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The logic of mind
Internafional
Journal
of Psychophysiolow
1 (1983) 125- 129
125
Elsevier
Book Reviews
The Logic of Mind by R.J. Nelson D. Reidel Publishing Company, pp.) ISBN 90-277-1399-5
London, 1982. (392
This book is one of a series published by Reidel with the aim of providing an overview of the best current work in epistemology and in the methodology and philosophy of science. It is an ambitious project, and this is an ambitious book. In it, Nelson attempts to present a mechanistic philosophy of mind, by which is meant the view that mental processes operate by a system of computational (recursive) rules. Over and above this general view, Nelson argues that the mind should be thought of as a Non-deterministic Finite Automation (NFA). An NFA is a rule-governed system with signal inputs, control and output; the system can be in a limited (finite) number of states, and the transformation rules from input to output operate probabilistically and are not determined. Rules are of two types, one to perform actions and the other to change an internal (memory) state. Thus NFA are hierarchical and they can be built to any level of complexity. Further, the system acts as an effective process (i.e. the computations extend beyond operations on numbers to symbols and any enumerable processes), and constitutes a true description of mind, since the mind can be said to be realized by such rules. This is a complex argument. Nelson’s approach is to present it in two parts. To begin with (Chapters I-V), he demonstrates what is meant by rule of mind, Turing machine rules and rules of finite automata (only deterministic finite automata are discussed in detail, since they provide clearer examples). This is done in quasi-mathematical format, using functions from set theory. This mechanistic approach is briefly related to similar concepts 0167-8760/83/$03.00
0 1983 Elsevier Science Publishers
B.V.
in psychology (the neuronal networks discussed by McCulloch and Pitts, 1943; computer networks; TOTE hierarchies and the like), and it is contrasted with other philosophies (behaviourism, functionalism and rationalism). Those arguments which are not new (e.g. that behaviourism will not do because the causative role of internal states must be accommodated) provide useful background links for the mechanist’s position. Even more useful are the arguments distinguishing Nelson’s approach from the functionalist-type approaches currently popular in cognitive psychology and artificial intelligence (AI), such as the argument that, since the mind is thought to be literally guided by systems of recursive rules, it is an NFA; also that the functionalist argument that mental operation can be explained in terms of a series of internal states is not akin to a mechanistic explanation, since those states can be subject to analysis and decomposition. After highlighting such differences, though, Nelson does make a reassuring attempt at reconciliation. Many of the differences are surely apparent rather than real, with contrasting approaches addressing different levels of description. The second section of the book (Chapter VI onwards) extends the earlier theoretical outline to attempt to account for intention in behaviour. For Nelson this is an important issue, since it contradicts Bretano’s thesis that the intentional is irreducible. A number of areas are covered (perception, belief and desire, reference and truth, meaning), with, I believe, varying success. This is of course to be expected when such a wide area is tackled; nevertheless, it does reflect the potential of the mechanistic approach. With this breadth of topic, there is much to whet the appetite of researchers in the cognitive and brain sciences, as well as in the philosophy of mind. In particular, in giving a general overview of the mechanistic approach in the first section of the
126
book, a number of insights are provided for those interested in the mathematical modelling of mind. For instance, Nelson’s demonstration that intension can be analyzed will give ammunition for those of us who are consistently challenged by students holding that AI is an ineffective approach to many aspects of human behaviour. Similarly, Nelson’s distinction between machine, (an abstract system of recursive rules) and machine1 (actual machines. such as computers) usefully illustrates that critiques of particular work in the AI field cannot invalidate the general approach. Such distinctions generate a framework for the analysis of mental processes. It is often the case when we formalize our arguments that a number of interesting positions are arrived at as a result of the formalizing process. This is certainly true here. One such position is that the distinction between behaviour and physiological structure is maintained in the mechanistic approach. While the approach seeks to specify particular automata for particular functions, there is no necessary relation between the function of the overall system and the structure (i.e. the rule system) of particular automata. By analogy, there is no absolute correspondence between the function of single neurons in the brain and the output of a neuronal network. The mechanistic approach does not imply either localization of function or reductionism. A further interesting. emerging position is that ‘although it is no doubt true that human language is species specific, the specificity is marked by some rather catastrophic lapse in a measure of complexity and nothing else’ (p. 152). That is, the difference between human language and that established in other animals is thought to be essentially quantitative. This arises because the behaviour of any system could be described as an automaton (from Nelson’s favourite worm analogy to clocks). It follows that the essential differences between species are a function of the complexity of their constituent rule structures. What kind of rule structure is then sufficient to count for human behaviour? Nelson argues that distinguishing features are that the rules must be sufficiently complex to account for intentionality (including language) and that the being has conscious feeling.
There seem some difficulties here. The argument that conscious feeling is a prerequisite of mind is built on the distinction between mental features (cognitions) and mental occurrents (raw feelings). Nelson’s thesis is addressed primarily to the explanation of mental features. It is somewhat more difficult to apply mechanistic concepts to mental occurrents. One possibility is that occurrents are equivalent to automation end states. However, many end states are probably not consciously realized. Also, empirical distinctions between conscious and non-conscious processes are difficult to establish. I for one remain unclear about how consciousness can constitute a necessary part of a scientific theory of mind, though I have no doubt that it is a valid subject for discussion. The Logic of Mind does not baulk from this task. The most serious problems in Nelson’s argument occur when he attempts to account for various psychological phenomena. For instance, perception is conceptualized as extensively reliant on expectation. This appears to be derived from Nelson’s stress on the analysis of intention. The net result is an extreme example of an hypothesis-testing theory of perception (e.g. Gestalt phenomena are attributed to the fitting of local parts to an established wholistic scheme). Those familiar with recent, more empirically-based work in this area may have good reasons to object to this position. However, as Nelson himself is aware, ‘to show that Gestalt perception is possible for a recursive system is not the same thing as a true theory’ (p. 170). Objection to particular realizations of the mechanistic argument should not lead to its complete rejection. In addition to these substantive points, there are problems of style and clarity. For example, the level of description addressed by the theory is not always made evident, though this is an important point. It would have been useful to have had Nelson’s position on the levels of mechanistic description (e.g. p. 74) related to other arguments about levels of theoretical description in the literature (e.g. Marr, 1982). Similarly, analogies to recent work in AI bearing strong relations to Nelson’s automaton account (e.g. Feldman and Ballard, 1982) might have been pointed out.
121
Less importantly, Nelson’s writing style depends heavily on the use of footnotes. Though I have no objections to this in principle, I did find that 35 footnotes in a chapter became rather wearing. Even more annoying was that the footnotes were printed at the end of the book. Given Nelson’s reliance on this device, it would have facilitated reading to have included the footnotes in the text. The book also has an uneasy mixture of dogmatic and declaiming statements (cf. ‘This sustained view of Chomsky’s is being vindicated today in the discovery of the wrong-headedness of exaggerated claims about ‘speech’ in apes’, p. 146 , with ‘(these) remarks are not very systematic and, I am afraid, will tend to be no more than tenuously connected fragments’, p. 305). This had the curious effect of stirring my objections only to disarm them further on. In summary, this is an ambitious, stimulating book, and its less satisfactory aspects are probably forgivable in the light of its aims. Although the book is of interest to a number of disciplines, throughout its reading I was unclear about the particular audience being addressed. From the point of view of the experimental psychologist, many philosophical terms and arguments were stated without introduction, making some points difficult to follow. There are probably also too many false garden paths that the reader is led down along the way. Nevertheless, there is enough meat to make it a useful reference for those wishing to be introduced to mathematical models and AI. I look forward to a second reading.
Feldman, J.A. and Ballard. D.H. (1982) Connectionist Models and their properties, Cognrrioe Sci.. 6: 205-254. McCulloch, W.S. and Pitts, W.H. (1943) A logical calculus of the ideas immanent in nervous activity. Bull. Math. Biophys., 5: 115-133. Marr. D. (1982) Vision, W.H. Freeman. San Francisco.
Glyn Humphreys London, U.K.
Kyoto Symposia (Electroencephalography Clinical Neurophysiology, Supplement 36)
and
Edited by P.A. Buser, W.A. Cobb and T. Okuna Elsevier Biomedical Press, Amsterdam, 480.00 (760 pp.) ISBN O-444-80436-6
1983. Dfl
This book contains the invited contributions to workshops and symposia of the 10th International Congress of Electroencephalography and Clinical Neurophysiology held in Kyoto, Japan in September, 1981. The book is divided into 12 sections dealing with: multiple receptor functions; impaired nerve conduction; neuroplasticity and functional compensation; the assessment of muscle relaxants with electrophysiological techniques: the pharmacology and physiology of kindling; brainstem evoked potentials; functional organization of motor areas; EEG and blood levels of drugs (principally antiepileptic); EEG and psychotropic drugs; data reduction methods in intensive care and long-term surveillance; EEG and respiratory disorders and other risk conditions in infants; and, human factors and hazards in industry. The inclusion of workshop and symposia papers only has resulted in a volume which suffers less from the usual problems of conference proceedings; that is, being a large collection of unrelated, short reports. However, it is still true that many of the chapters cover a very wide area with a very few papers. This is inevitable when a book attempts to cover a general conference rather than a topical conference. Inasmuch as the book is already far-ranging it is surprising that the use of electrophysiology in research on psychopathological states receives virtually no mention. Similarly, there is no section dealing with the areas encompassed within EEG and psychological processes. Assuming that publication of the proceedings of general conferences is worthwhile there are several format changes which could make the end product of greater use to a wider audience. It would be helpful to have an introduction to each section briefly reviewing the context in which the following papers are presented. This has been done
Journal
of Psychophysiolow
1 (1983) 125- 129
125
Elsevier
Book Reviews
The Logic of Mind by R.J. Nelson D. Reidel Publishing Company, pp.) ISBN 90-277-1399-5
London, 1982. (392
This book is one of a series published by Reidel with the aim of providing an overview of the best current work in epistemology and in the methodology and philosophy of science. It is an ambitious project, and this is an ambitious book. In it, Nelson attempts to present a mechanistic philosophy of mind, by which is meant the view that mental processes operate by a system of computational (recursive) rules. Over and above this general view, Nelson argues that the mind should be thought of as a Non-deterministic Finite Automation (NFA). An NFA is a rule-governed system with signal inputs, control and output; the system can be in a limited (finite) number of states, and the transformation rules from input to output operate probabilistically and are not determined. Rules are of two types, one to perform actions and the other to change an internal (memory) state. Thus NFA are hierarchical and they can be built to any level of complexity. Further, the system acts as an effective process (i.e. the computations extend beyond operations on numbers to symbols and any enumerable processes), and constitutes a true description of mind, since the mind can be said to be realized by such rules. This is a complex argument. Nelson’s approach is to present it in two parts. To begin with (Chapters I-V), he demonstrates what is meant by rule of mind, Turing machine rules and rules of finite automata (only deterministic finite automata are discussed in detail, since they provide clearer examples). This is done in quasi-mathematical format, using functions from set theory. This mechanistic approach is briefly related to similar concepts 0167-8760/83/$03.00
0 1983 Elsevier Science Publishers
B.V.
in psychology (the neuronal networks discussed by McCulloch and Pitts, 1943; computer networks; TOTE hierarchies and the like), and it is contrasted with other philosophies (behaviourism, functionalism and rationalism). Those arguments which are not new (e.g. that behaviourism will not do because the causative role of internal states must be accommodated) provide useful background links for the mechanist’s position. Even more useful are the arguments distinguishing Nelson’s approach from the functionalist-type approaches currently popular in cognitive psychology and artificial intelligence (AI), such as the argument that, since the mind is thought to be literally guided by systems of recursive rules, it is an NFA; also that the functionalist argument that mental operation can be explained in terms of a series of internal states is not akin to a mechanistic explanation, since those states can be subject to analysis and decomposition. After highlighting such differences, though, Nelson does make a reassuring attempt at reconciliation. Many of the differences are surely apparent rather than real, with contrasting approaches addressing different levels of description. The second section of the book (Chapter VI onwards) extends the earlier theoretical outline to attempt to account for intention in behaviour. For Nelson this is an important issue, since it contradicts Bretano’s thesis that the intentional is irreducible. A number of areas are covered (perception, belief and desire, reference and truth, meaning), with, I believe, varying success. This is of course to be expected when such a wide area is tackled; nevertheless, it does reflect the potential of the mechanistic approach. With this breadth of topic, there is much to whet the appetite of researchers in the cognitive and brain sciences, as well as in the philosophy of mind. In particular, in giving a general overview of the mechanistic approach in the first section of the
126
book, a number of insights are provided for those interested in the mathematical modelling of mind. For instance, Nelson’s demonstration that intension can be analyzed will give ammunition for those of us who are consistently challenged by students holding that AI is an ineffective approach to many aspects of human behaviour. Similarly, Nelson’s distinction between machine, (an abstract system of recursive rules) and machine1 (actual machines. such as computers) usefully illustrates that critiques of particular work in the AI field cannot invalidate the general approach. Such distinctions generate a framework for the analysis of mental processes. It is often the case when we formalize our arguments that a number of interesting positions are arrived at as a result of the formalizing process. This is certainly true here. One such position is that the distinction between behaviour and physiological structure is maintained in the mechanistic approach. While the approach seeks to specify particular automata for particular functions, there is no necessary relation between the function of the overall system and the structure (i.e. the rule system) of particular automata. By analogy, there is no absolute correspondence between the function of single neurons in the brain and the output of a neuronal network. The mechanistic approach does not imply either localization of function or reductionism. A further interesting. emerging position is that ‘although it is no doubt true that human language is species specific, the specificity is marked by some rather catastrophic lapse in a measure of complexity and nothing else’ (p. 152). That is, the difference between human language and that established in other animals is thought to be essentially quantitative. This arises because the behaviour of any system could be described as an automaton (from Nelson’s favourite worm analogy to clocks). It follows that the essential differences between species are a function of the complexity of their constituent rule structures. What kind of rule structure is then sufficient to count for human behaviour? Nelson argues that distinguishing features are that the rules must be sufficiently complex to account for intentionality (including language) and that the being has conscious feeling.
There seem some difficulties here. The argument that conscious feeling is a prerequisite of mind is built on the distinction between mental features (cognitions) and mental occurrents (raw feelings). Nelson’s thesis is addressed primarily to the explanation of mental features. It is somewhat more difficult to apply mechanistic concepts to mental occurrents. One possibility is that occurrents are equivalent to automation end states. However, many end states are probably not consciously realized. Also, empirical distinctions between conscious and non-conscious processes are difficult to establish. I for one remain unclear about how consciousness can constitute a necessary part of a scientific theory of mind, though I have no doubt that it is a valid subject for discussion. The Logic of Mind does not baulk from this task. The most serious problems in Nelson’s argument occur when he attempts to account for various psychological phenomena. For instance, perception is conceptualized as extensively reliant on expectation. This appears to be derived from Nelson’s stress on the analysis of intention. The net result is an extreme example of an hypothesis-testing theory of perception (e.g. Gestalt phenomena are attributed to the fitting of local parts to an established wholistic scheme). Those familiar with recent, more empirically-based work in this area may have good reasons to object to this position. However, as Nelson himself is aware, ‘to show that Gestalt perception is possible for a recursive system is not the same thing as a true theory’ (p. 170). Objection to particular realizations of the mechanistic argument should not lead to its complete rejection. In addition to these substantive points, there are problems of style and clarity. For example, the level of description addressed by the theory is not always made evident, though this is an important point. It would have been useful to have had Nelson’s position on the levels of mechanistic description (e.g. p. 74) related to other arguments about levels of theoretical description in the literature (e.g. Marr, 1982). Similarly, analogies to recent work in AI bearing strong relations to Nelson’s automaton account (e.g. Feldman and Ballard, 1982) might have been pointed out.
121
Less importantly, Nelson’s writing style depends heavily on the use of footnotes. Though I have no objections to this in principle, I did find that 35 footnotes in a chapter became rather wearing. Even more annoying was that the footnotes were printed at the end of the book. Given Nelson’s reliance on this device, it would have facilitated reading to have included the footnotes in the text. The book also has an uneasy mixture of dogmatic and declaiming statements (cf. ‘This sustained view of Chomsky’s is being vindicated today in the discovery of the wrong-headedness of exaggerated claims about ‘speech’ in apes’, p. 146 , with ‘(these) remarks are not very systematic and, I am afraid, will tend to be no more than tenuously connected fragments’, p. 305). This had the curious effect of stirring my objections only to disarm them further on. In summary, this is an ambitious, stimulating book, and its less satisfactory aspects are probably forgivable in the light of its aims. Although the book is of interest to a number of disciplines, throughout its reading I was unclear about the particular audience being addressed. From the point of view of the experimental psychologist, many philosophical terms and arguments were stated without introduction, making some points difficult to follow. There are probably also too many false garden paths that the reader is led down along the way. Nevertheless, there is enough meat to make it a useful reference for those wishing to be introduced to mathematical models and AI. I look forward to a second reading.
Feldman, J.A. and Ballard. D.H. (1982) Connectionist Models and their properties, Cognrrioe Sci.. 6: 205-254. McCulloch, W.S. and Pitts, W.H. (1943) A logical calculus of the ideas immanent in nervous activity. Bull. Math. Biophys., 5: 115-133. Marr. D. (1982) Vision, W.H. Freeman. San Francisco.
Glyn Humphreys London, U.K.
Kyoto Symposia (Electroencephalography Clinical Neurophysiology, Supplement 36)
and
Edited by P.A. Buser, W.A. Cobb and T. Okuna Elsevier Biomedical Press, Amsterdam, 480.00 (760 pp.) ISBN O-444-80436-6
1983. Dfl
This book contains the invited contributions to workshops and symposia of the 10th International Congress of Electroencephalography and Clinical Neurophysiology held in Kyoto, Japan in September, 1981. The book is divided into 12 sections dealing with: multiple receptor functions; impaired nerve conduction; neuroplasticity and functional compensation; the assessment of muscle relaxants with electrophysiological techniques: the pharmacology and physiology of kindling; brainstem evoked potentials; functional organization of motor areas; EEG and blood levels of drugs (principally antiepileptic); EEG and psychotropic drugs; data reduction methods in intensive care and long-term surveillance; EEG and respiratory disorders and other risk conditions in infants; and, human factors and hazards in industry. The inclusion of workshop and symposia papers only has resulted in a volume which suffers less from the usual problems of conference proceedings; that is, being a large collection of unrelated, short reports. However, it is still true that many of the chapters cover a very wide area with a very few papers. This is inevitable when a book attempts to cover a general conference rather than a topical conference. Inasmuch as the book is already far-ranging it is surprising that the use of electrophysiology in research on psychopathological states receives virtually no mention. Similarly, there is no section dealing with the areas encompassed within EEG and psychological processes. Assuming that publication of the proceedings of general conferences is worthwhile there are several format changes which could make the end product of greater use to a wider audience. It would be helpful to have an introduction to each section briefly reviewing the context in which the following papers are presented. This has been done