Brentano on Perception

Guillaume Fréchette Brentano on Perception I. THE STANDARD VIEW Thanks to his account of mental acts, Brentano is usually acknowledged as the philosopher of intentionality. What characterizes mental acts is their intentionality, that is, their directedness towards an object (Brentano 1874–1973. 68–124). Another important contribution of Brentano to contemporary philosophy lies in his conception of consciousness. In his view, mental acts are not only characterized by their intentionality with regard to their objects, but are also concomitantly self-directed (ibid. 180/98). This self-directedness is what makes them conscious. Since intentionality and consciousness are two central marks of the mental, they also apply to perceptual acts as well. An act of sensory perception, insofar as it is mental, is intentional and conscious. It is worth noting, however, that while many philosophers have acknowledged in recent years the intentionality mark for the mental, the consciousness mark is rarely challenged.1 This perhaps explains in part why Brentano’s account of perception has received so little attention in the secondary literature. If, following his view, perception has to be intentional and conscious, then it seems that the conditions for any mental state to be a perception are very strict, perhaps too strict: we may want to say that there is always an (intentional) object in every perceptual act, but we may want to dispute that every perceptual act is therefore also conscious. Or conversely, we may want to say that every perceptual act is conscious, but we may want to dispute that every perceptual act therefore has an (intentional) object. Another possible explanation for the recent lack of interest in Brentano’s philosophy of perception may be found in one common interpretation of his conception of intentionality, according to which the objects of intentional acts are 1 See Textor 2017 on disputing the intentionality mark. 14 UNITY AND TENSIONS IN AUSTRIAN PHILOSOPHY immanent objects, that is objects that have “some kind of reality in the mind”.2 Following this interpretation, if intentionality is the mark of the mental, then perception is nothing but a special case of intentionality, understood as a relation between a mental act and an immanent object. In other words, following the common interpretation of Brentano’s conception of intentionality, what one perceives is merely an intentional object that is an object in the mind; it is not an ordinary spatiotemporal object. On this interpretation, it seems as if Brentano would defend a view of perception along the lines of the argument from illusion.3 Following this common interpretation, it seems at first glance that Brentano’s account of perception would fall somewhere between phenomenalism and idealism, not only concerning perception, but thought as well. It remains disputable, however, whether what Brentano calls the intentional relation really is nothing more than a relation to a sense-datum (or, in the case of thought, to an idea), and whether perception, in his account, has to be understood as a special case of intentionality. Concerning the first point, we should bear in mind that in his later writings, he insisted on calling intentionality something “relation-like” (etwas Relativliches), abandoning the idea that it is a relation in the proper sense. Concerning the second point, even in the Psychology from an Empirical Standpoint, he stresses many times the point that there are external objects causing our so-called “physical phenomena” (the seen blue, the heard sound, the seen landscape, etc.). Since standard phenomenalist or idealist theories would not require this further premise, they would not likely bring it in. If there is an external world producing or causing our physical phenomena, as Brentano suggests, how is this suggestion understandable if the external world is given to us exclusively in a perceptual relation, understood as an intentional relation between a mind and its immanent object? One way of understanding this suggestion in the framework of a conception of perception as a particular case of intentionality – understood as a relation be2 At least following one common reading of “intentional inexistence” propounded most notably by Chisholm 1967 and Smith 1994. 3 Hume 1748 had a first version of the argument. Based on Smith 2002, Crane and French 2016 propose the following reconstruction: (i) In an illusory experience, it seems to one that something has a quality F, which the ordinary object supposedly being perceived does not actually have. (ii) When it seems to one that something has a quality F, then there is something of which one is aware which does have this quality. (iii) Since the ordinary object in question is, by hypothesis, not-F, then it follows that in cases of illusory experience, one is not aware of the object after all. (iv) The same account of experience must apply to both veridical and illusory experiences. (v) Therefore, in cases of veridical experience, one is not aware of the object after all. (vi) If one is perceptually aware of an ordinary object at all, it is in either a veridical or illusory experience. (vii) Therefore, one is never perceptually aware of ordinary objects. GUILLAUME FRéCHETTE: BRENTANO ON PERCEPTION 15 tween a mind and its immanent object – is to consider it highly improbable that our sensory contents are not produced by anything in the physical world. Rather, it is highly probable that our sensory contents are produced by something physical (atoms, particles, energy fields, or forces). But probability, even very high or infinite probability, is not evidence. Since evident perception, that is, inner perception, is apparently for him the concept of perception par excellence, then there is no proper perception of the external world. Brentano often make this point or similar points.4 Understanding perception exclusively in the strong sense of evident perception, and as a particular case of intentionality (understood as a relation to an immanent object) seems to lead to a reading of Brentano in which the objects perceived are mere perceived contents or possibilities of sensations, a reading close to Mill’s (or even Berkeley’s) phenomenalism.5 This too may help explain why Brentano’s account of perception, given the common interpretation of his conception of intentionality, has received so little attention: if Brentano’s account of perception is understood as it has usually been interpreted, then it is not meaningfully different from the account already offered by phenomenalist and idealist theories. In this case, it would be entirely understandable why Brentano’s account has been neglected. But even if we accept this reading of Brentano’s account of perception, there is an important difference between Brentano’s account of perception and Berkeley’s, Mill’s, or Mach’s. As we have already emphasized, while Berkeley considers physical objects in terms of sense data, the existence of which depends upon their being perceived, and invokes God’s perception for filling the gaps for cases where we are do not actually perceive anything, Brentano does acknowledge that the world exists independently of our perception of it. He simply raises serious doubts about the idea that we perceive it exactly as it is. He thus avoids a position such as Mill’s, where the permanent possibility of sensations accounts for the fact that physical objects are not always perceived. He also avoids Mach’s phenomenalism by stressing the ontological distinction between the mental and the physical, which Mach rejects. Thus, the common interpretation of Brentano’s account of perception as a form of phenomenalism is not particularly plausible, even on the standard reading. His position, according to the standard reading, therefore contrasts with 4 See for instance Brentano 1874/1973. 11/9; 128 ff. Jacquette 1996. 138 and 1990. 179 ff. suggests that it was the immanent intentionality thesis that led Meinong, Höfler, and Twardowski to introduce the content–object distinction and, by it, to abandon the “self-enclosed idealism implied by Berkeley’s empiricism” (1996. 138), which was characteristic, in Jacquette’s view, of Brentano’s conception of intentionality. I explain why this historical reconstruction provided by Jacquette is problematic and why Brentano did not defend the immanent intentionality thesis in the way suggested by Jacquette and many others in Fréchette 2017. 5 16 UNITY AND TENSIONS IN AUSTRIAN PHILOSOPHY idealism and phenomenalism. It seems to suggest that he would defend a view similar to critical realism. But again, this is not the case: against Locke, Brentano doesn’t distinguish between primary and secondary qualities concerning their relation to the observer: for him, extension and colour are given on the same basis in perception. If Brentano sides neither with Locke nor Berkeley, neither with Mach nor Mill, how should we understand his position? Here, defenders of the standard reading have divergent opinions, but since perception seems to be the enfant pauvre of Brentano’s theory of intentionality in the standard reading, scholarly discussion has been relatively sparse.6 However, the standard reading of Brentano – according to which he believes that intentionality is a relation to an immanent object, and perception is a special case of intentionality – has a grain of truth, at least insofar as there are many passages from the Psychology from an Empirical Standpoint that seem to support this reading. But as mentioned above, there are obvious problems with this reading when it comes to Brentano’s supposition of an external world directly responsible for what we see, hear, etc. Furthermore, Brentano’s criticism of phenomenalism7 makes it difficult to champion a reading on which he appears to defend a variety of this same phenomenalism. In short, the common reading of Brentano’s thesis on intentionality attributes to him a suboptimal account of perception which does not fit with his critique of phenomenalism. Furthermore, it suggests that Brentano should be seen as a defender of the argument from illusion. But if causality is a relation that, according to him, operates between the external world and physical phenomena, and if the external world is not a simple theoretical posit but something of which perceiving agents are parts, then there must be a way in which, as perceiving agents, we are after all related with the external world. II. TENETS OF THE STANDARD VIEW In order to address this issue, let us summarize in a few general theses the gist of Brentano’s conception of perception according to the standard interpretation. T1: Perception is a special case of intentionality T1 is simply a repetition of the common interpretation of Brentano’s theory of intentionality, according to which intentionality is a relation to an immanent ob6 Brentano’s account of perception has been directly or indirectly discussed recently in Mulligan 2004, Textor 2007, Fisette 2011, Seron 2017, 2017a and Massin 2017. 7 See for example Brentano against Mach (Brentano 1988), but also Brentano’s lectures on positivism from 1894–95 (Brentano 1894–95), where he defends the view of a correlation between the seeing and the seen (against the identification proposed by Mach), advocating at the same time for the irreducibility of causality. GUILLAUME FRéCHETTE: BRENTANO ON PERCEPTION 17 ject. Since all mental phenomena are intentional in Brentano’s view, and since perceptual experiences (hearing a sound, seeing a colour, etc.) are mental phenomena, it follows that all perceptual experiences are intentional. T2: Perception is of something that truly exists T2 is a foundationalist thesis insofar as it restricts the use of “perception” to the perception of things that truly exist. If only mental phenomena truly exist (this thesis is expressed in the basic idea that physical phenomena exist only intentionally (or better: inexist) in the mind, while mental phenomena truly exist), and if perception (Wahr-nehmung) is, by definition, perception of something that truly exists, then only inner perception (that is perception of mental phenomena) is perception in the relevant sense of the term. T2 imposes obvious epistemological restrictions on the application of the term “perception”: if there is a strong sense of perception in which what we perceive is what truly exists, then only inner perception is perception in the true sense (Brentano 1874/1973. 119–170). Following the standard account, this thesis may explain Brentano’s rejection of Berkeleyan idealism, Machian phenomenalism, and Lockean realism, since it acknowledges that there is a domain of what it innerly perceived, which is perceived as it is. T3: What we truly perceive is a mental-phenomenon-containing-something T3 addresses in part the issue that was left undetermined in T2, namely the actual contents of so-called sensory perception. Brentano comes to T3 from the following premises: (a) only mental phenomena truly exist (i.e. only mental phenomena are objects of inner perception); and (b) objects of mental phenomena are inexisting objects (colours, chairs, landscapes, etc. as “intentionally contained” in the mental phenomenon). Therefore, what we “truly” (or innerly) perceive is what one could call a mental-phenomenon-containing-something. The hyphens here are meant to stress, first, the fact that what is innerly or “truly” perceived is not simply the seeing, the hearing, etc., but the hearing as the hearing of some specific tone, the seeing as the seeing of a specific colour, etc.; and second, that sensory contents are perceived only to the extent that they are intentionally contained in a mental phenomenon, which is the actual object of perception. Sensory contents are only indirectly perceived, so to speak, that is, as part of a mental phenomenon. III. THE NAÏVE UNDERSTANDING OF PERCEPTION On the face of it, these three theses leave no room for anything but a restricted concept of perception, namely, that of inner perception. It is easy, on the basis of T1–T3, to understand why most readers of Brentano take him literally when 18 UNITY AND TENSIONS IN AUSTRIAN PHILOSOPHY he writes at numerous places that only inner perception is perception (Wahrnehmung) in the proper sense.8 Characterizing inner perception as the only kind of perception (and characterizing outer perception as the mere reception of physical phenomena) seems to lead Brentano to reject the naïve understanding of perception (or perceptual experience) in terms of “openness to the world” (McDowell 1994: 112), according to which we are presented, in perceptual experiences, with ordinary mind-independent objects, and that in such experiences we are aware of such objects.9 This would support an understanding of Brentano’s position as defending the argument from illusion. Following the account at the basis of the three theses, it seems that no mind-independent objects are directly involved in perceptual acts. Moreover, T3 in particular makes it clear that Brentano would reject the transparency intuition that is often shared by philosophers who believe that our experience gives us features of mind-independent objects. In short, it seems that Brentano’s account of perception, following the standard view, cannot account for the basic intuition that perception is primarily of something other than itself. Is this a plausible reading? I doubt it. Taken literally, it would mean that what I truly perceive when I am seeing a barn is not the barn but the seeing. While this view may capture in some way the intuition that we are aware of something in perceptual experiences, it leaves out too much from our naïve understanding of perception in order to count as a plausible account of perception. After all, when I see the barn and when I see a church, there are some obvious differences in my perceptions. Cashing out these differences simply in terms of modulations in the seeing implausibly downplays the naïve intuition that these perceptions give me some information (erroneous or not) about the world, not merely indirectly as what is contained in a mental act, but perhaps even directly about the location and various features of certain objects. If Brentano does reject the positions of Berkeley, Locke, Mill, and Mach on perception, then he should have more to say about this naïve intuition than simply dismissing it. He ought to acknowledge some kind of perceptual process through which my sensory organs gather information (both correct and incorrect) about my environment. The existence of such process could hardly be denied if the hypothesis of an external world is to be justified at all. Although T1–T3 plausibly explain the lack of interest in Brentano’s account of perception, they are neither a plausible rendering of Brentano’s view of perception, nor are they compatible with some important insights by Brentano on 8 Ibid. This was already the case with Husserl in the Logical Investigations (Husserl 1901/2001), who set the tone for the interpretation of Brentano in the phenomenological tradition, in Heidegger 1992[1925]. 46. for instance, and later on in Føllesdal 1969. 680–681 and Jacquette 2006. 107, among others. See Hickerson 2007. 42 ff. for a discussion of the problems raised by this reading. 9 On awareness, see Crane and French 2016. GUILLAUME FRéCHETTE: BRENTANO ON PERCEPTION 19 the nature of perception that are rarely discussed in the secondary literature. Although it is true that for Brentano, inner perception has a priority over outer perception in the order of investigation, this priority does not imply that there is no outer perception properly speaking, or that “perceiving your sensing” is the only case of perceiving. In the rest of this paper, I will argue that T1–T3 are meant to provide an account only of inner perception: that they are meant to provide instances of “good” perception, not of perception in general. IV. TWO OPTIONS FOR THE STANDARD VIEW For a defender of the standard view, there are two main options in interpreting Brentano’s theory of perception, both of which would account for the idea that truly perceiving the barn is actually perceiving the seeing (which contains, in some special way, the barn as its intentional object). The first option is a relational account, which can be spelled out in two different ways. (1) First, one could argue that we directly perceive mental images (or physical phenomena, in the Brentanian sense) which are dependent on the mind, and that these have the properties that perceptually appear to us. Such a view basically amounts to a sense-data theory. We have already seen that Brentano would not endorse such a view in the framework of phenomenalism.10 The problem with such an account is that it introduces a veil of perception which makes our relation to the world highly problematic. Here again, it would make Brentano a defender of the argument from illusion, which does not fit with his critique of similar positions. (2) Second, one could also try to argue for the relational account in terms of some variety of representationalism or intentionalism, conceiving of perception as a special kind of relation between one’s mind and the intentional object, mediated by the representational content. Crane (2009, 2009a, 2013) defends a similar view, though he maintains that his view is not relational as such: I can represent a golden mountain although there is no such thing; However, he seems neutral as to whether it actually fits with Brentano’s. Following this view, in perception a given object seems to me in a particular way: the “seeming to me in a particular way” can be explained in different ways. It might be explained in terms of representational content alone; for example, I see the barn as an old and unoccupied brownish building in the middle of the field. It may also be cashed out, at least partly, in terms of the mode or attitude of a specific experience: 10 Of course, there is another option that is at least technically open: one could also accept the sense-data theory without accepting phenomenalism, as in causal theories of perception for instance (e.g., Price 1932). But such theories are usually designed as a justification of our belief in the external world. Brentano’s account, however, both in the standard view and in the view argued for here, takes our belief in the external world to be primitive and unjustifiable. 20 UNITY AND TENSIONS IN AUSTRIAN PHILOSOPHY seeing the barn is in this respect a different experience from merely imagining or remembering it. Independently of the question whether or not the mode or attitude plays a role in determining the phenomenal character of an experience, a representationalist account of Brentano’s position should lead one to consider perception as (at least partly) determined by the representational content, that is, by the physical phenomenon. There might be an object which is represented – there might actually be such a barn in the field – but the experience represents a barn not in virtue of the existence of such a barn, but rather in virtue of being more or less accurate: for instance, an experience such as seeing the barn as floating above the field is likely to be less accurate than an experience such as seeing the barn as standing on the field. Whether Brentano would agree that representations (or rather, presentations, Vorstellungen) represent in virtue of being more or less accurate can remain an open question for now, but if intentionalism is an option for the standard view, then it seems that only judgements of inner perception (of the form “Seeing exists”, for instance), and not presentations per se, have correctness conditions and can be assessed for accuracy. Intentionalism therefore seems (at least on the face of it) not to be a real option for the standard view. Even if we put this concern aside, it is also questionable whether Brentano would agree that representations represent in virtue of being the bearer of some semantic information, which is an essential component of a representationalist or intentionalist account. In the best case, intentionalism would fit only loosely with the standard view: Brentanian physical phenomena, in the standard view, are not really bearers of semantic information: they are not representational, and they are not, properly speaking, about the world in the sense that my seeing is about the “green as perceived.” Certainly, Brentano sometimes calls them “signs of something real” (Brentano 1874/1973. 24/14) in a way which evokes Helmholtz’s theory of perception, but unlike Helmholtz he rejects the idea that these signs carry information about the actual localization of the external stimulus, information which according to Helmholtz is processed by unconscious inferences.11 In short, Brentano’s physical phenomena are signs of an outside reality, simply on the (highly probable) assumption of the existence of an external reality; however, if one sticks with the standard view, they do not seem as such assessable for accuracy, nor do they represent something else. Finally, and most obviously, intentionalism cannot account for the non-distinction view between content and object which is presupposed by the standard view.12 In the intentionalist account, intentional objects are not identical with the contents of mental acts, as presupposed by the standard view. 11 See Brentano 1979. 69 for a critique of Helmholtz’s position. More on this below. I discuss the non-distinction view and proposes an alternative based on Brentano’s view in his lectures on descriptive psychology in Fréchette 2017. 12 GUILLAUME FRéCHETTE: BRENTANO ON PERCEPTION 21 For these reasons, a relational (in this case representationalist) reading of Brentano’s views on perception seems not to be very helpful for the standard view. Against such a reading, one can favour a non-relational reading of perception along the lines of adverbialism. According to this account, intentionality is quasi-relational, that is, the intentional content of one’s mental act should be understood as a property of the perceptual experience itself rather than as some kind of object with a particular kind of existence. According to adverbialism, I do not see coloured objects, since colours are strictly phenomenal properties (and such a view fits well with Brentano’s own view of colours). On this view, there is a common core between my seeing a yellow truck and my hallucinating a pink elephant, for in both cases phenomenal properties appear in the same way. The main problem with the application of this account to Brentano’s views on perception is that while it fits well with his reism, in which irrealia are banned from the ontology (and therefore we present things in this or that way), it cannot account for the idea that what is presented are intentional objects (and not merely modes of presenting), and that these are in some relation with the outer world (not as representations, but as signs). If we consider Brentano’s reism as his final word, not only in ontology, but in perception as well, then adverbialism may have some potential, but it entails the rejection of T3; adverbialism therefore seems not to be a real option for the standard view. Thus, it seems that the only way to make sense of the standard reading of Brentano’s view of perception is the relational account. It involves either ways however serious reconstruction under theoretical presuppositions that are not always plausible; this suggests that the alleged three tenets on perception (T1–T3) are perhaps giving a wrong picture of Brentano’s actual views on perception. V. THE BACKGROUND TO BRENTANO’S VIEWS ON PERCEPTION To give a plausible reconstruction of Brentano’s view, it might help to take a quick look at the background to his views on perception and his take on perceptual illusion. Let us start with the background. There are a few central ideas from the history of the philosophy of perception that played an important role for Brentano’s views. First, the Augustinian view distinguishing between higher and lower (sensory) perception already plays a role in the account developed in Die Psychologie des Aristoteles (Brentano 1867). In this context, sensory perception has a limited role: it is possible only through the active act of the soul, and not through bodily sensation alone (neque enim corpus sentit, sed anima per corpus). There are representations (similitudines) on the basis of the information (informatio) sent by the organs to the soul. Intentio, based on information, is our identifi- 22 UNITY AND TENSIONS IN AUSTRIAN PHILOSOPHY cation of the object perceived.13 Like Augustine, Brentano believes that sensory perception as such is possible only on the basis of an active act of the soul, or in Brentano’s conception, on the basis of inner perception. We find a similar idea in Descartes (c’est l’âme qui sent, et non le corps),14 with whom Brentano agrees (even against Aristotle!) at many places.15 In these cases, ideas (representations) are isomorphic figures, pictures, or (as Brentano calls them) signs produced by external stimulation. In all these cases – the distinction between lower and higher perception (Augustine) or the distinction between the stimulation on the retina and the produced images in the soul (Descartes) – one finds the idea that visual sensations, for instance, which are produced by the stimulation on the retina, are not by themselves responsible for our seeing; in order to really perceive the blue patch of colour in front of me, an active act of the mind is necessary. In Brentano, this act is called a presenting (Vorstellen). Against Reid, Brentano would refuse to say that the presenting and the presented are only “grammatically” distinct.16 A presenting really exists, while a presented is strictly phenomenal and merely “inexists” intentionally in the presenting. On this account, Brentano obviously advocates for the ontological priority of acts (like presentings) over their objects (the presented); in other words, it seems that he argues that the being of acts of presentation is a condition for the inexistence of physical phenomena. If “sensory perception” designates the reception of the nerve signal produced by the stimulation of the sense organ, which is experienced as “having a physical phenomenon”, then it seems that for something to count as sensory perception, there must be a conscious mental act which is intentionally directed at the physical phenomenon. This would also explain Brentano’s rejection of external perception (sensory perception taken in isolation from the acts in which we are conscious of it) as Falschnehmung. This reading of the relation between mental and physical phenomena in terms of the ontological priority of the former over the latter has the consequence that one would have to admit that there could still be sensory perception in a relevant sense even without any external stimulation of the sensory organs. This does not challenge the intentionality thesis, since Brentano accepts cases where we have physical phenomena that are not produced by external stimulation, as we will see below.17 But even if one accepts the ontological priority of the 13 On Augustine, see Caston 2001. 33 ff. Descartes, Dioptrique, Discours IV, A.T. VI, p. 109 (Descartes 1902. 109). 15 For instance Brentano 1975[1916]. 13 where he agrees with Descartes on this point against Aristotle, and praises Reid for doing the same. 16 Reid 1895 [1764]. 182 ff. Compare Brentano 1975. 4. 17 The other consequence of the ontological priority reading is that organisms with no mental phenomena (if there are such things) would be deprived of perception. Brentano however accepts this consequence. In his view, animals have no general concepts, and hence no higher intellectual activities: they only have sensations, affects, memory, and associative 14 GUILLAUME FRéCHETTE: BRENTANO ON PERCEPTION 23 mental over the physical, Brentano’s point seems rather to be that perception in the strong sense of T2 cannot be accounted for strictly in terms of physical phenomena produced by external stimulation of the sense organ, since we have no evidence that these phenomena accurately depict external reality. This line of thought about sensory perception may seem anti-realist to a significant extent, and when we put it in the context of its times, it obviously follows some important insights on sensory perception developed by Helmholtz under the influence of Johannes Müller, who can be labelled as anti-realist as regards the nature of perception. Müller (1837) thought that his law of specific nerve energies, according to which every sensory nerve reacts specifically and differently (as a light nerve, a sound nerve, a smell nerve, etc.) to a stimulation s, had the consequence that sensory perception is not perception of a quality of an external body, but of a quality of our nerves. This suggests that sensations cannot be seen as copies of external objects, but rather that they have a representational nature. This idea was also followed by Helmholtz, who argued that contents or sensations are rather signs that “completely depend on our organization” (Helmholtz 1878. 225 f.). Consequently, Helmholtz argued, perception should be seen as the result of this interpretation, this result being sometimes obtained through unconscious inferences. Brentano accepted Müller’s conclusion in his account of perception: it is not the quality of the external stimulation that determines sensation, but the specificity of the stimulated sensory organ. But does Brentano accept this simply on the basis of T2? In order to answer this question, it might be helpful to recall the views of Helmholtz and Hering, which both influenced Brentano to different extents. According to Helmholtz, Müller’s law also confirms that there is a distinction between sensation and perception. Sensations are produced by the stimulation of the nerves and are fully specified, following Müller’s law, by the specific characteristics or modalities of the sensory organs; nevertheless, we do interpret our sensations as giving us information about the position and form of objects in space (1867. 427). This interpretation is what Helmholtz calls “perception”. Perceptions, and only perceptions, are mental acts: sensations merely provide the material upon which perception operates. Hering, on the other hand, rejects the distinction between sensation and perception. For him, the spatiality of our sensations is not something superimposed by the “perceptions” of Helmholtz; rather, spatiality (or a sense for spatiality) is built into sensings themselves. Hence, sensations are not unorganized raw material, but sensing itself, as an activity, has access to spatiality as a primitive processes. Sensations being mental phenomena, even animals have perception in the strong sense of T2, although to a very limited extent in comparison with humans. In the manuscript “On the Soul of Animals” (Von der Tierseele, Ps 18), dated 1903, he even goes so far as to leave open the possibility of substances having mental activities (Brentano 1903. 50185–6). 24 UNITY AND TENSIONS IN AUSTRIAN PHILOSOPHY quality of what is given in sensations. Hering has no need for a further concept of perception as does Helmholtz, and can accommodate Müller’s law by simply adding that objectual space, the space of objects, is something that we think on the basis of our experience and of our inferences. We see the trees in a row of trees as being bigger from a short distance, and getting smaller at a greater distance, but we think them as being of relatively equal heights. Characterizing this “thinking” as a perception, as does Helmholtz, suggests that in vision itself, for instance, purely hypothetical thought-like processes are involved (e.g., Helmholtz’s unconscious inferences), a consequence rejected by Hering. Where does Brentano stand? Like Hering, Brentano seems to draw the conclusion that Müller’s law shows that a distinction between perception (of external objects) and sensation is superfluous. Sensations are specifically and spatially determined, and so is outer perception. According to him and similarly to Hering, I see the Müller–Lyer lines as being of equal lengths, but I think (or judge) them as being of unequal lengths. As far as outer perception is concerned, Brentano follows Hering’s reading of Müller and rejects the distinction between perception and sensation. But in contrast to Hering, Brentano still wants to argue for perception as a mental process different from sensation (sensory stimulations). This view is expressed in T2, in which perception (i.e. inner perception) is only of something that truly exists. This explains the restriction made that the only veridical perception is inner perception (i.e. the perception of one’s own mental acts). In other words, Brentano wants to stress the two following points. First, perception in the strong sense of T2 is not to be confused with the reception of sensory stimulation which we experience as physical phenomena. Second, the distinction between perception and sensation does not take place at the level of sensory stimulation and its processing (as Helmholtz would have it). Rather, sensings themselves already provide information about quality and localization; this information is not processed in a further step, called “perception” by Helmholtz. Therefore, in order to avoid misunderstanding, the term “perception” should be reserved for “inner perception”. At bottom, this second point seems more terminological than philosophical. Brentano made this exact point in 1889: The term “perception” has degenerated in an almost similar way [to the term “pleasure”]. Only really appropriate in respect of knowledge, it came to be applied in the case of the so-called external perception – i.e. in cases of a belief, blind, and in its essential relations, erroneous – and consequently would require, in order to have scientific application as a terminus technicus, an important reform of the usual terminology, one which would essentially narrow the range of the term (Brentano 1902. 83).18 18 The English translation here (and in many other places) uses “impression” instead of “perception” as a translation of Wahrnehmung. I have corrected the translation here. GUILLAUME FRéCHETTE: BRENTANO ON PERCEPTION 25 What this terminological remark suggests is that “perception” as a technical term simply covers too much. While Brentano prefers the traditional, Cartesian use of “perception” to designate cases of self-evident knowledge, and only such cases (the German Wahr-nehmung suggests it more clearly than its French or English equivalents), he does not deny that we have some kind of access to the external world. He simply points out a terminological confusion arising from the use of a single term to designate two different processes. This point should not be taken as denying any kind of access to the external world. What I have called above “sensory perception”, in the broader or naïve sense of openness to and/or awareness of the world is not challenged in any sense by this remark. But even if taken strictly in the terminological sense, Brentano’s remark is not without problems. First, the use of the term “perception” in late-nineteenth and early-twentieth century philosophy and psychology goes almost unanimously against Brentano’s suggestion. Even Brentano’s own students rejected the suggestion and used “perception” or “external perception” in the broader or naïve sense in which we used it above.19 Assertions like “strictly speaking, so-called external perception is not perception” (Brentano 1874/1973. 70), which soon became emblematic of Brentano’s conception of perception, should therefore be taken with a pinch of salt.20 In fact, the terminological remark on the use of the term “perception” seems not to be principled; rather, Brentano seems to stress in his later published works the terminological point against the use of “perception” by Helmholtz, Helmholtz’s student Wundt, and those who were influenced by them.21 In fact, in many texts Brentano does account for “outer perception” in terms which are quite comparable to those used to qualify perception as we are considering it here, as openness to and/or awareness of the world.22 He argues that by association we use the term “perception” both for cases of intuition (Anschauung) and for states which are characteristic of the occurrence of such intuitions.23 At 19 See for instance Stumpf 1939. 207 ff.; Bergmann 1908. 9 ff.; Marty 1908. 121; Twardowski 2016 [1895]. 201 ff. 20 One of the reasons why it received an emblematic character is certainly Husserl’s point in the Logical Investigations, in which he says, quoting this exact same phrase, that Brentano never should “have said of inner perception […] that it is really the only sort of perception in the true sense of the word” (Husserl 1901a/2001a. 239/345). 21 See for instance Brentano 2009 [1896]. 131, 148; [1897]. 51. 22 See for instance Brentano 1956 [ca.1884]. 144: “In outer perception, we are directed towards physical things, colours, sounds, smells, tactile qualities, etc. In short, towards something qualitative and sensory. Since it is something physical, it should be located (if it exists at all) in the external world. For this reason, we locate for instance a green colour, that we see, on a particular object of the external world, and we say that the tree is green” (my translation). 23 See Brentano (forthcoming: 53046): “By habitude, the name [perception] is closely associated with both the intuition under which it should properly be conceived and the different states which are typical for the occurrence of this intuition (since these states come always or most of the time along with this intuition)” (my translation). 26 UNITY AND TENSIONS IN AUSTRIAN PHILOSOPHY bottom, taking the background of his views in consideration, we can summarize Brentano’s views on perception with these three general ideas: (i) there is a general meaning of “perception” according to which it characterizes our openness and/or awareness of the world; (ii) inner perception is the only case of perception in which all cases of perception are cases of self-evident knowledge (and all these cases are exclusively cases of awareness); and (iii) outer perception is typically a case of perceptual experience in which physical things of the external world appear to us. All these cases are exclusively cases of openness. I will argue for the third idea in more detail in the next section. VI. PERCEPTION AND ILLUSION If we restrict the application of T2 to point (ii) mentioned above, it leaves open the possibility of accounting for perception in the naïve sense of openness and awareness of the world in Brentano’s conception. One obvious way of doing so would be to look at is conception of the physiology of perception. As I suggested above, Brentano’s position on psychology, physiology, and perception in general in the Psychology from an Empirical Standpoint is determined to a great extent by the natural sciences of his times. In Brentano’s case, it was the positivism of Comte that played the most important role. Scientific philosophy, in its “positive explanations – even if they were the most perfect ones – never claims to expose the producing forces of phenomena […] [it] simply seeks to analyse with exactness the conditions of their emergence and to connect these conditions through law-like relations of succession and similarity” (Brentano 1869. 23). Comte’s positivism was for him the reference model for the natural sciences, but it was not in principle incompatible with the Kantian idea of a scientific explanation in the form expounded by Helmholtz (1847), as Brentano himself concedes.24 In other words, what Brentano rejects in Kantian philosophy of science is its constructivism, especially as applied in Helmholtz’s concept of perception. Space is not a form of our intuition; it is a quality given in sensory perception. He would definitely reject the idea that “we can never perceive matter in itself, but only through its forces” (Helmholtz 1847. 4). In 1874, this attitude seemed to mean for Brentano that psychology as a science of the mental should restrict the talk of intentionality (the relation between the mind and the objects perceived) to the domain of inexisting objects; that it should restrict the talk of consciousness to the domain of mental phenomena; and that it should restrict the talk of perception (in the sense of evident knowledge) to the domain of mental phenomena. Restricting the talk of intentionality, consciousness, and perception (in the sense of T2) to the realm of the mental 24 See Brentano’s concession to Kant in Brentano 1874–1973. 128, fn2/76. GUILLAUME FRéCHETTE: BRENTANO ON PERCEPTION 27 seems, however, to be more a terminological restriction guiding the application of the right concepts to the right processes than the radical thesis often attributed to him that psychological knowledge does not apply to any other processes. It should therefore not be confused with the Kantian restriction of knowledge to phenomena. The former is motivated by the limits of our evident knowledge, while the latter is motivated by the alleged limits of knowledge tout court. That psychological knowledge applies to processes other than intentional acts, conscious acts, and perceptual acts in the sense of T2, is clear when Brentano talks about the “conditions of emergence” of mental and physical phenomena, which are also part of psychological investigation. In the 1880s, Brentano gave to the investigation of the conditions of emergence the label “genetic psychology”. That these investigations are not undertaken in the published version of the Psychology from an Empirical Standpoint has mainly to do with Brentano’s abandonment of the initial plan to publish a series of six books, which started with the Psychology as we know it, not with any principled concern about the object of psychology. The nature of mental and physical phenomena and their “conditions of emergence” are two different standpoints on objects that, eventually, could turn out to be identical.25 Sensations (or sensings, presentings, etc.) as mental phenomena are not necessarily objects that are distinct from those studied by physiology. They may even be the same objects studied from different perspectives. Nor does it necessarily follow, because sensory objects do not “truly exist” that they have no substantial role to play in understanding perception. As we pointed out earlier, it would also be wrong to think that Brentano would reject the distinction between subjective sensations (e.g., hallucinations) and objective sensations (externally stimulated sensations) simply because this distinction is not systematically accessible in inner perception (more on this below).26 Although descriptive classification has priority over genetic investigations in psychological research, it is not meant to override any genetic classification. In fact, when it comes to investigating the nature of perception, Brentano’s descriptive classification takes a surprising but revealing turn. Think of the explanation of the Müller–Lyer illusion that Brentano championed: on the face of it, his explanation follows the thesis defended by Helmholtz (1867. 566) of the perceptual overestimation of wide angles and the underestimation of narrow angles. But 25 Brentano was a dualist, but took great pains in developing a theory of the mind that could still be true if, by any chance, materialism turned out to be true. In his lectures on the immortality of the soul from 1875/76, he stresses the following point (Brentano 1875. 29586): “Therefore, one should always and in every case consider as a factual unity (sachliche Einheit) the totality of the mental activities that we innerly perceive. Thus the soul is not a collective, not a group of atoms of which we could apprehend the disintegration. Rather, from the standpoint of the hypothesis which we formulated, if the soul is material, then it is a unitary atom and thus, like all atoms, it is incorruptible” (my translation). 26 On this distinction, see Brentano 2009. 155 ff. 28 UNITY AND TENSIONS IN AUSTRIAN PHILOSOPHY this similarity is only superficial. Helmholtz’s model of explanation belongs basically to the category of physiological theories of illusions. Such models provide an explanation of the illusion on the basis of a disturbance in the information channels: it is merely the result of a physiological disturbance, which we describe as the overestimation of wide angles and the underestimation of narrow angles.27 While Helmholtz’s model is based on the supposition of physiological disturbances, Brentano’s model seems to be based on the supposition of an inappropriate application of the signalled information. Indeed, Brentano considers the Müller–Lyer illusion a case of “illusion of judgement” (Urteilstäuschung). In his view, this illusion of judgement is not to be confused with illusions “in which our phenomena do not correspond to the objectively given” (2009. 25). The broken stick illusion is such an illusion in the latter sense, and it is not an illusion of judgement, while the Müller–Lyer illusion is based on “a false evaluation of relations given phenomenally” (ibid.).28 The optical paradox emerges because the judgement that the lines are unequal conflicts with the initial phenomenon in which the lines are of equal lengths. It is quite remarkable here that both sorts of illusion presuppose a distinction between the objectively and the subjectively (or phenomenally) given. Müller– Lyer cases are such that the subjectively given actually matches the objectively given (two lines of equal lengths), but the paradox comes from the wrong judgemental evaluation of the subjectively given. In other words, the paradox comes from our rejection of (asubj. given= aobj. given), where a stands for the lines of equal lengths. Broken stick cases are such that the subjectively given simply does not match the objectively given; the paradox here comes from the acceptance of (bsubj. ≠ bobj. given), where b stands for the unbroken stick. In the first case, the paragiven dox arises only at the level of the judgement, while in the second case, it seems to come from a conflict which is intrinsic to the given itself. It is also quite remarkable that Brentano here uses the term “the given” (das Gegebene), which is quite unusual in his vocabulary. What he means by “objec27 On these theories, see Gregory 1970. 142, who labels them “physiological confusion theories”. 28 In the phenomenology lectures of 1888/89, Brentano is a little more explicit on this distinction: “[Optical illusions] are of two sorts: (1) of the sort like when a stick in water appears broken, or an object appears misplaced in a mirror. Here, we have a real modification of the phenomenon; but this modification is caused by light waves which make their way to me in an unusual manner from the body from which they are sent and make me conclude to the existence of the object. [In this case], habitude leads me to deceptive hypotheses on its position and form. If I contented myself in designating the phenomenon as a different one, I would make no mistake. (2) The cases are different when I deceive myself about the subjective phenomenon itself; when it appears to me for example modified in a certain way, while the phenomenon is unmodified. […] [This is the case with] the Zöllner figures. The appearance is so powerful that the modification of the phenomenon could barely be said to be more powerful. Even knowledge doesn’t suspend the appearance.” (Brentano-forthcoming-2. 59032.) GUILLAUME FRéCHETTE: BRENTANO ON PERCEPTION 29 tively given” and “subjectively given” is sometimes also described in terms of objective and subjective sensations. In his phenomenology lectures from 1888/89, he lists under subjective sensations the presentations of fantasy, but also the sensory feelings, the muscular sensations, reflex sensations, sensations of darkness, after-images, simultaneous contrast, and concomitant sensations. These sensations have a common and complex cause: they are the result of the conjunction, according to his student Marty, between innate and acquired dispositions.29 And most importantly, they are not caused by external stimulation. Only objective sensations are caused by external stimulation. Given this distinction, the Müller–Lyer case would be a case in which (a) I have an objective sensation of the lines as of equal lengths; (b) the subjectively given is identical with the objectively given; (c) I incorrectly reject the identity in (b). The broken stick case would be a case where (a) I have an objective sensation of the stick as unbroken, which (b) is not identical with the subjective sensation of the stick as broken and (c) I correctly accept that (a) and (b) are not identical. There are two obvious questions here. First, how do we know that objective sensations are always accurate (i.e. that the nerve signal which we experience as a physical phenomenon is produced by the appropriate external stimulation)? If objective sensations are always correct or appropriate signs of external reality, then we must admit that it is at least possible to directly perceive (in a relevant sense of “perception”) external reality (ordinary mind-independent objects), otherwise the distinction between objective and subjective sensations would be purely arbitrary. The second question is the following: is the distinction between objective and subjective sensation accessible in inner perception? If it is accessible, then I do have access in inner perception to the source of the stimulation. This would make T1, T2 and T3 false. T1 would be false because the external stimulation cannot be the target object of the intentional relation, and T2 and T3 would be false because if the distinction is accessible in inner perception, then inner perception would not be only perception of what truly exists (mental phenomena), and not only the perception of a mental phenomenon containing something (the physical phenomenon), but it would also give the correctness conditions of outer perception: an outer perception is correct when the external stimulation corresponds to the physical phenomenon, and it is incorrect when it does not correspond. If the distinction is not accessible to inner perception, then T1, T2, and T3 would be quite implausible or in need of serious improvements. T1 would be implausible if the possibility of perceiving external stimulation is granted. T2 29 See Marty 1889. Stumpf 1886 also uses the same distinction in his lectures on psychology. 30 UNITY AND TENSIONS IN AUSTRIAN PHILOSOPHY and T3 would not make much sense if one argues that there are correctness or accuracy conditions for outer perception which are not accessible to inner perception (correctness is, after all, something which one experiences in inner perception). If, in outer perception, we are able to discriminate between subjective and objective sensations, it would be implausible to hold that this ability to discriminate disappears in inner perception. What Brentano’s interpretation of the Müller–Lyer illusion suggests is that there are illusions, some of which (like the Müller–Lyer one) are illusions of judgement, but others emerge from a conflict between the subjectively and the objectively given. This distinction is incompatible with the central premise of the argument from illusion, which Robinson calls the phenomenal principle: Phenomenal principle: “If there sensibly appears to a subject to be something which possesses a particular sensible quality then there is something of which the subject is aware which does possess that sensible quality” (Robinson 1994. 32). In order for him to agree with the principle, he would have to abandon the thesis that in perceiving the stick in the water, the unbroken stick is objectively given to me. If his take on perceptual illusions gives us an important insight on his conception of the nature of perception, then T1–T3 are simply not a correct rendering of this conception and should be given up. VII. THE ALTERNATIVE TO THE STANDARD VIEW I believe that the grain of truth in the standard view of Brentano’s conception of perception consists in the two following claims: (1) Understanding perceptual processes in the right way presupposes knowing what is the nature of perception. Hence, descriptive psychology is prior to genetic psychology in the order of investigation. (2) In order to investigate the nature of perception, the best place to start is with inner perception, since all cases of inner perception are “good” cases: they show us things (i.e. mental phenomena) as they really are. However, we have seen here that these claims must be supplemented in order to conform with what Brentano actually says on perception: (3) Cases of inner perception should not be taken as paradigmatic cases of perception, as T2 suggests; they are simply instances of “good” cases. (4) There might well be cases of outer perception which could be included under the “good” cases30 – and there definitely need to be a few of them if 30 Nothing rules out that outer perception could be of something as it truly is: but if there are such cases, then these will not be cases of evident knowledge. GUILLAUME FRéCHETTE: BRENTANO ON PERCEPTION 31 the distinction between subjectively and objectively given is supposed to serve its purpose – but understanding cases of outer perception correctly is a far more complex task, since it requires an empirical investigation of their conditions of emergence. (5) Perception in the naïve sense of awareness, that is, in the sense that it sometimes gives us perceptual awareness of ordinary mind-independent objects, is not challenged by Brentano’s views. When I veridically see a blue patch, I have an objective sensation which is identical with the subjective sensation; when I see the broken stick in the water, I have an objective sensation of the unbroken stick. Having such a sensation presupposes, by definition, a regularity of the relation between the external object and the sign (the content of the objective sensation), which can be explained only if the possibility of having perceptual awareness of external objects is granted. (6) Perception in the naïve sense of openness, that is, the idea that in perceptual experiences we are presented with ordinary mind-independent objects, is not challenged either. The most basic form of perception is presentation (Vorstellung), and its presenting mind-independent objects is granted on the same basis as perception in the sense of awareness (5). If this alternative is correct, it seems that Brentano could agree with the intentionalist tenet that representations (or rather presentations, Vorstellungen in his terminology) present or represent at least partly in virtue of being more or less accurate. Such an interpretation, even if it means abandoning the standard view, would be welcome at least for a proper understanding of the motivations and details of Brentano’s descriptive psychology, of his realist ontology of his middle period, of his conception of time perception, and of his conception of mental dispositions.31 31 This is an expanded version of “Brentano on Perception and Illusion”, to be published in the proceedings of the 40th Kirchberg Symposium (C. Limbeck and F. Stadler eds.), which was given in Kirchberg, then in Munich and Guarapuava in 2017. The idea of this paper came from discussions with Marcello Fiocco in Salzburg in 2015/16 (see Fiocco 2017). I thank the Kirchberg audience for its input, especially those who took part in the workshop on Brentano and the Myth of the Given: Marcello Fiocco, Uriah Kriegel, Michelle Montague, and Hamid Taieb for stimulating interactions on the first version, Johannes Brandl for the discussions in Kirchberg and Munich, and Mark Textor for his input in Munich. Thanks also to Evandro Brito, Ernesto Giusti, André Leclerc, Mario Gonzáles Porta, Gleisson Schmidt, Jean Siqueira, Wojciech Starzyński, and the other participants at Universidade Estadual do Centro-Oeste do Paraná (Guarapuava) for stimulating discussions during the Brentano conference there. This paper was written as part of the research project “Brentano’s Descriptive Psychology” funded by the Austrian Science Fund (FWF, P-27215). 32 UNITY AND TENSIONS IN AUSTRIAN PHILOSOPHY REFERENCES Bergmann, Hugo 1908. Untersuchungen zum Problem der Evidenz der inneren Wahrnehmung. Halle, Niemeyer. Brentano, Franz 1867. Die Psychologie des Aristoteles. Mainz, Kirchheim. Brentano, Franz 1869. Auguste Comte und die positive Philosophie. Chilianeum. 2. 16–37. Brentano 1874/1973. Psychologie vom empirischen Standpunkt. Leipzig, Hirzel. English trans. Psychology from an Empirical Standpoint. London, Routledge. Brentano, Franz 1875. Unsterblichkeit. Kolleg 1875/76. Unpublished lecture notes. Houghton Library, Harvard University (LS 22). Brentano, Franz 1894/95. Positivismus. Kolleg 1894/95. Unpublished lecture notes. Manuscript O. Kraus. Prague, Masaryk Archives (Kraus IIIa19). Brentano, Franz 1902. The Origin of the Knowledge of Right and Wrong. Westminster, Constable. Brentano, Franz 1903. Von der Tierseele. Unpublished Manuscript. Houghton Library, Harvard University (Ps 18). Brentano, Franz 1956. Die Lehre vom richtigen Urteil. Hamburg, Meiner. Brentano, Franz 1975 [1916].Was an Reid zu Loben ist. Grazer Philosophische Studien. 1. 1–18. Brentano, Franz 1979. Untersuchungen zur Sinnespsychologie. Hamburg, Meiner. Brentano, Franz 1988.Über Ernst Machs “Erkenntnis und Irrtum”. Amsterdam, Rodopi, 1988. Brentano, Franz 2009. Schriften zur Sinnespsychologie. Frankfurt, Ontos. Brentano, Franz forthcoming. Deskriptive Psychologie: Vorlesungen 1887/88. Dordrecht, Springer. Brentano, Franz forthcoming-2. Phänomenologie und Psychognosie: Vorlesungen 1888/89 und 1890/91. Dordrecht, Springer. Caston, Victor 2001. Connecting Traditions: Augustine and the Greeks on Intentionality. In Dominik Perler (ed.) Ancient and Medieval Theories of Intentionality. Brill, Leiden. 23–48. Chisholm, Roderick 1967. Intentionality. In Paul Edwards (ed.) Encyclopaedia of Philosophy. London, MacMillan. Crane, Tim 2009. Intentionalism. In Ansgar Beckermann – Brian McLaughlin (eds.) Oxford Handbook to the Philosophy of Mind. Oxford, Oxford University Press. 474–493. Crane, Tim 2009a. Is Perception a Propositional Attitude? The Philosophical Quarterly. 59. 452–469. Crane, Tim 2013. The Objects of Thought. Oxford, Oxford University Press. Crane, Tim – French, Craig 2016. The Problem of Perception. In The Stanford Encyclopedia of Philosophy. https://plato.stanford.edu/entries/perception-problem (consulted on March 15, 2018). Descartes, René 1902. Oeuvres de Descartes: Vol. 4. Discours de la méthode & essais. Charles Adam, Paul Tannery (eds.). Paris, Cerf. Fiocco, Marcello 2017. Knowing Things in Themselves. Mind, Brentano, and Aquaintance. Grazer Philosophische Studien. 94. 332–358. Fisette, Denis 2011. Brentano et Husserl sur la perception sensible. Bulletin d’analyse phénoménologique. 7. 37–72. Føllesdal, Dagfinn 1969. Husserl’s Notion of Noema. Journal of Philosophy. 66. 680–687. Fréchette, Guillaume 2017. Brentano on Content and Object. IfCoLog: Journal of Logics and their Applications. 4/11. 3609–3628. Gregory, Richard 1970. The Intelligent Eye. London, Weidenfeld and Nicolson. Heidegger, Martin 1992 [1925]. History of the Concept of Time. Prolegomena. Bloomington, Indiana University Press. Helmholtz, Hermann 1847. Über die Erhaltung der Kraft, eine physikalische Abhandlung. Berlin, Reimer. Helmholtz, Hermann 1867. Handbuch der physiologischen Optik. Leipzig, Leopold Voss. GUILLAUME FRéCHETTE: BRENTANO ON PERCEPTION 33 Helmholtz, Hermann 1878. Die Thatsachen in der Wahrnehmung. In H. Helmholtz, Vorträge und Reden. Vol. 2. Braunschweig, Vieweg. 217–271. Hickerson, Ryan 2007. The History of Intentionality: Theories of Consciousness from Brentano to Husserl. London, Continuum. Hume, David 1748. Philosophical Essays Concerning Human Understanding. London, Millar. Husserl, Edmund 1901. Logische Untersuchungen. Band 1. Halle, Max Niemeyer. Husserl, Edmund 1901a. Logische Untersuchungen. Band II, zweiter Teil. Halle, Max Niemeyer. Husserl, Edmund 2001. Logical Investigations. Vol. 1. London, Routledge. Husserl, Edmund 2001a. Logical Investigations. Vol. 2. London, Routledge. Jacquette, Dale 1990. The Origins of Gegenstandstheorie: Immanent and Transcendant Intentional Objects in Brentano, Twardowski, and Meinong. Brentano Studien. 3. 277–302. Jacquette, Dale 1996. Alexius Meinong (1853–1920). In Liliane Albertazzi – Massimo Libardi – Roberto Poli (eds.) The School of Franz Brentano. The Hague, Kluwer. 131–159. Jacquette, Dale 2006. Brentano’s Concept of Intentionality. In Dale Jacquette (ed.) The Cambridge Companion to Brentano. Cambridge, Cambridge University Press. 98–130. Marty, Anton 1889. Genetische Psychologie (unpublished lecture notes). Leuven, Husserl Archives (Q 10). Marty, Anton 1908. Untersuchungen zur Grundlegung der allgemeinen Grammatik und Sprachphilosophie. Halle, Niemeyer. Massin, Olivier 2017. Brentano on Sensations and Sensory Qualities. In Uriah Kriegel (ed.) The Routledge Handbook of Brentano and the Brentano School. London, Routledge. 87–96. McDowell, John 1994. Mind and World. Cambridge/MA, Harvard University Press. Müller, Johannes 1837. Handbuch der Physiologie des Menschen. Vol. 2. Koblenz, Hölscher. Mulligan, Kevin 2004. Brentano on the Mind. In Dale Jacquette (ed.) The Cambridge Companion to Brentano. Cambridge, Cambridge University Press. 66–97. Price, Henry Habberley 1932. Perception. London, Methuen. Reid, Thomas 1895 [1764]. An Inquiry into the Human Mind on the Principles of Common Sense. In W. Hamilton (ed.), The Works of Thomas Reid D.D. Vol. 1 (8th edition). Edinburgh, James Thin. 95–211. Robinson, Howard 1994. Perception. New York, Routledge. Seron, Denis 2017. Brentano on Appearance and Reality. In Uriah Kriegel (ed.) The Routledge Handbook of Brentano and the Brentano School. London, Routledge. 169–177. Seron, Denis 2017a. Brentano’s Project of Descriptive Psychology. In The Routledge Handbook of Brentano and the Brentano School (ed. Uriah Kriegel). London, Routledge. 35–40. Smith, Barry 1994. Austrian Philosophy. The Legacy of Franz Brentano. Chicago, Open Court. Smith, David 2002. The Problem of Perception. Cambridge, Harvard University Press. Stumpf, Carl 1886. Vorlesungen über Psychologie (unpublished lecture notes). Leuven, Husserl Archives (Q 11). Stumpf, Carl 1939. Erkenntnislehre Vol. 1. Leipzig, Barth. Textor, Mark 2007. Brentano on the Doxastic Nature of Perceptual Experience. Logical Analysis and History of Philosophy. 10. 137–156. Textor, Mark 2017. Brentano’s Mind. Oxford, Oxford University Press. Twardowski, Kasimir 2016[1895]. Logik: Wiener Kolleg 1894/95. Berlin, De Gruyter.