Caging The Striped Tiger, The Lies of Descriptionalism Markel Kortabarria Areitio APhil Master, Philosophy and Cognitive Science markelkor96@gmail.com Abstract: Throughout the last fifty years two theories have been championed within the mental imagery debate. On the one side, pictorialists like Fodor (1975) and Kosslyn (1980) defended the view that mental representations ressemble non-mental images in that they are both depictive representations. On the other side, descripionalists such as Dennett (1969) and Pylyshyn (1973) argued that mental images represent propositonally through descriptive sentences. During those years many arguments were presented, discussed and refuted. The aim of this paper will be to analyze one of the main arguments that was wielded against the pictorialist view, namely Dennett's striped tiger objection. The objection holds that the inherent indeterminacy of mental images with respect to visual properties shows that mental representations could not be pictorial, and thus the content of mental representation needs to be different from the content of perception. My purpose will be to show that Dennett's argument is incorrect and falls prey to what Block (1983) identified as the photographic fallacy. After doing so I will argue that descriptionalists often overlook fundamental features involved in the exercise of our imaginative faculties misconceiving the way in which subjects perceive, imagine and determine phenomenical properties. Eventualy I will align with Nanay's (2014) defense of the similar content view and the determinability thesis. Key Words: Pictorialism, descriptionalism, mental imagery, representations, imagination, photographic fallacy, phenomenical properties, determinability. 1. The State of Play Interest in the debate about the format underlying mental representations arose during the 70's after the 'cognitive revolution'. Throughout those years two theories stood out within the mental imagery debate. Pictorialists, mainly represented by Kosslyn (1980), contended that our mental representations are better understood in analogy to our perceptual experience of nonmental images. The subjective experiences we undergo when experiencing mental imagery are best characterized in terms of mental pictures. Unconvinced by this approach, descriptionalists such as Dennett (1969) and Pylyshyn (1973) offered an alternative view. They held that the underlying representational structure of mental imagery is based on our propositional knowledge concerning visual properties. In short, descriptionalits argued that there is nothing really depictive going on in the sense pictorialists claimed, instead, mental representations were said to represent through purely linguistic mechanisms. Pictorialism derived much of its appeal from the well known experiments involving rotation and map scanning. However, empirical research done in the area of artificial intelligence also supported descriptionalism. The experiments concerning mental rotation were introduced by Shepard & Metzler (1971). The results found that when subjects were asked to mentally rotate images until they fited some possible answer the time taken to confirm that both objects were identical increased in relation to the angular difference. This was taken to be a clear evidence in favor of pictorialism. In Kosslyn, Ball, & Reiser's (1978) mental scanning experiments subjects were showed to be able to generate a highly accurate mental representation of an already seen map. The result demonstrated a direct connection between response latency and the visually scanned distance. On the side of descriptionalism Pylyshyn (1978) extended his defense of structural descriptionalism and argued against the Shepard & Metzler experiments. He presented some emerging notions from the artificial intelligence research concerning symbol systems and the computational representation of the spatial 1￼. The dispute between pictorialists and descriptionalists has generated considerable literature and many arguments have been put forward and against both theories. The goal of this paper is to analyze one of the main arguments presented against pictorialism, namely Dennett's Striped Tiger objection2. In section seven of "Content and Consciousness" Dennett argued that the inherent indeterminacy of mental representations with respect to some visual properties (such as stripes) showed that the content of imagery could not be pictorial. The alledged reason was that usually imagination lacks detail as regards to the determinacy of phenomenical properties in perceptual representations. Otherwise said, Dennett held that when imagining a tiger we do not picture it as having a determinate number of stripes, whereas an actual picture of a tiger must be determinate about stripeness3. Descriptionalism was said to be able to accomodate the indeterminacy of mental imagery and Dennett's counterexample was supposed to offer a compelling reason in its favour. My purpose in this essay is rather humble, I intend to cage Dennett's tiger by showing that his account of pictorialism overlooks some relevant features involved in the exercise of imaginative faculties. Of course, attempts to undermine this counterexample are not new, Hannay (1971) and Fodor (1975) offered responses in terms of the blurry and evanescent nature of mental imagery. They both argued that mental images are not indeterminate in the sense Dennett sustained. In fact, as we will see, Dennett's argument erroneously assumes that pictorialism holds a photorealistic account of mental imagery. He seems to think that 1 This paper does not intend to go into the vast sea of empirical work in cognitive science. Such a task lies beyond scope. Rather, I intend to philosophically contribute to the mental imagery debate by conceptually disbanding one of the main assumptions descriptionalist make. In this sense my work remains empiricaly neutral and pretends to be compatible with the results derived from the aforementioned studies. Having said this, it is difficult to ignore the fact that the results related to the Shepard & Metzler experiments remarkably illuminated the debate, yielding very significant data on the similarity between mental and perceptual content. Furthermore, work in artificial intelligence is still taking off and the few advances that have been made already show results that conflict with some of the descriptivists theses. 2 Variants of this argument may also be found in Armstrong's (1968) speckled hen example and Shorter's (1952) man with a hat , which is also mentioned in Dennett (1969) and analyzed in Block (1983). 3 Note that what is in play here is what Dennett calls 'the rules of images in general'. However, as we will see, the mental imagery debate does not concern the instantiation of phenomenological properties, instead it is a matter of the phenomenological determinability of those properties to wich the mind can aspire when performing imaginative tasks. More on this on next section. pictorialists do not compare but equate perceptual and mental content. Hence, ultimately the striped tiger objection presents a distorted version of pictorialism, commiting what Block (1983) sagaciously labelled the photograpic fallacy. However, my intention is to go one step further and argue that even though the content of imagination and perception is structuraly the same, there is an important difference in how that content comes about. For this I will be basing my argument on Nanay's (2014) defense of the similar content view in terms of the determinability of phenomenical properties. I will focus the debate on a point that has been severely overlooked, the fact that imagination attempts to mirror perception but never completely succeeds. This in turn will offer us a satisfactory explanation of how mental images are typically experienced as phenomenically impoverished in relation to their perceptual counterparts while keeping the similar content view intact. 2. Hunting Dennett's Tiger To begin with let us unleash Dennett's descriptionalist beast: Consider the Tiger and his Stripes. I can dream, imagine or see a stripped tiger, but must the tiger I experience have a particular number of stripes? If seeing or imagining is having a mental image, then the image of the tiger must – obeying the rules of images in general – reveal a definite number of stripes showing, and one should be able to pin down with such questions as 'more than ten?', 'less than twenty?'. If however, seeing or imagining has a descriptional character, the questions need have no definite answer. Unlike a snapshot of a tiger, a description of a tiger need not go into the number of stripes at all; 'numerous stripes' may be all the description says. Of course in the case of actually seeing a tiger, it will often be possible to corner the tiger and count his stripes, but then one is counting real tiger stripes, not stripes on a mental image.4 Dennett holds that since mental images are indeterminately depictive they could not be pictorial in the way pictorialists argue. The reason is that while mental images can be inexplicitly noncommittal, pictorial representations can only be so explicitly. What does this mean? According to Block representations are committal regarding a property F in that they represent something either as having F or as not having it. If a representation does not go in to the matter of F it is said to be inexplicitly non-committal about F. In contrast, a representation is explicitly noncommittal in regard to F if it represents something in a way that precludes commitment to the property of F. In simpler terms a mental representation of a tiger is inexplicitly non-committal about the number of stripes because it refuses to go into the detail of stripeness. Opposedly, a perceptual representation of a tiger is explicitly non-committal because – following the rules of images in general it could only avoid stripeness by explicitly precluding it (a painting of a tiger lurking behind a tree could hide the stripes making them uncountable in the same way an intentionally overexposed photography would be too blurry to make the counting successful). Dennett's point is that when we imagine a tiger we do not imaging it as having a determinate number of stripes, the inexplicit non-commitment of mental imagery comes from the inherent indeterminacy of its content. Thus, insofar as an image cannot be inexplicitly non-committal in regard to some of its visual properties mental images are not really images. 4 Dennett (1969) pg. 136-137. Italics on the original. I think a couple of things could be said. Let's begin with Dennett's account of pictorialism. Dennett seems to be assuming a way of understanding pictorialism that has been incorrectly attributed to the defenders of this theory, namely, that the phenomenical character of mental imagery is entirely analogous to its perceptual counterpart. Block identified this as the photographic fallacy of descriptionalism5. First of all, whatever 'the rules of images in general' are, perceptual representations can be inexplicitly non-committal. An impressionist painting of a tiger, the sketch of a nine year old child or an unintentionally blurred photography could fail to represent the stripes of a tiger determinedly, but would still represent the tiger depictively. Furthermore, even in the case of witnessing an actual tiger it would be possible to perceive it on an inexplicitly non-committal way. The feline might have been seen out of the corner of the eye, after being dazzled or simply in too short a period of time to perceive a fully determined representation. In these cases the perceptual representations would also be indeterminate in regard to some of its phenomenical properties in an inexplicitly non-committal way. Thus, content similarity still holds. Having said this, I think that Dennett's skepticism about the existence of qualia could be clouding his judgement concerning the imagery debate. Dennett demands that both mental images and their phenomenical properties need to be concrete, determinate and straightforward. But truth is they need not. Our subjective experiences of phenomenical properties do not only include the clear and hyperdetermined properties that Dennett insists on. Complete determination is not a necessary condition of perceptual experience. Negating the existence of mental imagery based on the existence of inaccurately determined phenomenical properties is severely misconceiving not only the nature of imagination, but of perception itself. A subject suffering from alcoholic intoxication might experience perceptual representations in a fuzzy and blurry way. In the same way a person experiencing an ambiguous image of a tiger is still experiencing a perceptual representation of a tiger. Moreover, Dennett's criticism is in danger of denying representations of any kind to people who suffer from disabilities that prevent them from perceiving things as accurately as possible. No one would claim that the representations perceived by people suffering from myopia, mild blindness or daltonism are not to be counted as such just because they lack high determination6. Subjective perceptual experiences do not need to be unambiguous and sophisticated to be counted as perceptual experiences. Someone could try to push the point arguing that blurriness is a bit off when we are dealing with the content of mental imagery. When we see something in a blurry and fuzzy way we experience it as lacking information. However, when imagining something the phenomenology is not as of something being imperfectly experienced. Such an objection attempts to re-establish the distinction between mental and perceptual content. My answer connects directly with the following section, so let me be brief. Simply put the indeterminacy of the mental images, as well as that of the perceptual ones, comes from the lack of information. The important thing here, and what establishes the distinction between the format of imagery and perception, is where this lack of information comes from. While perception extracts information and determination from the world, imagination extracts it from memory. This justifies the evanescent nature of mental imagery while keeping the structural similarity between the 5 In fact, Block carried his objection beyond Dennett's counterexample arguing against Pylyshyn's example of young children's misrepresentation of beaker's containing fluids. For more on this interesting issue I recommend reading Block (1983). 6 Here restrict my comment on subjective experiences to visual properties but truth be told I believe this account could be applied to every type of subjective experiences and their imaginary counterparts. In fact, if this were not the case we would not be coming up with an adequate theory of mental imagery for it would exclude many of the subjectively experienced properties we usually count as mental imagery. content of the mental and perception. But let's not rush into conclusions and let us see this in more detail. 3. Determinability and phenomenical properties Now that Dennett's objection has been dismissed it is time to inquire into the matter of determinability. In section one I claimed that despite the fact that the content of imagination and perception is structurally the same, there is an important difference in how that content comes off. In this section I want to consider how the cognitive mechanisms we deploy during visualization make it the case for the distinction between mental imagery and perceptual experience without abandoning the similarity thesis. Specifically, I want to contend for the position that imagination attempts to mimic perception and its determination mechanisms but it never completely succeeds. In other words, I grant that the content of imagination and perception is structurally the same, however, I believe, along with Nanay (2014), that there is an important difference in how the determinacy of that content is established. To illuminate this matter let us return once more to Dennett's example. In the last lines of the fragment above Dennett adds that in the case of seeing an actual tiger it is possible to count the stripes if one approaches the animal and focuses his attention on the arduous task of identifying and individuating each line. Initially this may seem like a trivial claim, it is insubstantially obvious that one could count the lines on a tiger's fur (assuming that clear distinct stripes could be seen on a tiger). However, note that by approaching the tiger, surrounding it and focusing on the stripes one is determining a visual property through purely perceptual mechanisms. My claim is that one could attempt to make this very same property determinate on an imaginary tiger by mentally mimicking those perceptual mechanisms. In fact, this is precisely what we do when we undergo imaginative processes such as 'zooming in', 'rotating' or 'individuating bits'7. I will return to this later, for now let's keep with how property determination comes about in perceptual representations. In "Perceptual content and the content of mental imagery", Nanay offers what I believe is a clear and accurate explanation. According to him , perceptual content is constituted by the sum of properties that are perceptually attributed to the perceived scene8. Our perceptual apparatus attributes different properties to various parts of the perceived scene. When assessing Dennett's example we have seen how phenomenical properties in perceptual representations can also be undetermined in a inexplicitly non-committal way. I would say that it is a fairly accepted fact that determinacy comes in degrees, a perceived property can be experienced as more or less determinate depending on how clearly it has been perceived. However, determinacy also comes in scale. Some of the properties we perceptually attribute to the representations we experience are determinate whereas others are determinable. As Nanay points out, the property of being red is determinate of the property of being colored but 7 Furthermore, the results of Shepard & Metzler and Kosslyn, Ball, & Reiser experiments concerning mental rotation and scanning strongly supported the claim that perceptual mechanisms involved in imaginative tasks structuraly ressemble their perceptual counterparts at a very deep level of similarity. 8 I believe that, in addition to properties, relations also play an important role when it comes to representing. I guess that an ardent defendent of descriptionalism could argue that relations imply propositional content which in turn imply descriptional content. Howbeit, this makes little difference in relation to the idea I am trying to defend here since relations appear to come complementing properties in the way Fodor (1975) argued. determinable of the property of being scarlet9. This in turn, reflects upon the similar content view of pictorialism, for similarity between the content of perception and mental imagery is not a matter of determination of properties but of their determinability. An example will better illuminate the matter: While I'm writing this I have in front of me, on my desk, a copy of Dante's marvelous "The Divine Comedy". If, as it is now the case, I am not paying much attention to the book some of its properties will only be perceived as poorly determined. For example, I might attribute the properties of being wrapped in a redish bookbinding, of having some golden lettering on it and perhaps, of having some drawings on it10. Now, if for some minutes I stop writting this essay and instead I completely focus my attention on the book, some of the perceived properties will instantly acquire a higher degree of determinacy. The colour might begin to look more crimson than redish, the lettering on the cover will be perceived more determinedly allowing me to read the tittle of the book, and if I focus my attention on the engraving I will notice that what was before perceived as a scribble is now a beautiful drawing of hell's gate. In conclusion, Nanay is right, attention is the means by which our perceptual system determines the properties of a given representation. When attention is less than optimal we only attribute determinable properties, as we focus properties become more determined. Having said this, how does this affect the way in which properties are ascribed in mental representations? Well, imagery is also cumulative in the sense that we mentally attribute various properties that build up our representations. Previously I claimed that imagination attempts to mirror perception but it never completely succeeds. This is made evident in light of the book example, if the content of mental imagery resembles the content of perceptual experiences, properties should be ascribed analogously. Thus, when imagining Dennett's tiger, some of the properties we imagine (colour, size, particular forms and shapes, etc) are primarily determinate while others (stripes, eye colour, the exact colour and pathing of the fur, etc) are determinable. Just as in perception attention attempts to make the imagined properties more determinate and it is in this sense that imagination mechanically mimics perception. The fundamental difference concerns where determinacy comes from. In the case of perceptual experience determinacy of properties comes from perception itself, the degree of determination is guaranteed by our perceptual mechanisms and the world in itself11. However, as Nanay notes, 9 Nanay's analysis seems to imply that there might even be superdeterminable properties which are the ones upon which the other properties are determined. I suspect that such properties would include some kind of primordial qualia, things such as colourness, geometrical form and location are some of the immediate candidates I can think of. In facr Nanay argues that the determinable-determinate relation suggests a hierarchical ordering in which properties with no further determinates would be considered, if existent super-determinates. 10 However, it is important to note that each of the ascribed properties require all of some level of attention. It could very well be the case that for some reason, let's say that the book is on one side of my desk instead of in front of me, my attention was even less focused on it. In which case, some of these properties would be experienced as even less determinate (for example I could be perceiving the book as just being colored) or would just be unexperienced at all (I could fail to make determinate the lettering). 11 One of the things I thought of when considering how determinacy is confered both in perceptual representations and mental imagery is the role of steadyness. When experiencing a perceptual representation of a tiger steadiness helps us in determining its properties. However, when it comes to mental imagery, steadiness is at odds with the evanescent nature of mental images in the sense that it requires of some cognitive effort to hold an object in mind. Perceptual representations are externally static whereas mental ones are internally so. This supports my idea that qualitatively pairing perceptual processing and manipulation of non-mental images with mental ones is misconceiving human imagination. Which again brings us back to Block's photographic fallacy. For an interesting insight about this idea see Lyons (1984). when it comes to mental imagery determinacy is extracted from perceptual memory. This is where the difference in content becomes apparent. Even though visual memories bear perceptual knowledge, they do not constitute perceptual input. This is precisely why imagined scenes reveal themselves as perceptually poorer. As far as Denett's tiger is concerned, we are unable to count the stripes because imagination is unable to fully emulate perception. This is because the means by which imagination attempts to determine phenomenological properties differ from the way perception does. Imagination emulates perception, making its content structurally similar as well as constitutively different. 4. Conclusion So far we have considered the striped tiger objection, we have showed how the objection falls prey of the photographic fallacy and how it misconceives the pictorialist account. In the second section we argued in favor of the similar content view claiming that although mental representations can be considered undetermined in regard to some of their properties, the same applies to perceptual representations. We claimed that whatever the rules of images in general are, perceptual representations can be inexplicitly non-committal and argued that the similarity between the content of mental imagery and perception still remains. Additionally, we stated that this similarity is not a matter of the inherent determination of properties but of our capacity to make those properties determinate through our perceptual and imaginative mechanisms. In the third section we explored this claim in more detail introducing Nanay's distinction between determinate and determinable properties and showed how this applies to perceptual representations. Ultimately we argued that attention is the mechanism through which the perceptual system attempts to determine the determinable properties. The fact that this mechanism is cognitively mimicked in mental imagery offers a compelling reason in favor of the pictorialist view. However, in spite of the alleged similarity there is a fundamental difference between the content of perception and mental imagery that has been severely overlooked. This difference concerns the way and the extent to which determinacy is conferred in imagination. In the case of perception determinacy is extracted from perceptual input, whereas imagery draws it from perceptual memory. 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