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Experience and Sensation

 Sellars and Dewey on

the Non-cognitive aspects of Mental Life.

Published in "Education and Culture: the Journal of the John Dewey Society" Winter, 2001



Sellars and Dewey each isolated and critiqued different aspects of the atomistic epistemology of the logical positivists:  Dewey labeled his target "Sensationalistic Empiricism", and Sellars labeled his "the Myth of the Given."  The main theme of this paper will be the similarity and differences in their responses to this kind of philosophy, and how both responses can be clarified and strengthened by considering recent discoveries in Cognitive Neuroscience. What we have recently learned about  neural architecture accounts for a distinction between knowledge and experience that is a recurrent theme in both Sellars and Dewey. Dewey, however, made a sharper break from the positivists by seeing all experience as shaped by skills and abilities which were designed to acheive certain goals and were colored by emotions. The connectionist architecture used in Cognitive Neuroscience supports this view, as does the psychological research of J.J. Gibson. Once we consider the ways in which connectionist cognitive abilities differ from linguistic ones, Sellars' distinction between thoughts and sensations, and Dewey's distinction between knowledge and experience, can both be plausibly accounted for.





            Sellars never used the word 'experience' as a technical term the way Dewey did,  and to my knowledge never cited Dewey's epistemology when discussing his own. But they were both interested in coming up with an holistic alternative to the atomistic epistemology of Bertrand Russell, G.E. Moore, and C.D. Broad.  Sellars and Dewey each isolated and critiqued different aspects of this atomistic epistemology by giving it a name: Dewey labeled his target Sensationalistic Empiricism, and Sellars called the object of his critique the Myth of the Given.  The main theme of this paper will be the similarity and differences in their responses to this kind of philosophy, and how both responses can be clarified and strengthened by considering recent discoveries in Cognitive Neuroscience.


            Shortly after Dewey's death, it appeared that his critiques of Sensationalistic Empiricism had been unsuccessful (at least in the academic marketplace). The twentieth century empiricism that called itself  "analytical philosophy" eventually replaced Deweyan pragmatism in America, and various related theories of knowledge with names like "Sense datum theory", "Logical Positivism," and "Logical Empiricism" made an orthodoxy out of the view of knowledge that Dewey had tried so hard to defeat. Now, however, this kind of empiricism is in disrepute, thanks to critiques made primarily by Quine and Sellars, of what Sellars called the Myth of the Given. Sellars' critique of sense datum theory in  his "Empiricism and the Philosophy of Mind", and Quine's critique of the empiricist dogma that  it is possible to reduce all meaningful statements to inferences from directly given observation sentences, has made a new orthodoxy out of the belief that sensationalistic empiricism is a dead horse no longer worth beating.


            But does the defeat of sensationalistic empiricism imply a triumph for the alternative theory of experience that Dewey proposed in works like "Experience and Nature"? Quine, at least, speaks favorably of Deweyan pragmatism as the wave of the future, as do Rorty, Putnam and many others. But Rorty seems to express the modern attitude when he says that "the philosophers of today . . .  tend to talk about sentences a lot but say very little about ideas or experiences" (Rorty 1994 p. 55). Quine certainly exemplifies this attitude when half way through "two dogmas of empiricism", he decides to sidestep the questions of what an observation is, and concentrate instead on observation sentences. The fact that he proudly described himself as a behaviorist, and spent a great deal of time attacking anything that might be describable as mental, makes it highly unlikely that he would be sympathetic to any talk about something called "experience". But Sellars, although he refers to himself as a " verbal behaviorist", and considers knowledge to be primarily linguistic, has a fair amount to say about the non-linguistic aspects of experience. Unlike Quine, he emphasized that it was necessary to talk about inner events, not just behavior and language. 


Sellars and Sensations


            Sellars claimed that there were inner events he called "sensations" or "sensa" , which seems to suggest a close kinship with sense data. But he also avoided many of the mistakes of sense datum theory by turning the concept of sensation on its head, making it a theoretical concept rather than something immediately given. Once the supposedly essential characteristic of givenness is removed from sensations, what is it that we have left, exactly? There are many indications that Sellars sometimes thought that sense data do exist, with almost all of the attributes that Broad, Moore and Russell ascribe to them except for givenness.


I am sketching a view which hovers on the edge of the sense datum theory, and yet I believe it succeeds in avoiding falling into the abyss. (Sellars 1989 p.103)


 For Sellars, sensations are non-cognitive, because having a sensation is distinct from knowing about it. They are also non-linguistic, because thinking "there is a pink ice cube" is phenomenologically different from sensing a pink ice cube. Sensations are described as "self-presenting'  (ibid. p. 282), even though they must be accompanied by a cognitive mental event for us to be aware that they are presenting themselves.[1] And once we do know about them that knowing is considered to be "non-inferential".  Unfortunately all of these descriptions are largely negative, and although there are many attempts by Sellars to describe this kind of knowing in positive terms, they are considered by many to be "one of the most difficult and controversial aspects of his philosophy." (Rosenberg 1997)


            Sellars, like most  Analytic and Post-Analytic Philosophers, embraced the assumption that questions about knowledge and thought are primarily questions about language. But unlike most of his contemporaries, he was also aware of the limitations of this assumption. In the following quotation, Sellars almost admits that there is something wrong with his approach, without actually suggesting that there is any other way of dealing with these questions.


Not all 'organized behavior' is built on linguistic structures. The most

that can be claimed is that what might be called 'conceptual thinking'

is essentially tied to language, and that, for obvious reasons, the

central or core concept of what thinking is pertains to conceptual

thinking. Thus, our common-sense understanding of what sub-conceptual thinking -- e.g., that of babies and animals -- consists in, involves viewing them as engaged in 'rudimentary' forms of conceptual thinking.  We interpret their behavior using conceptual thinking as a model but  qualify this model in ad hoc and unsystematic ways which really amounts  to the introduction of a new notion which is nevertheless labeled thinking'. Such analogical extensions of concepts, when supported by experience, are by no means illegitimate. Indeed, it is essential to science. It is only when the negative analogies are overlooked that the danger of serious confusion and misunderstanding arises. (Sellars 1975 p.305)



            Another quotation, however, actually points towards another approach which was eventually embraced by many of his students.


"the notion of sense data or sensation itself is really a part of a scientific theory of perception, not a philosophical theory. . . Philosophers often have to rush in where behaviorists fear to tread. " (Sellars 1989 p. 119 ).



            Since Sellars said those words,  psychologists, neuroscientists and philosophers have all rushed in where behaviorists had feared to tread, for behaviorism (and it's fear of opening the black box that underlies human behavior and experience) is now as dead in  psychology as sense datum theory is in philosophy. And this willingness to inquire into the mechanisms underlying thought has naturalized philosophy to a degree that often blurs the line between philosophy and science. One of Sellars' students who leads this naturalized philosophy movement is Ruth Millikan, who appears to have taken both of the above paragraphs to heart in Millikan 1984. Instead of trying to understand animal abilities by simply making analogies with human language-centered thought, she formulated a whole new theory that saw both animal and human cognition as members of more fundamental biological categories.  The bare beginnings of that theory seem to be prophesied in Sellars 1981, which even uses Millikan's paradigmatic bee dances as an example of  an animal representational system.  Another important Sellars student, Paul Churchland,  started a philosophical movement by extensively analyzing the philosophical implications of the newest neurological data, and defending the claim that because thought is fundamentally neurological, to conceive of it as linguistic is at best misleading and worse false. This is a possibility that was left open in Sellars 1981 when he said that although language is "our primary concept of thinking, and therefore our conceptual point of entry into our domain of the mental"  it was not primary in the order of being (p. 327). In other words,  a careful study of neuroscience could reveal that the ultimate nature of thoughts is as different from language as tables and chairs are different from electrons. And it would not be surprising that sensations, which are the big puzzle in a linguistically based theory of mind, would be more comprehensible in a neurologically based one.


            We can thus see that there is good reason to think that a study of modern Cognitive Neuroscience could be helpful in clarifying Sellars' epistemology. Is there any reason to think this would also be true of Dewey's epistemology as well?


Dewey's attitude towards epistemology


            According to Richard Rorty (whose views are in danger of becoming the orthodox modern interpretation of Pragmatism[2]) the pragmatists at their best scorned epistemology, and except during  confused moments of weakness like Dewey's "Experience and Nature", believed it should be completely ignored . This interpretation  was probably inspired by statements like this from Dewey.


. . . .intellectual progress usually occurs through sheer abandonment of questions together with both of the alternatives they assume--an abandonment that results from their decreasing vitality and a change of urgent interest. We do not solve them: we get over them. Old questions are solved by disappearing, evaporating, while new questions corresponding to the changed attitude of endeavor and preference take their place. (Dewey 1910, p. 19)


            I think, however,  that  Rorty goes further than Dewey intended when he talks about disposing of epistemology by simply "changing  the subject." For eliminating questions about a subject is not the same as ignoring the subject altogether.  Astronomy did not close up shop when it stopped asking the question "what turns the crystal spheres?", and the fact that Dewey wants to abandon the traditional epistemological questions does not mean he wants to abandon epistemology. He does want to abandon epistemology's  traditional aspiration to be the most fundamental human discipline. For he does not consider human beings to be fundamentally creatures that know, nor does he assume that all other human activities can be understood by studying how we think. Epistemology thus loses the position that Kant claimed for it i.e. of being the foundation for all other disciplines. But the claim that the subject of epistemology is not as fundamental as was once thought does not imply that the subject itself disappears.


            For Dewey to study knowledge is to study inquiry, and inquiry is only one of many human activities. It is a very important activity, perhaps the activity that is most uniquely human. But knowing how to conduct inquiry is only one kind of "knowing-how", that is, only one way that people relate to their experience, and to each other in society.  Dewey's concept of experience is thus radically different from the British Empiricists, who saw the flux of our daily experience to be a series of confrontations with a succession of simple ideas, each confrontation resulting in a kind of knowledge. For the British Empiricists, to be conscious was to be aware, and to be aware was to possesses knowledge of what you are aware of.  Dewey rejected this,  claiming instead that we have experience prior to knowledge. Experience is what knowledge starts from, and is its ultimate arbiter. If our theories cannot make sense out of our experience, they must be changed. But experience itself is not knowledge; we get knowledge only after inquiring into our experience.


            This hasty description of the relationship between knowledge and experience still presupposes many  ideas that Dewey wants to reject.  Deweyan epistemology wants to shift from studying knowledge, which seems to be a static "thing" that we acquire, to studying inquiry, which is an activity.   For Dewey, "knowledge" was rather like a nominalization of a verb, rather than a genuine noun, and he was vigilant in exposing the confusions that resulted from ignoring this. Much of his "Democracy and Education" is devoted to exploring the damage done by the assumption that knowledge is a commodity, and that the goal of education is to cram as much of that commodity as possible into a person's memory. ( A view of education that is still presupposed by many practitioners of computational "GOFAI" artificial intelligence, who assume that the way to create a more knowledgeable machine is to fill it with the right sort of information, and teach it how to access that information correctly.)  When Dewey maps out his five steps in the process of inquiry, it is clear that for him inquiry is a specialized activity that is performed only at certain times, i.e. when things don't work. When things do work, and we feel at home in the world, we do not engage in inquiry. Consequently, no epistemological categories can fully explain our experience, and especially not categories which assume that experience is a commodity consisting of independent moments that directly present themselves to us. 


            Suppose that there were strong evidence from Neuroscience that human beings are not fundamentally organisms that know? That experience was fundamentally constituted not by an awareness (a knowing-that) of independent facts  but rather by a kind of skillful coping (a knowing-how) that could operate independently of verbalizable knowledge? Surely such scientific evidence would strengthen and clarify Dewey's theory of experience. Dewey believed that "experience is in truth a matter of activities, instinctive and impulsive in their interactions with things . . .  the neglect of the deep seated active and motor factors of experience is a fatal defect of the traditional empirical philosophy"(Dewey 1923 p.281.) If modern neurological evidence indicates that knowing-how and the motor factors of experience are more fundamental than knowing-that, and could operate independently from linguistic knowledge, wouldn't the biological structures that made such skillful coping possible be a good candidate for the embodiment of those non-cognitive aspects of mental life that Dewey calls experience? I think so, which is why I am now going to lead my readers  into the thickets of connectionist cognitive science.


Connectionist Function and Structure


            I believe that the neurally inspired structures of connectionist architecture are the best functional descriptions we have of what Sellars called sensa or sensations, and Dewey called Experience. These architectures are based on neuroscientific and Artificial Intelligence (AI) research that Sellars would probably not have had access to, and Dewey could not possibly have had access to. But they make it possible to talk about sensations and experience as something distinct from linguistic thought, without having to rely on mystical concepts like immediate givenness or direct apprehension. Before I can demonstrate this, however, I'm going to have to describe some of the ways that a connectionist net creates organized behavior. This story has been retold many times in the books and journals of the cognitive philosophy community. (P.M. Churchland 1989, 1995; P.S. Churchland 1992; Clark 1993; Bechtel and Abrahamsen 1991; Bickle 1998; Haugeland 1997 and on and on.) No one who tells this story emphasizes exactly the same points, for the full philosophical implications of these discoveries are still being explored. My version of the story will, of course, help to grind my particular philosophical ax, and will therefore ignore many other  points of philosophical and scientific interest. Those who find my version too lacking in detail are encouraged to read any and all of the other sources cited above.


            I am going to try to describe connectionist nets in purely functional terms. I will, in other words, provide a relatively brief abstract description that makes almost no reference to the "wet" neurology, and very little reference to the computational math, that makes connectionist learning possible. There will consequently be very little about physically how connectionist nets work; the emphasis will be on what it is they do. This will hopefully enable me to avoid boring those who have already read the neuroscience and the AI, and avoid confusing those who have not. But more importantly,  it will bring into sharp focus those characteristics of connectionist nets that are important for the philosophical points I am trying to make. Specifically, I'm going to emphasize how neural nets are able to perform certain important cognitive functions without using anything that can be called language or logical inference. This will help show why, if knowledge/thought is fundamentally linguistic, we can then literally give flesh to the other side of both Dewey's distinction between knowledge and experience and  Sellars' distinction between thought and sensation.


            A connectionist net is capable of the following two behaviors which are of interest to us.

            1) It can transform one set of numerical vectors into another set, in ways that make possible appropriate responses to an environment
. The simplest starting point  for explaining connectionist vector transformations  is neither connectionist nor a vector. Consider a thermostat, which responds to a single numerically measurable value (the temperature of a room) and uses that information to change some other numerically measurable value, thus controlling a device that either increases or decreases the heat output of a furnace. (figure 1). A connectionist net is able to take not just one such input, but a large array of numerical inputs ( a vector), and transform that vector into another vector which can in turn perform some function in a biological system. (in much the same way that  the output of the thermostat performs a function in a heating system). The function is far more sophisticated, however, because the connectionist net is able to take a particular group of input vectors and respond to them with a single output vector, thus creating a one-many relationship that functions in ways similar to the universal-particular relationship in conceptual thinking. (figure 2) It can, for example, learn to recognize the vector produced by light rays bouncing off several different type faces of the letter "A" and onto an array of light sensitive inputs. By "recognize", I mean that it will produce the same output vector each time it encounters the many different input vectors that are all caused by different type faces of the letter "A". In fact, a single connectionist net can learn to make a variety of different responses that can be used to classify a manifold of inputs into categories. It can, for example, learn to identify many different "A"s as all being "A"s,  "B"s as "B"s, etc. for all 26 letters of the alphabet.



            2) It can respond to new situations in ways that can be described as 'learning".


            Connectionist nets are touted as "the machines that learn", and this usually refers to two very similar virtues.


            Firstly, there is a complicated process by which one adjusts the weights between the connections of the nodes in the net. This process is called "training the net", because it results in a net that makes fewer errors. However, many people claim we have no reason to assume that this training process significantly resembles the way our own neural networks are trained, and those who claim otherwise admit that there is still no proof for any of the best possibilities( see Stork 1989). Consequently, although this training process is a very helpful piece of technology, we cannot accurately extrapolate from it to our own case. Strictly speaking, artificial connectionist nets do not teach themselves during this process, they are shaped and taught by a very unconnectionist algorithm.


            There is, however, another quality that nets have which is very much like learning and very much intrinsic to them. During the training process, a net is exposed to a relatively small number of training examples, and on the basis of those it is able to make judgments about many examples it has not yet seen. If you train a letter recognition net to respond correctly to several examples of the letter "A", it will also be able to correctly identify numerous other type faces of the same letter it has never seen before, without any further training.


            Here is a simplified explanation for this apparently amazing fact. Think of a single neuronal node in a net as representing a dimension in a Cartesian coordinate space, and think of the nodes' possible inputs or outputs as describing points along that dimension. If we have ten possible values that are significant to the network for each node, then 3 nodes could describe a thousand different points (103) in what is called computational space. Figure. 3 is a picture of a very simple computational space of this sort, which is divided up into two distinct regions.  Every possible signal the net can receive is a point in this computational space. What this particular  connectionist net learned to do was respond to any signals it received with one of two possible outputs, depending upon which of these two regions contains the point described by value of the signal. A net trained to recognize the letters of the alphabet would have to make twenty six different responses, and thus the computational space would be divided into twenty-six regions. During the training process, the net is exposed to members of the categories it is learning to recognize, and then the boundary lines of these computational regions are readjusted so that the net gives the correct response in each case.  And once this training process has been completed,  the net will respond correctly to other members of the same category, because the signals they produce are within the borders of the newly adjusted computational spaces.


            Thus, a network trained to recognize the letter "A" will see a new type face that was not part of its original training set, but the net will recognize it because its input vector describes a point within the boundaries marked off during the training process. Because there could be literally billions of points within a region that was outlined by relatively few training examples, a properly trained network can make accurate judgments about many things it has never seen before. Thus once our letter-recognition device has been trained to recognize the letter "A" in Palatino, Geneva, and Zapf Chancery, it will automatically correctly classify  "A"s  in Helvetica, Times, and Courier, because the input produced by "A"s  in those fonts occupies the same region of computational space as the training set, as do "A"s in hundreds of other typefaces the system has not yet seen (or may never see, as well as possible typefaces that may never exist.) This ability to extrapolate from a training set is greatly increased as the amount of computational space increases. To understand just how much computational power  a biological brain possesses,  ponder instead of a cube, a region of space that has a million dimensions. (you won't be able to actually imagine this unless your mind is very different from mine.) This region would have 101,000,000 points (i.e. 10 to the millionth power) that could be carved up in almost any conceivable way[3], and each region could be associated with an appropriate response by means of a training process. And once this association has been established, the net would be able to make the association correctly for billions of points it has never encountered before, because those points are also within the borders of the demarcated space. Because the human brain has something like 1012 neurons, it could in principle learn to make distinctions that divide up 10 to the 1012 points, (which is much more than a trillion trillion times as many points as there are elementary particles in the universe) into many different spaces of many different shapes.


            Given the vast amount of resources that our nervous system has to work with, it seems highly plausible that it could use the same basic architecture to establish a similar relationship between A) the computational space described by the input received from our retinas and B) an appropriate linguistic response, such as "there is a pink ice cube in front of me".  Each region of computational space could be seen as a sense datum, and the fact that the computational space is so vast seems to explain how we are able to store so many of them. One region of computational space could contain the sense data, and the other could contain a list of sentences like "there is a pink ice cube", "there is a red apple", and so on, and learning would consist of correlating the right retinal input with the right sentences


            This description between the relationship between language and experience might satisfy Sellars, at least under certain interpretations. But it would not have satisfied Dewey.  He saw experience not as discrete moments correlatable with observation sentences, but rather divided into activities that blurred into each other, and took amounts of time varying from seconds to hours. And more importantly, he saw experiences not as detached observations of a world, but rather constituted  by the emotions, goals and desires of the experiencer.  The Deweyan view is a much more accurate view of experience as understood by modern neuroscience, although sometimes certain AI experiments make it difficult to see this. To some degree,  the AI experiments described above are shaped by the presuppositions of logical positivism, and research has a tendency to find what it is looking for.  For one thing, these experiments  superimpose the law of the excluded middle on top of a system that doesn't really support it. The outputs of the net are not actually identical for every single response that the experimenters label as identical.  In an alphabet recognition program,  a certain range  of responses is labeled as the "A" response, another range of responses is considered to be the "B" response and so on. When the experimenters are training the net, they are only trying to get every single "A" to produce a response within the "A" range. For the purposes of the experimental protocol, these responses can be interpreted as one of twenty six different and discrete responses, which can be correlated with observations sentences like "That's an A", That's a B" etc.. And this is an essential interpretation if we start with the assumption that a knowledgable person is one who can emit the correct sentence when in the presence of the object that the sentence refers to. The fact that no two responses are exactly alike can be dismissed as harmless noise that doesn't really detract from the signal.


             When a neural net is in an actual biological brain, however, the perceptual inputs it receives are rarely used for the purpose of generating observation sentences. In fact they are never used for that purpose in animals, for obvious reasons. Instead they are used to control complicated pieces of skillful motor movements--tracking prey with the eyes as it runs through tall grass, monitoring the sound of a violin to  make sure that it stays in tune, or stripping leaves off of branches in such a way as to make sure that the edible parts come off in your prehensile paws or trunk. In order to control a process as complicated as any of these, the neural net needs to set up a relationship with more than just a single output vector that can be assigned a single linguistic value.  It needs to have a relationship with another whole region of multidimensional computational space, and that relationship needs to vary depending on the variations in the stimulus. Thus the analog nature of the net's responses, which is deliberately ignored when pattern recognition means making a particular linguistic response, becomes essential to the functioning of those nets which are designed to control "knowing-how" abilities like the examples listed above. We would thus need to redescribe the basic architectural principle of  connectionist nets to capture their ability to embody know-how.


                        Instead of correlating a cube with a set of observation sentences, we would need to think of two cubes A and B, each like the one in figure 3, except that each cube is divided into, say,  26 different regions instead of only 2. (figure 4) No two regions in either cube are the same shape or cover exactly the same territory. Now (in order to help you visualize the computational relations between the two cubes)  mentally color one region in each cube red, another pair of regions in each cube blue, and so on for all 26 different regions. What a connectionist net does is establish relationships between ordered pairs of computational spaces, so that whenever the net receives input that describes a set of points within the red region of cube A, it outputs a set of points within the red region of cube B, and so on for all 26 colors shared  by each cube.  Imagine, for example, that cube A contains all the different points that describe a perceptual input, such as all the different angles and speeds of an oncoming fast ball, and cube B contains all of the different ways that one could stand, hold the bat, times ones' swing etc.  If the relationship between the two cubes is tuned properly, the muscles' movement will change as the perceptual inputs change, and the result will be a home run  for most of the different ways that the ball could travel over the plate. And in principle the same kind of relationship could be established between an organism and its environment for a variety of other skills: painting a picture, closing a business deal, comforting a child.


            Of course skills of this level of complexity could not be modeled by only two connected computational spaces. To get a sense of the architecture for these more sophisticated skills,  we would have to imagine even more multidimensional spaces that are linked together in a variety of complex ways , including links that feed back to previous links. (Figure 5). There is far more to be learned about such architecture, but what we know already gives strong evidence for a point that is important for our purposes. In such a system, each layer of nodes could "make a decision" about which vector within its space to output to the next layer, based on what input it received from the previous layer. But this "decision" would not be a logical inference, nor could anything in it be legitimately called a word or a sentence. The nearest thing to verbal translation of the behavior of a trained connectionist net would be the single sentence "When you get input that resembles this, do something that resembles that."  repeated and strung together by conjunctions. But this description would be completely empty, and equally applicable to every connectionist net. The "content" of the connectionist net, the information that gives it it's cognitive power, is determined by how the computational space is divided up, and this is expressible only in geometry, not in any language made up of sentences.


            Although there has been some controversy over whether the regions of computational space in a net are describable as representations, no one would claim that their interactions were fundamentally describable as a language.  Even those who believe that a Language of Thought theory is the best description of higher cognitive processes acknowledge that connectionism successfully implements "lower" processes like perception and motor control. And this means that no Language of Thought theorist denies that there are many activities that are describable as cognitive in some sense which is clearly not linguistic. The controversy between Language of Thought theorists and Connectionists is over whether connectionism can eventually reduce or eliminate a Language of Thought. No one is claiming that things could go the other way around, and we could eventually describe Connectionist nets with a Language of Thought theory.


            When you recall that each of these "cubes" is actually an unimaginably vast multi-dimensional computational space, and that each of these spaces can respond to a variety of different inputs in a variety of specific ways, it seems plausible that  such a system would be capable of very sophisticated behaviors.  And it has already been shown from successful experiments in Artificial Intelligence laboratories, that this kind of architecture can model a variety of sophisticated "knowing-how" abilities. These abilities have also become one of the main focuses of Cognitive Neuroscience. P.S. Churchland's and  T. Sejnowski's "the Computational Brain" deals almost entirely with research on modeling  motor control abilities. Traditionally motor control has not been thought of as a cognitive activity. The assumption was that  when we moved our bodies, our brains were merely sending signals to trigger preset patterns that ran like clockwork. (see Dreyfus 1972 pp. 235-6 for Descartes' views on this. ) But the recent research in cognitive neuroscience research reveals that  the connectionist systems that control our muscular skills (or even the skills possessed by simple creatures like leeches and cockroaches) require far more flexibility and responsiveness than is possessed by the preset algorithms that govern the behavior of mechanical toys. This is why mechanical toys fall over much more frequently than we do; because they do not receive feedback from the environment.  People have tried to build robots which received feedback that was translated into some kind of language read by a centralized processor, and then translated  into motor commands. But the feedback produced responses that were so slow as to be almost useless. (see Clark 1997) Connectionist nets have a flexibility lacking in language based systems because 1) vector transformations can translate perceptual input directly into motor control, without  an intermediate linguistic process  2) Connectionist nets can give the right motor response even if the perceptual input they are receiving is not identical to the inputs they were trained on. The only thing they need is for the input to be appropriately similar, in a sense of similarity that is geometrically, (not verbally), described by a region of computational space.


Knowing-How and Neural Nets


            To sum up: Connectionist nets  perform vector transformations which interrelate different regions of computational space.  This basic principle has been effectively used to model both perception and motor control, and research in cognitive neuroscience has revealed that it is often misleading to distinguish the two. In most cases, what a neural net does in real biological life is use perception to directly guide motor control. And this guidance is accomplished by means of processes which are not at all linguistic, which means that they make possible a kind of knowing-how that does not rely on any sort of knowing-that. It thus seems that the following quote from Sellars states a once widely held philosophical position that  has been pretty much disproven by what we have learned about connectionism.


     It can be argued that anything which can be properly called "knowing how to do something" presupposes a body of knowledge that; or to put it differently knowledge of truth or facts. If this were so, then the statement that "ducks know how  to swim" would be as metaphorical as the statement that they know that  water supports them (Sellars 1963 p.1)



            We can see from the "if" that begins the second sentence that Sellars was clearly ambivalent about this claim himself. But it is obvious from his wording that he believed many of his readers in 1963 would have taken it very seriously. But now there are many people in Cognitive Science who believe that the facts cannot possibly support such a claim. (See Dreyfus and Dreyfus 1986, Dreyfus 1996,  Clark 1993, and Hilditch 1995). I count myself among their number, and I think that anyone who is truly familiar with connectionist nets would agree with me. There is nothing going on in a connectionist net that remotely resembles logical inferences from  propositions that state facts. And yet connectionist nets are very successful at modeling both motor skills and perceptual judgments, which are obviously the main components of the most prototypical kinds of "knowing how". Indeed, a duck's knowing how to swim must consist entirely of motor skills and perceptual judgments. We already know enough about Cognitive neuroscience to be almost certain that this is true of cockroaches (See Churchland and Sejnowski 1992, as well as the numerous citations within it.)  More importantly, Connectionist nets are far more successful than were the attempts at modeling perception and motor control with the logical and sentential paradigms of symbolic systems AI. ( See Dreyfus 1994.)


            Although knowledge of the right truths or facts clearly provides aid and comfort to the developing of "knowing-how" abilities of humans, awareness of these facts usually doesn't come into play when the abilities are in use. Teachers of knowing-how abilities (such as athletic coaches, and arts instructors) have usually dealt with this fact by either 1) saying that the knowledge of the facts drops out of consciousness, but continues to function subconsciously in a basically linguistic manner or 2) relying on mystic exhortations along the lines of "cultivate the mind of no-mindedness" or "use the force!". Neither of these alternatives is necessary when we can see linguistic abilities as distinct from perceptual and motor abilities, because the former uses logic and sentences and the latter relies on vector transformations. A (rather ugly) connectionist translation of "cultivate the mind of no-mindedness" would be "don't let your linguistic mental processes get in the way of your vector-transformation processes."


            To understand the fundamentally non-linguistic nature of vector transformations, consider our old friend the thermostat. There is a real and meaningful  sense in which a digital computer can be said to talk to other computers, or to itself, when it manipulates bits of information in accordance with logical principles. However, no one but a poet (or a Disney cartoonist) would be tempted to say that a thermostat is talking to the furnace when it translates the temperature of a room into the exact voltage necessary to lower the fuel input into the furnace and thus eventually restore the desired temperature. (Although some would describe this function as representational. See Bechtel 1998) The connectionist systems that govern motor control operate under the same basic principle as the thermostat, only they take many different arrays of perceptual inputs and translate them into many different arrays of motor control outputs.  And because each layer in the system marks off vast regions of computational space, each of which describes a range of possible appropriate responses, it can respond with a level of flexibility (described by  Hilditch and Merleau-Ponty as "improvisational"[4]) which is far beyond the capabilities of a non-connectionist translation device like the thermostat.


            Both Dewey and Sellars prophecy this distinction between the linguistic and the non-linguistic with distinctions of their own. Dewey was far more in tune with this modern formulation, for he saw what he called "experience" as consisting of perception, motor control, and purposive strivings united in a single organic whole. Sellars, as we shall see in the next few paragraphs, originally saw his concept of "sensation" as a component only of perception. To some degree, he started out assuming that he would only need to make a few reformations of classical sense datum theory, but his reforms eventually became every bit as revolutionary as Dewey's.


Sellars and Connectionism


            In "the Structure of Knowledge", Sellars starts with the sense datum theorist's paradigm of knowledge: The single experience of deliberately looking at an object in front of us. He then claims this apparently unified experience consists of two distinct process, and (as he often said in class) the only reason that these processes occur simultaneously is that people can chew gum and walk at the same time. The first process is completely cognitive, and consists of the occurrence of a sentence in the mind, saying something like "lo, a pink ice cube over there". The second process is completely non-cognitive, and consists of a manner of sensing. At the time one would be thinking the previously mentioned sentence, there would also be an occurrence in the mind of a  process Sellars called "sensing a-pink-cube-ly". From what we now know about connectionism, it is clear that Sellars was largely right about this distinction, because the processes of vector transformations that create sensory experience are fundamentally non-linguistic, and for philosophers of Sellars' generation all cognition was linguistic. Even though Sellars frequently expressed misgivings about this assumption, he never really felt that he had the resources to offer any alternative.


            In spite of this lack of resources, however, he comes extremely close to making a distinction between two distinct kinds of knowledge which is coextensive with the language/vector transformation distinction, even though it could not possibly contain any of the computational details. In "the Structure of Knowledge" Sellars introduces his distinction between thought and sensing by saying that musicians and composers have two different ways of thinking about their art. They can think about sound (i.e. linguistically) and they can also non-linguistically think in sound. He then makes the following conclusion from this, which seems to contradict many of his other statements.


       There is much food for thought in these reflections. . . But the fundamental problems which they pose arise already at the perceptual level. For as we shall see, visual perception, itself is not just a conceptualizing of colored objects within the visual range-a 'thinking about' colored objects in a certain context--but in a sense most difficult to analyze, a thinking in color  about colored objects (Chastened Ed. 1975 p.305)


Sellars was certainly right that this sense was most difficult to analyze. How can the above be reconciled with this claim?


      all awareness of sorts, resemblances, facts, etc., in short all awareness of abstract entities -- indeed, all awareness of even particulars -- is a linguistic affair  (Sellars 1963).


             Is there anything left to be aware of that isn't on the above quoted list? And what do we do with his repeated claims that sensations are non-cognitive? The first paragraph of Sellars 1981 actually seem to be implying that sensations are also different from non-linguistic thought. This seems to leave us with three categories of mental events, exemplified by 1) linguistic thoughts about sound 2) non-linguistic thinkings in sound, and 3) Audial sensations. There is no question that Sellars worked very hard at this question, and I won't claim that there isn't an argument buried in his writings somewhere that exonerates him of logical inconsistency on this point. But now that we have the conceptual resources of connectionism to explain what happens during "Thinking-in-sound" or "Thinking-in-shape-and-color", I think it makes sense to cut this particular Gordian knot rather than continue to try to untie it. The most plausible exegesis is that Sellars was right when he said that sensing is non-linguistic, and wrong when he said it is non-cognitive. This is perfectly understandable mistake, given that linguistic cognition was the only kind he knew about. For Sellars, (and his opponents) there were only two alternatives: Awareness was either linguistic or direct apprehension of something immediately given, and he knew better than anyone that the latter alternative was unacceptable.


            There is also something very right about Sellar's insistence that the sensing part of the perception was non-inferential, and it became the basis of one his most important critiques of sense datum theory. It really is impossible to make an inference from a particular "sensing a-pink-cube-ly", even though it is fully justifiable to make an inference from the  mental sentence that accompanies it. To think otherwise (as did the sense datum theorists) is to make a category mistake along the lines of trying to make an inference from a walnut. (as opposed to making inferences from a sentence about a walnut.) This is why Sellars describes our sensations as being "non-inferential." However, the fact that you cannot make logical inferences from a sensation does not mean that it is not cognitive in the broad sense that connectionist cognitive science defines "cognitive". For if a sensation is the product of a series of appropriate vector transformations it might enable us to move skillfully through the world even if it was not accompanied by any sentences that would enable us to talk to ourselves about it. It might, for example, help me in reaching skillfully across the room to pick up the pink ice cube and put it in my drink, even though I was completely absorbed in the discussion of some other topic.



Sense Data vs. Sensory Process


             If sensing and thinking can be divided this way--if they are as distinct as chewing gum and walking-- wouldn't there be many occasions when we would chew gum and not walk, or vice versa?  Although Sellars acknowledges this in principle he almost always used the same paradigm explanandum as the sense datum theorists: a single moment of perception, in which one focuses on an object in one's perceptual field and makes a judgment about it. He did not slice perceptions as finely as did the classical sense datum theorists, who saw the fundamental parts of perceptions to be rather like frames of film that contained weird artifacts like elliptical pennies. But the examples he usually used required him to share the sense datum theorist's  presumption that the world is always encountered as what Heidegger called being-present-at-hand. I sit in my chair, the pink ice cube sits on my table, and I look at the pink ice cube in an attempt to understand it, or acquire some information about it. The sentence that comes to me at the moment of perceptual taking lasts a second or two, and there is a sensation of color-and-shape going on during the whole time I am thinking that sentence. From this, it seems tempting to infer that Sellars sees our sensations as divided up  into chunks of a second or two,  each of which matches one of those mentalese speech acts that he calls a perceptual taking. Consider, for example, this passsage from Sellars 1963, which offers an explanation for how linguistic knowledge can be derived from pre-linguistic experience.


  While Jones's ability to give inductive reasons today  is built on a long history of acquiring and manifesting verbal habits in perceptual situations, and, in particular, the occurrence of verbal episodes, e.g. "This is green," which is superficially like those which are later properly said to express observational knowledge, it does not require that any episode in this prior time {i.e. before Jones had language} be characterizeable as expressing knowledge.


. . . {Footnote added in 1963} My thought was that one can have direct (non-inferential) knowledge of a past fact which one did not or even (as in the case envisaged) could not conceptualize at the time it was present.  (Sellars 1963 p.169)[5]



            I first interpreted this passage to mean that if a baby looked into a refrigerator before she ever could say to herself "that is a Pink Ice Cube", the experience produced in her would still be divided up into cubes of pink, tray-shaped chunks of tray-color, and "Mrs. Paul's frozen fish sticks"- shaped chunks of "Mrs. Paul's frozen fish sticks"-color. If my interpretation had been correct, Sellars would have been a reformer of sense datum theory, rather than a revolutionary working against it. To paraphrase his words for my purposes, he would be teetering on the brink of sense datum theory, and claiming that he has not fallen over the edge. And as one can no doubt tell from the sarcastic tone of my examples, I would not have been sympathetic to this view.


            But many years later, with the appearance of his three Carus lectures, he ends up not only stepping back from the brink, but running so far away from it that almost no one in the analytic tradition is willing to follow him. And as Jay Rosenberg 1982 points out, there are many indications (including the quote from Sellars 1963b that closes the Carus lectures) that Sellars believed something like these revolutionary claims even when he described himself as basically a reformer of sense datum theory. To sum up the Carus lectures in the most flamboyant way possible: Our sensory experience is a pure absolute process. It ebbs and flows as "an on-going tissue of goings-on" with moments that can be conveniently given labels like "sensing a-pink-cube-ly". Fundamentally, however, there are no objects at all. Even the objects of science should seen as examples of the pure process "quarking" and "electroning". This, Sellars claims is the only way we can account for the fact that there are occurrent properties like shape and color sharing the universe with theoretical entities like quarks and electrons.

            This view resembles both Dewey and James in many interesting ways, and Sellars' arguments for it make it far more convincing than it appears to be in this blunt statement. But from this God's eye view of the Ultimate Nature of Things, it's rather difficult to consider the issues of epistemology and philosophy of mind that are the main focus of this paper. And more importantly, the unwillingness to accept anything less than such a God's eye view is the crucial difference between Sellars' Scientific Realism and Dewey's Pragmatic Pluralism. Before Sellars puts forth his theory of absolute process, he describes four other alternatives, all of which he claims are unacceptable. Two of them, one of which he calls instrumentalism , and the other emergentism,  pretty much cover Dewey's  metaphysical position. The following passage from EPM nicely sums up Sellars' differences and similarities with Dewey on this issue.


     As long as the existing framework {i.e. of the common-sense Manifest Image} is used, it will be incorrect  to say -- otherwise than to make a philosophical point about the framework -- that no object is really colored, or is located in Space, or endures through Time. But, speaking as a philosopher, I am quite prepared to say that the common-sense world of physical objects in Space and Time is unreal -- that is, that there are no such things. Or, to put it less paradoxically, that in the dimension of describing and explaining the world, science is the measure of all things, of what is that it is, and of what is not that it is not. (Sellars 1963a p. 173 italics in original)


            There are certain hints of something like pragmatic pluralism in the first sentence quoted above[6], as there are in Sellars' definition of success in philosophy as knowing ones way around with respect to all things (Sellars 1963b  p.1) But the rest of the quote makes it clear that for Sellars, science is strictly speaking the measure of all things. Dewey  rejected the idea that any one system of thought could be the measure of all things. He believed that there were a variety of ways to measure and comprehend things,  and the question of which was the best was answerable only if you qualified it by answering the further question "best for what?".  Consequently I don't think Dewey would claim that Sellars is mistaken in claiming that  the universe is an absolute process, only in claiming that this absolute process was realer than the various relative processes that make up the daily flux of our experience. If your goal is to resolve certain philosophical problems, Sellars' absolute process theory may be arguably best for that purpose. But according to Dewey, that does not make it the measure of all things, it just makes it a very good theory for philosophical purposes. A scientific realist like Sellars would probably consider such a view to be instrumentalist, although it does not entail many of the instrumentalist assumptions that are associated with  instrumentalists in the analytic tradition like Bas Van Fraassen and the operationalist Carnap. (Sellars outlines some of these assumptions on pp. 43 and 44 of his 1963b.) And because Dewey believes that there is no one answer to the question "what is truth?", the whole problem of emergence doesn't even come up. Emergence is only a mystery if you think that the universe must be constituted by a single unified system. If so, when something emerges that has no obvious relationship to that system, this is a fact that calls for an explanation. But there is no puzzle of figuring out how the world ties together into a single system if the world is not in fact tied together into a single system. [7]


            Consequently, for Dewey the key issue is not the  relationship between  some kind of pure process and knowledge. It is the relationship between experience (which is constituted by processes that are directed by our goals and emotions) and inquiry (which is a way of transforming those process in such a way as to enable us to better know our way around the world in which we live.) And as with Sellars, I think that a consideration of the connectionist nature of our minds will clarify much of what previously appeared to be mysterious in Dewey's theory of experience.


Connectionism and Dewey's concept of Experience


             In his 1994 article, Shusterman criticizes  Dewey's concept of experience as a kind of unacknowledged foundationalism, because he claims Dewey sees immediate quality as "the underlying guide of all thought and discourse" (p.134). Shusterman claims that Dewey asserts this about all thinking, discourse and judgment, and that this amounts to "a foundational metaphysics of presence justified by transcendental argument" (ibid.) He suggests that Dewey can remain truer to his own spirit if he acknowledges that  "given the structuring of habit and purpose, there is no need to appeal to a special unifying quality, a felt presence, to organize the situations as an organized whole."(ibid.)  Shusterman claims that anything that can be clarified by discussing qualitative thought or experience can be dealt with more effectively by considering how our behavior is conditioned by our habits and purposes, without leaving us open to the dangers of foundationalism and/or ineffablity. He does not feel that Deweyan philosophers should ignore immediate experience. But he feels that it would be more in line with Dewey's principles to use philosophy to "establish and improve the quality of immediate experience as a practical and useful tool." (p.136), rather than using it as a theoretical foundation in epistemology.


            My debt to Shusterman in this paper is enormous, and it is one of the pathologies of the philosophical profession that I can only acknowledge this debt by criticizing his article.  The reader should remember that I am taking the trouble to show where I think he is wrong because no one else has gotten so much else right. I could quarrel with his conflation of benign concepts like "guide" with pernicious ones like "foundation". But I think most of my disagreements with him spring from the fact that he assumes no one in the contemporary philosophical community would question Pierce's claim that "my language is the sum total of myself". To some degree he is right, but this consensus rests on the assumption that Quine and Sellars have proven this point, and as I tried to show earlier in this paper, this is not all that obvious. Shusterman quotes Sellars as saying "All awareness is a linguistic affair" but makes no reference to any of Sellars' equivocations on the issue of sensations and "thinkings-in-color". In fact, while Dewey may be out of step with Sellarsians like Rorty, his position on experience is very similar to that of Sellars himself.


     . . . .to be a smell is one thing, to be known as a smell, another; to be a "feeling" one thing, to be known as a "feeling" another (Dewey 1910 p.81)


            If we substitute  "a-pink-cube"ly manners of sensing for smells and feelings, this claim is identical with the Sellarsian distinction between thoughts and sensations we discussed earlier. This means that connectionist theory should be as helpful in clarifying Dewey's theory of experience as it was for Sellars' theory of sensation.  I maintain that talk about sensations and/or qualitative experience appears to refer to some kind of mystical ineffability only when the sole model we have for mental life is a linguistic one.  If the smells and the "feelings"  are constituted by vector transformations of the sort described previously, and the thoughts (which make knowledge possible) are constituted by inner linguistic events, the ineffability is no longer mysterious. What we have instead are two completely biological processes taking place in living organisms. But because one of the processes is linguistic and the other is not, the latter cannot be reduced to the former. Dewey's unique contribution was to show the advantages of assuming that they were different processes. Unfortunately, because he could not explain the two different mechanisms that distinguished knowing from feeling, it sounded like he was being mystical when he claimed they must be separate.


            Until very recently, it was usually assumed that both sensations and thoughts, knowings-how and knowings-that, were constituted by processes that were essentially the same and essentially linguistic and propositional. (As Sellars was fond of pointing out, the classical empiricist mistake was to assume that sense data granted an awareness of facts, from which logical inferences could be made.) Jerry Fodor ridiculed this idea by saying that when we tie our shoes, there is a little man in our heads who gets a book down from a shelf titled "how to tie your shoes" and then follows the instructions in the book. (Fodor 1981) But as is his wont, after ridiculing this idea, Fodor then claims that it is the only real explanation we have, and that it is fundamentally sound. According to this theory, the difference between those processes that we use in skillful coping and those that we use in verbal deliberations is nothing more than the fact that the latter are under the spotlight of awareness and the former are not.


            Dewey wanted to claim that experience is not just vaguely perceived knowledge, but something different in kind from knowledge; something constituted by our habits, skills, and abilities, and necessarily linked to our goals, aspirations, and emotions. Throughout it's history, philosophy has concentrated on understanding the architecture that made rational thought possible: i.e. language. Language is the thing which separate us from the brutes, and entitles us to the Aristotelian honorific "Rational Animal". For that reason, most philosophers associated conceptual thought with the abstract and the spiritual, and it was thus considered to be the thing that made us conscious beings. Felt experiences were considered to be thoughts that were deficient in some way: They were confused thoughts, waiting to be brought into focus, or atomistic bits of thought waiting to be assembled into scientific theory. Dewey's radical claim was that experience was not only distinct from thought, but also had rules of organization that were all it's own.


            I've devoted quite a bit of space in this paper to explaining some of the capabilities of connectionist nets, in hopes of demonstrating how they can justify two closely related distinctions in Dewey and Sellars. There are also some other developments in experimental psychology which provide even more empirical justification for Dewey, and relate significantly to connectionism as well. When experimental psychology began to encounter the inadequacies of traditional sense datum theory, psychologists like J.J. Gibson and Ulrich Nesser began to talk about considering the senses to be organized into perceptual systems. (Gibson 1950, 1966. Nesser 1992, 1994). Gibson, in particular, made some very perceptive observations about certain organizing principles that govern the perceptual field, which were a welcome relief from the traditional view that sensory experience consisted of independent directly given particles.  Gibson's The Senses Considered as Perceptual Systems seems to imply that these perceptual systems present themselves to consciousness in essentially the same way that the sense data were once assumed to do. It appeared that the only difference was that the perceptual systems presented themselves all at once rather than in little bits, or perhaps that they provided a form that conditioned the raw content of sensations.  However, there is no such implication in Gibson's later work, such as the Ecological approach to Visual Perception, which describes a space not filled with neutral objects, but divided up into what he calls affordances. In an essay of his quoted in Hilditch 1995 (p.42), Gibson describes the space we experience while driving an automobile. What we experience is not shapes and colors, or even objects, but specific opportunities for driving action: the field of safe travel, the minimum stopping zone, the distance required to reach from the brake to the clutch. Each of these fields is called an affordance, because it affords an opportunity for a specific kind of action.


            Although he uses the term "direct perception" to describe the relationship between organism and affordance, Gibson means almost exactly the opposite of what the sense datum tradition meant by that term. For Gibson, the perception of an affordance is direct because it does not make a stop in the cognitive center of the brain long enough for us to construct a sentence about it. Instead it goes directly from the retina into muscular control centers, bypassing the kind of conceptual categorization that makes thought and reasoning possible. Although Gibson did most of his work before connectionist theory was developed, he did a thorough job of observing the sort of functions that connectionism is good at implementing. The network of affordances that defines our relationship to our world is  constituted by opportunities to utilize "knowing-how" skills and abilities.  And Gibson was able to see that such a network functioned without reference to linguistic thought, even before connectionist theory existed to explain exactly how that was possible.


            Gibson's claim that our primary experience is a world of affordances is extremely similar to Dewey's. Gibson's claim that our awareness of affordances is direct, and distinct from the kind of knowledge that makes categorization possible, seems to imply that we can map his distinction between direct and categorizing perception onto Dewey's distinction between knowledge and experience.[8] The only apparent problem with this mapping is that Dewey considered experience to contain not just skills and abilities, but also goals and emotions. I think, however, that extending Gibson's theory in this direction is a very natural extrapolation for many reasons. To see something as an affordance is to see it as potentially useful for some purpose or goal. Dewey believed that it was our goals that caused our experience to be tinged with a distinct emotional quality, and saw that quality as being the starting point of all inquiry. If we recall that no one ever drives a car unless she plans to go somewhere, and no one goes somewhere unless she has a reason, We see there is no reason to stop the structuring principle of affordances at the level of simple motions like walking and balancing. The act of driving is itself an affordance to getting somewhere, and so on. As a scientist, Gibson was obligated to confine himself to the study of those relatively primitive affordance structures that could be studied in laboratory conditions. But if we are to confront the traditional problems of epistemology with new solutions, we have to be willing to extrapolate to the higher cognitive and/or experiential functions that are the subject matter of epistemology. And when we do this with the concept of affordances, we end up with something very much like Dewey's concept of experience.


            In real life skills are never separated from goals, and goals are never separated from emotions. It is, of course, necessary to separate them for purposes of analysis, for a given skill can be practiced in service of a variety of different goals, and we can feel many different emotions about the same goal. We can hammer in a nail to build a house or build a coffin, and we can feel either happy or sad about building either or both. But no one ever hammers in a nail for no reason at all (even hammering in a nail to prove that it was possible to hammer in a nail for no reason, would be doing it for that reason.) And whatever emotions we feel about anything are conditioned by how that occurrence affects our goals. If we have conflicting emotions about an occurrence, it is because we have conflicting goals. As far as I know, we don't have enough knowledge about the nervous system, or enough success with AI modeling projects, to provide any real evidence that emotions and goals are constituted by connectionist vector transformations. But given that they seem to flow so seamlessly into skills and abilities,  it seems likely that they both share a common biological architecture.  And if they did, it would explain why emotions, and the skilled habitual responses that are shaped by our goals and emotions, seem to have an independent existence from our verbalizable thoughts.


            For those who take ordinary language seriously, I would point out that the word "feelings" refers to both sensations and emotions, and that we feel far more pain at the death of a loved one than at the pricking of our fingers. What Dewey is suggesting is that this original seamless concept of "feeling" is the true one, and that the separation of  "physical feelings" that supposedly tell us about the world from "emotional feelings" that supposedly tell us only about our mental states is a philosopher's artifact. Gibson gives strong evidence that a particular retinal or proprioceptive signal does not create a feeling all by itself. It only becomes part of our mental life when it becomes part of a system of affordances. The only real difference between Dewey and Gibson on this point is that Dewey is willing to see the most sophisticated and uniquely human aspects of experience as also being systems of affordances: Not only driving a car, as Gibson suggested, but listening to or performing in a symphony; cooking or eating a fine meal in a restaurant. And because Dewey did not have to fear professional ostracism if he talked about those aspects of human experience that are not describable as behavior, he was able to account for nuances that Gibson was professionally compelled to avoid. This is why he was able to talk about a single goal directed activity having a unifying felt quality, whose existence we can acknowledge (but not communicate or capture) with single ejaculative expression like "good!" or "alas". (Dewey 1931 p.101). And when the goal is abandoned or achieved, the experience comes to an end, and another one with a different quality seamlessly begins.[9]


            Once we have abandoned the hope that we can get experience to act as a foundation for knowledge if we divide it up into the smallest possible bits, we can see what should have been obvious to us all along: Each of the previously listed experiences presents itself to us as a whole. Each of these wholes is divisible, of course, but that does not mean they were divided when we first experienced them.  That this is true even of experiences which are of relatively short duration can be seen by the following example, familiar to any musician. If one learns a four bar melody, and there is something wrong with one's execution of one part of it, it is usually necessary to divide it into smaller parts, so as to inquire into exactly what is wrong. If we learned melodies by storing the notes one at a time and then stringing them together, it should be easy to divide a melody in half with a simple internal command. In fact, playing half the melody is like learning a whole new melody, and when we finally do learn it, it is because we have grasped the  noticeably different qualitative feel of the newer shorter melody. Similarly, most people who can drive cars could not rattle off the list of affordances that the car driving experience reveals to someone like Gibson who inquires into the experience. And the fact that car driving experience really is constituted by those affordances doesn't mean we were experiencing it that way all along. It just means that the experience of driving the car was the starting point for Gibson's inquiry, it does not mean that it provides a foundation for that inquiry.  The experience does not remain firm and fast, the way a sense datum supposedly did. Inquiring into the experience will change it, hopefully for the better; that is why we conduct inquiries.


            I have said relatively little about inquiry, even though it is the other half of the dichotomy that is the central theme of this paper. And what I have said may have given the misleading impression that there is an unbridgeable difference in kind between inquiry and experience. In fact, knowing how to conduct an inquiry is a skill that must be fundamentally governed by similar principles that govern other knowing-how abilities. And conducting an inquiry is itself an experience that has a quality all its own, a quality often very difficult to fully appreciate for those of us who live so close to it.  It seems inevitable that eventually someone will figure out  how to apply the principles of Gibson and the Connectionists to show how a system of affordances can be built up that makes inquiry possible, and a few steps have already been made in that direction.[10] The focus for such a meta-inquiry would certainly be that ability which makes us so much better at inquiry than any other animal i.e. language. This search is the philosopher's stone (and hopefully, eventually, the Rosetta stone) of connectionist research, and if successful, it would blur the distinction I have tried so hard to clarify in this paper. But such a blurring would be appropriate for that sort of inquiry, even if it would confuse the presuppositions of this one. For most of philosophy's history, all human experience has been seen as a kind of continuous spontaneous knowing, so perhaps it is high time that philosophers like Dewey, Heidegger and Merleau-Ponty have turned the tables, and now see knowing as a particular kind of experienced activity, rather than the only kind of experience there is.           



[1]Here, I think, we see the origins of Rosenthal's "higher order thought" theory of consciousness


[2] One person who has effectively critiqued this view of the pragmatists is Susan Haack, especially in her  1997 review "Vulgar Rortyism".


[3]There are limitations to the flexibility of the carving process, but I don't believe it is fully known what they are yet. I've heard it said in conversation that a single array of nodes cannot produce the same response to two regions that are not topologically joined in some way, but that such a response can be produced by two arrays of nodes in successive layers. I would welcome any further information on this topic, but do not feel that I need it for this particular paper. My point is the same, regardless of whether the flexibility in creating computational spaces is limitless, or merely very very great.


[4] see Hilditch 1995 pp. 127-140 and Merleau-Ponty 1962 p. 130)


[5] Note that this passage equivocates on whether sensory experience is knowledge or not. The original passage says sensory experience is not "characterizeable as expressing knowledge", the footnote  says sensory experience is direct non-inferential knowledge. This tension dissolves if we take my suggestion that direct knowledge is not linguistic but is still knowledge.


[6] Willem Devries pointed out to me that there is a strong pragmatist position implied by the qualifying phrase "in the dimension of describing and explaining the world". Devries claims that Sellars acknowledged that the manifest image  had a reality of its own because it  is "the framework in terms of which man came to be aware of himself as man-in-the-world.  It is the framework in terms of which, to use an existentialist turn of phrase, man first encountered himself.  (which is, of course, when he became man)" (1963b p.6) When we do things other than describe and explain the world, the manifest image has a reality for those activities, and a pragmatist interpretation of Sellars could see Sellars as not granting exclusive reality to the world as revealed when we explain and describe. This interpretation sounds very much like Dewey, but I think that there is still an important difference. As far as I can tell, Dewey, unlike Sellars,  did not see science as producing a single unified view even within the dimension of describing and explaining the world. 


[7] Note that despite what Rorty might think, this is not a rejection of metaphysics as such. Dewey is not merely asserting that it is a waste of time to look for underlying metaphysical unity, he is asserting that there is none. This is a specific metaphysical claim which Dewey embraces because it enables him to make better sense out of experience. Dewey does not need to claim to have proved this metaphysical assertion, and I don't think he does. I'm sure Dewey would have acknowledged (perhaps under duress) that it could be the case that reality is all governed by a single underlying system that no one has yet found. But denying that there is  such a system is a more useful assumption because it enables us to give a more robust ontological status to the flux of experience in which we live. For Dewey that is the only sort of justification we can ever have for a metaphysical assertion.


[8] This distinction is actually made in Nesser 1992, but Nesser claims that this is the most effective way of clarifying Gibson's concept of affordance.


[9]Shusterman's criticizes Dewey's claim that all experience has a felt quality because it seems to him to amount to something like a transcendental deduction. However, if we take Dewey's concept of experience seriously, we can see that all of his observations about quality are really empirical, in the radical empiricist sense. To object that they are not empirical in the positivist sense (i.e. testable from the third person perspective) is to beg the question. Shusterman is correct when he says that almost everything Dewey says about experience can be translated into talk about habits and purposes. But to so translate them is to take them out of first person context and put them in third person context, and that makes it impossible for them to explain their intended explanandum.  More scientific data is needed, but we need to figure out how to relate it to the first person perspective, not jettison that perspective altogether.


[10] In "Different ways to Think" Ruth Millikan builds a convincing three stage story about how creatures that had only the simplest knowing-how abilities could gradually evolve more complicated and flexible abilities that would be describable as having inner representations i.e. something like language. Merleau-Ponty outlines a similar hierarchy in his "the Structure of Behavior", which Hilditch describes in his "At the Heart of the World:" (1995).


            1)The simplest kind of motor control is governed by what Millikan calls an "Intentional Signal" and what Merleau-Ponty calls "a syncretic structure".  They both use the same example (the frog's ability to respond to a small object that moves like a fly.), and cite the same defining property of that example: The lack of flexibility to function outside of a particular set of conditions. When a frog sees a small moving object it reflexively shoots out its tongue, and because the object is usually a fly, this usually results in the frog getting fed. As Millikan and Merleau-Ponty describes the cognitive structure of the frog's food locating mechanism, it is not significantly more complicated than a thermostat. And just as a thermostat cannot function once it is taken out of the furnace-control circuitry, so a frog will eat BBs when it is taken out of a pond and put in a laboratory.


            2)The next stage is what Merleau Ponty. calls "Amovable structures". Their connection to Millikan's next stage  is not as clear, but there is a corresponding greater degree of flexibility for both because amovable structures "tie behavior less tightly to specific stimulus configurations" (in Hilditch's words.).  For Millikan, this flexibility emerges when fact and goal icons are separated. For a frog, there is only one possible goal that can be served by the reception of information about  a nearby small moving object.  Input of type A produces output of type B; End of Story.  However, certain higher animals (including, but not limited to, humans) can separate an input signal from a single purpose and see it as a fact distinct from any single goal. Animals with this kind of cognitive structure can make decisions based on the relationships that different stimuli have to each other, rather than just responding to a single kind of stimulus,. the way a frog does.


         3) The last stage is what Merleau-Ponty calls "symbolic structures", which correspond very closely to what Millikan has to say about the essential features of language. The feature of this stage that Hilditch stresses is the fact that symbolic structures make it possible to conceive of an objective world that exists independently from the subjects egocentric perspective. (Which is similar to certain Kantian points Millikan makes about how an awareness of space is cognitively constituted.) Merleau-Ponty also stresses a feature of language similar to Chomsky's concept of generative grammar: the ability to say things with symbols that have never been said before. (The example he gives is musical improvisation, and the ability to establish relationships between marks on paper, muscular movements and sounds.)