Me on Stich on Dennet on Intentional Systems [notes on cognitive science]

04May09

Dennet had the great idea of “formalising” folk psychology by ascribing beliefs, desires and intentions to objects in order to describe and predict their behavior. This is called the intentional stance, in which one predicts the most rational behavior of the object described according with the current beliefs held by it. This means assigning the object the beliefs it ought to have according to its perceptual abilities; the desires it ought to have given its biological needs and finally the behavior that would be rational given the beliefs and desires it holds.

This sounds very good, because we make no commitments about the internal workings of the system nor its design or program. Therefore, if we have two robots designed to act exactly like you, mimicking every single action you do, in the context you do them; they wouldn’t be any different from each other or from you from an intentional point of view. This means that describing an object as an intentional system does not entail anything about its physicochemical nature or functional design, and neither neurophysiology nor ”subpersonal cognitive psychology” could possibly show that the object is not an intentional system. These new concepts are identical with folk psychology, but they are better, since they capture its essential notions. These must be comparable to the older folk notions when it comes to describing ourselves.

However, accepting the intentional stance notions of Belief and Desires (which we will call ISBelief and ISDesire) would not allow us to describe human behavior, since a great deal of the time humans behave quite irrationally. However, the intentional stance assumes perfectly rational systems so attributing inferential failings and inconsistent beliefs to them makes no sense. How would you explain suicides, smokers and so forth? Dennet takes two routes. The first, called by Stich “The hard line” sticks to the idealized notion of intentional systems and tries to minimize the importance of the differences between IS beliefs and intentions and their folk-psychology counterparts. He uses arguments springing up from evolutionary optimality: if an organism is the product of natural selection, we can assume most of its beliefs are true and their belief generation strategies rational. The “soft line” legitimizes human faliability, by deriving “imperfect intentional systems” from the idealized ones explained above. However, this would be like adding a tolerance rule to chess such that any game can be considered legal as long as there are at most k illegal moves of chess.

Stich aims to step away from Dennet’s theory by reshaping it. There are two main points. First, rather than an instrumentalist view of folk psychology, he takes a functional one: belief states are functional states which play a role in the causation of behavior. Second, in ascribing content to belief states, we are not comparing others to an idealistic rational entity, but to ourselves. This makes it possible for three people reading about an earthquake on different sources have the same belief that the earthquake actually happened, and it accounts for the fallibility of human reasoning.

from “Dennet on intentional systems” by Stephen P. Stich
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One Response to “Me on Stich on Dennet on Intentional Systems [notes on cognitive science]”

  1. 1 Ali

    Awesome notes Dario! I’m slowly going through all of them and trying to re-arrange my thoughts… Woot! 😀


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