On the Philosophy of Cognitive Science
I - INTRODUCTION
The psychophysical dualism or mind-body distinction is the counterposition between two essentially irreducible elements: soul and body. Such dualism implies, as we will show, the more discussed issue of philosophy of cognitive science and philosophy of mind: the mind-body problem (MBP, henceforth) whose the enunciation is: How is possible the mind-body relation?
The dualism and the MBP were originally created by Descartes in the Metaphysical Meditations and developed by the tradition of modern philosophy. Our communication is composed of three parts:
II - MIND-BODY PROBLEM AND THE CARTESIAN DUALISM
In the main work of René Descartes, Meditationes de Prima Philosophia (1641), the french philosopher had estabilished the distinction between soul and body and formulated the MBP. The order of reasons, that was proposed by Descartes in construing the MBP, may be expounded as follows:
1 - The principle of hyperbolic doubt (every proposition having no immediate evidence must be false) has its limit defined by the cogito aperception. Such aperception represents the fist truth: "I think, then I exist".
2 - The proof of the soul's existence represented by the cogito gives the possibility for the perception of the idea of God that is associated to the principle of causality in order to proof the God's existence. "God exists" is the second main truth.
3 - Helped by the second truth, Descates proofs such things' existence by showing that the things may exist independently of the soul's imagination because God has always created things. Then he deduces the third truth: "There can exist things".
According to first and third truths, Descartes concludes that soul and body are really distinct substances, that is, the existence of each one may be conceived in a clear and distinct manner. Nevertheless, in the sixth meditation, Descartes defines the natural feeling by means of which we can confirm the natural union of the body with the soul. In this sense, soul and body are not clearly distinct substances but they form a unique and total substance. Such a substance is composed by a complex mind-body mixture. But how can two different substances interact in a unique and total substance called man? This question is called the MBP.
The dualist theories of mind are based on the cartesian dualism. The British philosopher of the Oxford Group, Gilbert Ryle, in the book The concept of Mind (1949), had drawn fundamental critics to the dualist theories. Ryle utilized the analytic examination of natural language that makes possible the deconstruction of what he called the Descartes'Myth .
The main arguments of the Ryle's criticisms are:
1 - The category-mistake. The dualist doctrine establishes a polar opposition between mind and body. At the language level, the mental properties are logical negations (in Aristotelian sense) of the physical properties. So they belong, in accordance with the concept of category, to the same logical types, given that the expressions that are used for the descriptions of mental events are always mere negatives of the expressions used for the descriptions of material events. Ryle then says that such form of use implies a categorical mistake. For the descriptions of mental events do not properly belong to the categories used for describing the corporeal events. Such a kind of mistake turned out to be, from the Rylean standpoint, the dogma of the mental ghost in the corporeal machine. Then, dualist doctrines are mythic in a analytical sense.
2 - In order to dissolve the cartesian myth embedded in all philosophical speculations on the nature of mental events, Ryle had suggested the logical analysis of natural language and the correction of the categorical mistakes that are sunk in the ordinary discourse. Mental events properly belong to the category of relations instead of belong to the category of substance.
3 - From the dissolution of the cartesian myth follows the dissolution of the mind-body distinction and, hence, the dissolution of the MBP, since from the logical analysis of language, no real problem remains. We had only a pseudo-problem.
III - THE PRINCIPLE OF EMBODIMENT OF MIND
Following the rylean critics, we have suggested:
1 - Do not consider the cartesian dualism as it was formulated in the context of meditations, because such dualism implies the MBP. Hence to adopt another solution by the means of another formulation of the MBP.
2 - To start on the idea that the mind is not an extra-physical entity but an emergent organization, in a sense that will be explained. Now the new problem concerns with the nature of the organization of mind.
3 - To insert the organizational view of mind in the cognitivist studies, that is to say, in the neural networks in which mind is considered as corporeal organizations, i.e., the organization of brain neurons. In the neural network models of mind, the organization of the bodily parts is functional because the mental states are functions of brain states as a whole. So we have not a dualistic approach to MBP, but a monistic one (functionalist and materialist, indeed).
Then with an appropriate elaboration of a neural network model or connectionist model we can obtain a solution to the MBP in the context of cognitive science. The computational simulation of the functional connectionist organization of mind could make us understand how the functional properties of a brain-like organization could perform cognitive tasks.
The scientific approach to the MBP requires a principle, contained in the functionalist-materialist theory of mind, first elaborated by the physician and neurologist Warren MacCulloch (1959), the principle of embodiment of mind. Such a principle is fundamental regarding the connectionist models. In order to enunciate the principle, we now consider, in a quick manner, the connectionist approach to mental phenomena.
According to the connectionists (see Gonzales, 1990), the basic parts composing the neural network model are similar to the brain neurons; such parts are neuron-like units. Mind is characterized by a brain-like organization that changes, accordingly some natural laws, when the environment changes.
Roughly speaking, it is widely accepted in the neurophysiological studies that the brain neural functions change according to the world changeness. The connectionist model is elaborated in order to preserve functional-neurophysiological relations between the brain and world, and this under two conditions:
1 - The mental states are not reducible to the whole organization formed by the neuron-like units;
2 - The mental states are not produced by some extra-physical thinking entity.
The middle-way between the two conditions (belonging respectively to the materialist reducionist and dualist views of mind) above presented is, according to the connectionist, is the emergentism. According to emergentism (see, for example, Nagel, 1961) mental states may be considered hypothetically as emergent properties of the brain's organization. In the connectionist models, given some type of organization, the emergent properties can occur. What sort of organization gives origin to emergent properties? If the organization, for the emergentists, does not depend upon some ontologically independent entity, then the organisation must be made by itself, that is, there must be some kind of self-organization in the neural network models.
So we can define the principle of embodiment of mind (PEM, henceforth) as follows:
The mental states must be emergent properties of the self-organization of the brain neurons.
Such definition has three basic components: organization, self-organization and emergent properties. The components of the PEM are underlaid by some philosophical concepts that have to be discussed when we use it in the cognitivist studies.
IV - A PHILOSOPHICAL ANALISYS OF PEM
Here we shall approach the scientific solution to the MBP by means of the conceptual analysis of PEM. The concepts are these:
1 - According to the cybernetician W.R. Ashby, the connectionist functional organization is defined on the basis of degree of connectivity of the brain-like system (see Ashby, 1962). So within the connectionist theory of mind, we may interpret Ashby's concept in this way:
The organization of the brain like-units of a neural network is measured in degrees of connectivity of a brain-like system.
2 - The self-organization of the physical units, according to Ashby, is defined in terms of a connective self-referentiality (see Ashby, 1962). Such type of connectivity means that all the connections among the system's parts must be made by the system without any external supply. In the case of the connectionist systems, we could propose that:
The degree of self-organization of a neural network is given by the level of self-connectivity that system can realize under some environmental conditions.
3 - Finally the concept of emergent properties. According to Nagel ( see Nagel, 1961), an emergent property p of a system S formed by the parts a 1,..., a n is such that, from the predictable class P of properties deduced from the relation R between parts, it is not possible to predict p . So the connectionistic formulation of such concept may run as follows:
The degree of emergence in a connectionist system is given by an emergent property subset which is deduced from the relation R defined in terms of degree of self-organization.
The three concepts defined above summarize the complete characterization of the PEM. It is clear that both physicalism and naturalism underlie the PEM. But a philosophical remark could be posed here: Are all the cognitive states of mind natural-law-governed states? The point of such a remark conerns with the limits of a reductionistic theory of the mind.
The PEM, that is presupposed in the connectionist approach, can be considered as methodological reductionism folded in three parts:
- Reduction of biological states to physical states;
- Reduction of cognitive states to biological states;
- Reduction of cognitive states to physical states.
Such reductionism is related to the disciplinary autonomy of the scientific fields in cognitive sciences. The limits of the methodological reductionism are brought into consideration naturally, by means of the validation of the interdisciplinary methodological hypothesis in Cognitive Sciences (see, for example, Gardner 1987). Such a hypothesis can be stated as follows:
The interdisciplinary study of mind can afford the progress in cognitive science as a whole.
But could a reducionist approach to mind be really interdisciplinary in a methodological sense? Such a question will, in our viewpoint, pose new challenges to the emergence of the cognitive science as a result of interdisciplinar co-operation among cognitive sciences.
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