, because one then applies to the body the notion of a physical organism, to which it is not reducible in so far as it is always sentient. Or to phrase it differently, sensitiveness is a property of the lived body, but not in so far as it is a physical thing.13

3. Possibility of a priori knowledge

22The main problem of this approach is of course how to found the claim that two entities, concepts or terms belong to different ontological regions or material categories, so that we know when a category mistake is being made. Ryle considered absurdities to be the key to detecting category differences. There is a category mistake if substituting one expression for the other results in absurdity. “Thus, e.g., the statement “She came home in a flood of tears and a sedan-chair” (Ryle 1949, 22) is (…) absurd, because it conjoins terms of different categories.” (Thomasson 2013) But for Husserl, this strategy is not available. Since material absurd expressions are syntactically well formed and also meaningful, since they are neither non-sensical nor contradictory, the absurdity of the expression cannot be detected as easily as in Ryle’s example.14 As indicated above, one needs ontological knowledge of the regions in order to identify the category mistake. Material absurdity is for Husserl a logical notion, based on ontology, and is not necessarily rendered in linguistic absurdity.

23The ontological knowledge of the proper nature of a region is a priori, eidetical knowledge. But it is not analytical. So Husserl would not agree with the rejection by the Vienna Circle of the possibility of a priori knowledge which is not purely analytical. Eidetical knowledge of an ontological region is arrived at by a process of abstraction that takes its origin in phenomenological description, i.e. in a form of empirical description. Of course, the exact nature of this description is a major subject for phenomenology, since the criticism of naturalism rests on the claim that a description in the so-called naturalistic attitude (naturalistische Einstellung) misreads the data. As Husserl said, “back to the things themselves” also means to describe them as they present themselves, without a bias induced by empiricism, scientism, naturalism or positivism. He firmly argued for the need for a more original approach of human existence in his Ideas II, where he showed that an unbiased description of what he termed “the world of natural experience” (natürliche Erfahrung) calls for the so-called personalistic attitude (personalistische Einstellung) which only guarantees a correct experience and description of the region of the Geist or human existence. Only the phenomenological description and analysis in this attitude can found the ontology of the Geist, which is the tool to identify naturalism as committing a category mistake when it interprets and understands human existence as an element of physical nature. The phenomenological description and analysis of the lived body and the critique of its naturalistic interpretation as a Körper given above illustrates what this means.

24Others have explained the method Husserl uses to obtain this a priori knowledge and which he calls ideative abstraction (ideierende Abstraktion).15 So I can summarize here this threefold method. We start from the unbiased, original experience of an object, and then try to identify its constitutive elements. We do that by varying freely, eventually with the help of fantasy, its form, properties etc., in order to determine the basic, structural elements which constitute the object. These features appear to us as invariant on the basis of overlapping syntheses (Deckungssynthesen) between the different fantasized variants of the object. Thirdly, these essential properties become the object of a proper act of thought, the so-called Wesensschau. Let us consider shortly each of these three aspects.

25Original experience means that one tries to describe how the object is given, what kind of experience is necessary in order to experience this particular object. As I remarked before, Husserl insists for instance that we cannot experience our proper body as a physical object, because of its sensitiveness. If I cut my finger, I immediately have a pain-experience. This is where to start from, namely how the body is given. Sensitiveness is a basic property of this “object”, and one can describe what this means for the experience of the body: it is not a material object, but a so-called subjective object because it is subjectively lived. It is thus given in a specific experience, the experience of lived embodiment.

26We identify the constitutive elements of the object with the help of fantasy, which enables us to freely alter the object. Through this process of free variation, it appears that even this fantasy has to comply with certain rules. If we try to determine for instance what is essential for a material object, we can arbitrarily alter its form, movement, properties and even venture to neglect common physical rules. But it is unalterable and necessary that the object will have to appear in a spatio-temporal continuum, and that this has implications for the way its properties appear. It follows for instance that every colour is spatially extended, that every tone has a duration. In this way we discover a priori rules for the perception of a material object, more precisely that it has to appear as a spatio-temporal thing. These rules also determine the essential, structural properties of the object itself, which are objects of the so-called overlapping syntheses. This synthesis picks out the element that is necessarily the same in all the different representations of the object, which is freely changed in fantasy.

27Finally, this leads to the identification of a common core element, which is grasped as the eidos. This grasping is a form of thinking, more precisely categorical thought (kategorisches Denken). The “idea of the object” designates a categorical or regional a priori norm which necessarily determines every further specification of an object that belongs to this category. The eidos is for Husserl the object of a proper “Denkakt”. Ideative abstraction results in the givenness of the eidos as the essence or the invariant core of the object. This essence is the object of a proper intuition, the so-called Wesensschau. So, although it is arrived at through a process of careful description of the experience of the object, which is then subjected to variation in order to identify its common constitutive elements with the help of overlapping syntheses, the essence itself is not an abstract concept which is the result of a process of generalization. The latter procedure leads to empirical generalization but not to the intuition of the essence. Husserl thus claims that the eidos is the object of a proper apperception, although it is arrived at through the procedure of ideative abstraction. The eidetical method and its specific intuition are of a proper kind. Since Husserl developed this method in his struggle against psychologism, he clearly emphasizes its difference from empirical generalization. When one starts with a particular object and concentrates on one of its characteristics, and then subjects it to imaginative variation, this aspect of the object, which appears as constant throughout the different variations, becomes the object of a new intuition, whereby it is grasped as an idea. One should avoid interpreting this in a Platonic or metaphysical sense, although the terminology is clearly Platonic (Fonfara 2008). Yet it is clear that the eidetical structures are the essential structures of reality and do not exist in themselves. Husserl developed in Ideas III the example of the eidos of a material thing.16The analysis of the human, spiritual world and its essential structures can be found in Ideas II, which is a masterpiece of Husserlian constitutive analyses, where the experience and the correlative material ontology of nature, animated nature and “spirit” are described. This leads to eidetical insight in what is typical of these three regions, and in what sense they need to be distinguished. Blurring these categorical distinctions by interpreting one of the regions with notions that essentially belong to another amounts to material absurdity. Naturalism with regard to human existence commits this absurdity, for instance when it naturalizes the mind.


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1  I say inadvertently, because Ryle is not “denying that there are mental processes” and because he doesn’t argue for a reduction of Mind to Matter. Such a reduction is impossible since it presupposes the legitimacy of their distinction. (Ryle 1990: 23–4)

2  See, for example, Carnap’s famous article entitled “Überwindung der Metaphysik durch logische Analyse der Sprache” (Carnap 1959). It should be remarked that this longstanding translation is not really correct. Carnap doesn’t want to eliminate metaphysics. The title of his article is about overcoming (Überwinding) metaphysics, which means that it has to drop its cognitive pretence. But as the expression of an attitude to life it is still quite legitimate like literature, poetry and above all music.

3  Carnap argued that although metaphysics can be understood since it uses meaningful words, it is cognitively nonsensical because it is neither analytically a priori nor synthetically a posteriori, empirically significant, knowledge. Metaphysics is nonsensical because metaphysical statements cannot be proved or disproved by experience. “(…) Metaphysics (…) is compelled (…) to combine meaningful words in such a way that neither an analytic (or contradictory) statement nor an empirical statement is produced.” (Carnap 1959: 76)

4  In § 7 of (Husserl 1971), Husserl develops the ontology of the thing as res extensa, which he calls exemplary (Husserl 1971: 25–37).

5  About this ontology of the lifeworld and the problem of the different regions, see (Husserl 1992, Text 11: 140–60). This text is also relevant for the critique of physicalism.

6  For the definition of regions, see (Husserl 1974, § 55); also (Husserl 1985, §§ 92–3: 432 ff.), (Husserl 1971, §§ 7 and 19), (Husserl 1995, § 62 and Beilage XVII).

7  (Husserl 1952: 91), (Husserl 1971, § 3: 13, also §§ 5, 6, and 7). Husserl writes that “the idea of each science”, and more precisely “the idea of its method (is) founded on the proper essence of the idea of its object” (Husserl 1971: 13).

8  “(…) das Wesen der Gegenstände und das zugehörige Wesen möglicher Erfahrung von Gegenständen der betreffenden Kategorie (…) schreibt alles Prinzipielle der Methode vor.” (Husserl 1971: 22)

9  See the title of § 34 of Husserl 1952: Necessity of the distinction between the naturalistic and the personalistic attitudes.

10  Husserl mentions the Santonin eating experience, which makes us see things as yellow. This refers to Mach and Helmholtz, whom Husserl doesn’t mention. (Husserl 1952: 62 ff.; Husserl 1989: 67 ff.)

11  Already in Ding und Raum and more extensively in the second book of his Ideas and furthermore throughout several other volumes, Husserl makes this point about the specificity of embodiment which cannot be understood in a naturalistic stance.

12  Kinaesthetic sensations are a special kind of sensations, because they motivate what Husserl called “Merkmal-Empfindungen”, i.e., sensations of sensory qualities of objects.

13  For Husserl, the existence of non-material properties of physical objects is not limited to the body and does not constitute any mystery. The beauty of a landscape, the meaning of words, the cultural significance of a church are further examples of what he calls non-material, ideal properties of material objects. These objects have to exist materially in order for these properties to be present, but they can not be identified with or reduced to any of their material properties. There is nothing mysterious about this.

14  As has been remarked, this test is not very convincing, since it allows for absurdity even when terms belonging to the same category are substituted for one another. “Thus ‘the seat of the — is hard’ works if ‘chair’ or ‘bench’ is put into the blank, but not if ‘table’ or ‘bed’ is. And if furniture words do not form a category, we may well ask what do.” (Smart 1953: 227)

15  See (Lohmar 2003: xviixli), and the bibliography in the various notes of this introduction. About the threefold method, see p. xxii.

16  See § 7: Regionale Begriffe und “Gattungs”-Begriffe, in (Husserl 1971: 25–37).

To cite this article

Peter Reynaert, «Does Naturalism Commit a Category Mistake?», Bulletin d'Analyse Phénoménologique [En ligne], Volume 11 (2015), Numéro 3, URL :

About: Peter Reynaert

Universiteit Antwerpen

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