Monthly Archives: February 2008

Heidegger: Life and Philosophy

This is an interesting documentary mainly on Martin Heidegger’s life, with a little bit of his philosophy thrown in.

Part 2
Part 3
Part 4
Part 5
Part 6

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Thoughts on Representation

I just read an interesting paper by Eric Dietrich and Arthur B. Markman entitled “Discrete Thoughts: Why Cognition Must Use Discrete Representations.” In the paper, they first give a definition of general mental representations and make a distinction between discrete and continuous representations. Then they outline seven arguments for why they think discrete representations are necessary for any system that discriminates between two or more states.

Their definition of general mental representation is I think robust and conceptually useful. They define a representation to be any internal state that mediates or plays a mediating role between a system’s inputs and outputs in virtue of that state’s semantic content. They define semantic content in terms of information that is causally efficacious and in terms of what that information is used for. What this means is that representations have to be a part of mental causation. This approach reminds me a lot of Hofstadter’s work, which I have talked about here. Hofstadter emphasizes how mental representations, which mediate between the environmental stimulus and the behavioral output by virtue of being causal at the appropriate level of analysis. I take Dietrich and Markman to mean the same thing when they say that mental representations must be “psychologically real”. In Hofstadter’s terminology, the symbols must be active.

Next, the authors offers a definition of discrete representation. “A system has discrete representations if and only if it can discriminate its inputs.” If a system categorizes, then it has discrete representations. In contrast, a continuous representation would be more tightly bound to its correspondence with the environment. It would be coupled in such a way that it wouldn’t have the ability to make distinctions between its inputs. This is illustrated by the examples of a watt governor and a thermostat. In a watt governor, the arm angles of continuous representations of the speed of the fly wheel, and in contrast, a thermometer must make an on/off discrimination of the continuous representation of the varying bimetal strip. The discrete representation supervenes on the continuous representation.

Finally, the authors give seven arguments why cognition requires discrete representations. I won’t go over the arguments in detail, I will just list a brief summary taken from the text.

1. Cognitive systems must discriminate among states in the represented world.
2. Cognitive systems are able to access specific properties of representations.
3. Cognitive systems must be able to combine representations.
4. Cognitive systems must have some compositional structure.
5. There are strong functional role connections among concepts in cognitive systems.
6. Cognitive systems contain abstractions.
7. Cognitive systems require non-nomic representations.

In their conclusion the authors discuss the claim that it follows from the presence of discrete representations in the cognitive system that the best paradigm for cognitive science must be computationalism. They argue that any system that utilizes discrete representations must be finite and has deterministic transitions between states which can be constructed into an algorithm. Thus, the mind can be described as a computationalism system. I think this is a clever argument and places computationalism into its proper role as the dominant paradigm in cognitive science. Until conflicting evidence shows that when it comes to general mental phenomena there is a better methodological framework, we shouldn’t deny computationalism’s place as the best explanatory paradigm.

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Pragmatic and Epistemic Action

In a 1994 paper entitled “On Distinguishing Epistemic From Pragmatic Action” published in Cognitive Science, David Kirsh and Paul Maglio make an fascinating distinction between actions that change the world(pragmatic) and actions that change the nature of our mental tasks(epistemic). That sounds interesting you say, but how did the researchers go about showing such a distinction? By playing Tetris! Or rather, watching other people play Tetris.

I am sure almost all of you are familiar with the game Tetris so I won’t bother going into too much detail describing how one plays it. Basically, various geometric shapes called “zoids” fall one at a time and you have to arrange them in a row. One is allowed to rotate the zoids to best fit them into the virtual environment. The key idea behind using Tetris as their methodological domain was that Tetris is requires real-time, split-second interactive cognitive and perceptual performance. This allowed the researchers to tease out how people offload cognitive computation onto the external world in order to ease up the difficulty of the mental task at hand. This sort of external manipulation is called epistemic action and as I mentioned above, is distinguished from an action that merely seeks to change the nature of the world. Epistemic actions improve cognition by doing the following:

Reducing the memory involved in mental computation, that is, space complexity;

Reducing the number of steps involved in mental computation, that is, time complexity;

Reducing the probability of error of mental computation, that is, unreliability.

Kirsh and Maglio found that advanced Tetris players perform a variety of epistemic actions to reduce their internal computational effort. In contrast to less-advanced players who rotate the zoids in their head, advanced players would physically rotate the zoids. This seemingly simple action changes the way the mind handles the computational task of rotating the zoids in the game and thus allows the player to manipulate the virtual world with more reliability and speed.

Such data suggests that standard theoretical frameworks in cognitive science might not be enough to explain the full extant to which humans utilize the external environment in ways that alter their mental landscape to improve cognitive performance. Instead of breaking up the world into a dualism of physical space and information-processing space, it might be more theoretically useful to have a more unified and fluid space where both pragmatic and epistemic actions can take place. This approach gives more credence to the idea that we are fundamentally in the world, embedded and embodied, with a perceptual and cognitive repertoire that doesn’t make hard and fast distinctions between the inner and outer realms.

Reference:

Kirsh, D., & Maglio, P (1994) On Distinguishing Epistemic from Pragmatic Action. Cognitive Science: A Multidisciplinary Journal, Vol. 18, No. 4: pages 513-549

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Controllers?In my brain?

I have been hearing a lot of buzz lately about Asim Roy’s newly published paper Connectionism, controllers, and a brain theory. What is all the hype about? Well, Roy claims to be offering a “new theory for the internal mechanisms of the brain.” Sounds exciting doesn’t it? What could Roy be proposing that is so revolutionary? Roy proposes that…wait for it… some parts of the brain control other parts! I suppose most of you aren’t exactly blown away, and I certainly wasn’t either.

Roy’s rhetoric is obviously pretty overblown, but let us give him the benefit of the doubt and move on to his actual arguments. He starts off by claiming that connectionist theory “postulates that the brain does not have controllers in it.” He quotes Rumelhart, Hinton, and McClelland as saying “there is no central executive overseeing the general flow of processing.” Seems pretty non-controversial to me though. They seem to be merely saying that there isn’t a homunculus in the system, controlling everything with a immutable Will. Philosophy 101. So what is Roy actually arguing against? A straw man? Sort of, but not quite. Roy argues that in connectionist models, there is a “controller” in the system that controls the learning algorithms and thus connectionist theories are essentially rooted in control-theoretic modeling.

But, as peter over at conscious entities mentioned, connectionist theorists haven’t exactly gotten to the point where they are proposing a general architectural model of how the brain works. It seems entirely plausible that when connectionist models get to that point of complexity, they wouldn’t hesitate to propose that some modules control other modules. Otherwise, I don’t see how one could get a theory that modeled high-level cognition. The way Roy structured his arguments, I don’t think anyone would argue against the idea that “there are parts of the brain that control other parts.” Furthermore, Roy himself undermines his claim for proposing a “new paradigm” when he says things as trivially obvious as:

It should be pointed out that this theory does not posit that there is a single executive controller in the brain. [b]Instead it envisions “multiple distributed controllers” controlling various subsystems or modules of the brain[/b]. The main argument of the paper that connectionists use “executive controllers” is only pointing out that their algorithms use a “central controller.” But different modules in the brain using connectionist-type learning can have their separate controllers.

I’d also like to point out that Roy was beaten by at least ten years on his emphasis of controllers. In his 1997 book Being There, Andy Clark says:

The idea here is that the brain should not be seen as primarily a locus of inner descriptions of external states of affairs; rather, it should be seen as a locus of inner structures that act as operators upon the world via their role in determining actions…This perspective leads to a rather profound shift in how we think about mind and cognition-a shift I characterize as the transition from models of representation as mirroring or encoding to models of representation as control

So contrary to Roy’s strong rhetoric, people sympathetic to connectionist theory such as Clark have been thinking about the mind and the brain in terms of action-oriented controllers for many years. In conclusion, I agree with Roy’s essential argument that there are parts of the brain that control other parts of the brain, but I don’t think this is a revolutionary of a paradigm as he thinks it is. Roy himself quotes from all over the neuroscience literature showing that it is riddled with control-theoretic terms, and by his own argument, he shows that connectionist theory is also already steeped in control theory. Surely, the connectionists themselves understand this. So who is Roy arguing against here?

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Perception and Action: Context-specificity

Research by Adolph, Eppler, and Gibson on infant responses to slopes has provided insight into the interplay between perception and action. In the research, infants with different forms of mobility(crawlers or walkers) were encouraged to ascend and descend slopes with different degrees of steepness. The walkers were wary of slopes of 20 degrees or more whereas the crawlers fearlessly attempt slopes of 20 degrees or more. As the crawlers increased in experience, they learned to avoid descending the steeper slopes. However, when crawlers first begin to walk this avoidance pattern seems to disappear and they again plunged down the steep slope without hesitation.

These results seem to indicate that the perceptual knowledge that infants gain about the world is action-specific. Infants do not learn about slopes in general but rather, they learn about slopes-and-crawling and then slopes-and-walking. Research along these lines paints a picture of perception as being for specific action-routines. Thus, theoretical frameworks in cognitive science should be geared towards “motocentricity” rather can “visuocentricity”. This re-conceptualization ties in with what James Gibson posited almost 30 years ago in his book The Ecological Approach to Visual Perception: that perception is tied in what we can do with perceptual information. Our perception of a chair is intimately coupled with the fact that chairs are for sitting. Gibson claimed that these perceptual affordances for action are directly perceived in the environment around us. So when an infant looks at a slope, he perceives that the slope affords for falling. The only trouble is putting such information about the environment into use using the context-specific motor schemas available to the infant.

References:

Karen E. Adolph, Marion A. Eppler, Eleanor J. Gibson (1993) Crawling versus Walking Infants’ Perception of Affordances for Locomotion over Sloping Surfaces Child Development, Vol. 64, No. 4 (Aug., 1993), pp. 1158-1174

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Reductionism or Holism? MU!

MU

This picture was drawn by Douglas Hofstadter for his classic dialogue “Prelude…Ant fugue” in his masterful Godel, Escher, and Bach. In the dialogue he asked a simple, yet highly illuminating question: what does the picture say?

On the top level, it says “MU”, alluding to the Zen parable of Joshu and the dog. In this parable, a monk asks Joshu “does a dog have Buddhe-nature?” Joshu, with immediate fervor, replies “MU!”, which basically means that Joshu denied the legitimacy of the question. He “unasked” the question. The relevance of the parable is made clear when one attempts to answer the above question: what does the picture say? One cannot simply assert that it says “MU”, although on the top and bottom levels it says as much.(You can’t see it in the above copy, but the individual letters are made out of tiny iterations of “mu”). That would be too simplistic of an answer, although it is trivially “true”.

The beauty of Hofstadter’s diagram is only apparent after you let the meaning of the parable sink in. Do all questions have definite answers? Can we really ask questions like “Is the key approach to the mind reductionist or holist?” and expect simple answers? Is it wiser to instead “unask” such questions? Perhaps that question should be unasked as well!

I love this diagram on multiple levels, which is fitting I think, so I thought I would share it with you all. Please spend the time to ponder on the question of what the picture reallysays, and see if you come to the same conclusion as Joshu.

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What does it mean to be human?

What does it mean to be a human? What is being? What is the difference between the being of humans and the being of non-humans?

These are all important and difficult to answer questions. Martin Heidegger was one philosopher who took it upon himself to attempt to answer some of these questions. His aim was to work out the general meaning of being and to do so concretely. Did he succeed? Some would say yes, others no. In this post, I’d like to sketch out a part of his answer, focusing on the the last question: the difference between the being of humans and the being of non-human animals i.e. the ontological difference.

The distinction between being and beings is there, latent in [humans] and [their] existence, even if not in explicit awareness. The distinction is there; that is to say, it has the mode of being of [humans]: it belongs to existence. Existence means, as it were, “to be in the performance of this distinction.” Only a soul that can make this distinction has the aptitude, going beyond the animal’s soul, to become the soul of a human being…we call the distinction between being and beings, when it is carried out explicitly, the ontological difference.

I’d like to concentrate on the part I made bold. This is crucial to his definition of what it means to be a human being[Dasein]. Essentially, humans comport themselves toward their own being. Another way of putting this awkward phrase is that humans take a stand on their own being. This is what “being in the performance of [the ontological difference]” means. Through the particular ways in which humans act within the world, we make this ontological difference a part of our existential mode of being. This means we always perceive/conceive and act in the world in terms of the difference between being and beings, between the the ontological being of ourselves and the entities which make up the physical world. There is something-it-is-like to be us, and that something has to do with how we already pre-ontologically make a distinction between being and beings.

Whether or not you think of all this is useless metaphysical mumbo-jumbo or an historical attempt to answer one of the most important questions in philosophy is up to you, but hopefully I made it clear that Heidegger was at least an original thinker.

edit: I have updated the original post to fix the inconsistencies pointed out by Roman.

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