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by Drew V. McDermott
MIT Press, 2001
Review by Marcel Scheele on Mar 27th 2002

Mind and Mechanism

McDermott has written an excellent essay on the subject of mind. It covers the whole of what nowadays is understood to be the subject matter of philosophy of mind. Roughly, one can say that this consists of the question as to what thinking is and the question as to what consciousness is. Philosophy of mind construed more broadly as the question about the relation between mind and world is not the subject of the book (although any theory of the mind does treat it, if only implicitly, by giving a theory of what the mind is). Also, questions about something like the soul of people or questions similar to this are not treated.

          McDermott is not a philosopher, but an Artificial Intelligence (AI) specialist. That means that he is very knowledgeable about one approach to the topic of cognition. Very often non-philosophers talking more broadly or in a philosophical vein about their topic think it is quite easy to do ‘philosophy of their discipline’. Usually I am not very impressed by the things they write: being good at a subject does not imply being good in the philosophy of that subject. McDermott definitely is an exception to that rule. He has understood many philosophical intricacies of the problems he treats and I think he advances some of the subjects as well, especially in the part about consciousness. Let us therefore see what he does in the book.


          Chapter one introduces the problems it deals with and shows some of the difficulties anyone thinking about the mind encounters. I said above that the main problem is the question what thinking consists in, but the so-called ‘“hard problem” of consciousness is to explain how a physical object can have experiences. This is the problem of phenomenal consciousness.’ (p. 20) The second chapter takes on the problem of thinking. For philosophers and cognitive scientists in general it does not contain many novel insights. It is however interesting to read about the problem from the particular viewpoint of an AI specialist.

          Nowadays it is quite common to conceive of thinking –or of the cognitive apparatus– as a kind of formal symbol manipulating machine. Philosophers tend to call this a functional system; AI experts tend to call it a computational system. However, both conceive of such a system roughly as something that takes input –such input can also be the output of another part of the system– and manipulates it according to certain (formal) rules –such rules are not necessarily deterministic rules. This results in a certain output, which might be behaviour, or serve as input to another part of the system. The AI approach tries to model such processes in order to see whether kinds of intelligent behaviour can be modelled. In that sense the approach McDermott takes in this book is quite interesting, because he has access to particular experiments and AI systems built, which provides insightful examples.


For me chapter 3 contains the core of the book. Here the author goes beyond what is state of the art theory of cognition and tries to give a theory of phenomenal consciousness. The problem is a “hard problem” because of the following: ‘(...) it looks at first as if computational models could never explain phenomenal consciousness. They just don’t trade in the correct currency. They talk about inputs, outputs, and computations, but sensations of any of these things don’t enter in. Hence it seems logically possible that there could be a computer that made exactly the same sensory discriminations as a person and yet experienced nothing at all.’ (p. 94)

          In this review, I will limit myself to stating and explaining some of the core ideas of his theory, without pretending to be able to do full justice to it.

In the first place, McDermott believes that the (kind of) theory contained in chapter two provides enough material for a theory of consciousness. Chapter 3, therefore, is called: ‘A computational theory of consciousness’.

          In the second place, he argues that computational systems can exhibit models that represent states of affairs. A very complex system (or robot) might have models that represent its surroundings in detail, but a very simple system can also have such models, for instance in the case where a computer that keeps inventory of an office building has a model of many of the objects inside the building.

          These kinds of system can also have models of themselves. Again, a complex system might have a model that pictures the self as an autonomously acting agent –we humans are of such complexity. But our inventory-computer also can have a model of itself, being part of the inventory of the building.

          Everything that can be said about consciousness can be put in terms of these self-models. Self-models are the I in the sentence: “I am experiencing pain”.

          In short, McDermott now argues that this notion of self-model can be explained in terms of, and built with, the help of purely computational systems. In that sense a computational system can exhibit a self-model that ‘says’: “I am experiencing pain”.

This is an extremely important first step. A second step needs to be taken, though. Is this “pain experience” a kind of virtual experience or a real (conscious) experience? McDermott first shows in what sense it is a simulated or virtual experience: he shows that it is has to do with beliefs about one’s experiencesin casu one’s self model. So the conscious experience of McDermott’s pain in his knee consists of a model of himself in which a pain in the knee figures, but also a belief about that pain, namely that it is a pain within his self model.

          It is, I believe, relatively easy to accept that this is a necessary condition for having experiences, but is it also sufficient? McDermott believes this is sufficient (in principle at least). He argues that sufficiently complex systems having beliefs about their own phenomenal experiences (i.e. a system exhibiting virtual consciousness) are thereby really experiencing (i.e. exhibit real consciousness).

          If the arguments he gives are correct then he has shown that virtual and real consciousness are the same and he has shown how a computational system can exhibit consciousness. If human minds are such computational systems, then he has given (at least partly) an explanation of consciousness. I do not know whether the theory is viable in the end, but it is one of the best attempts I have read up till now, and at least deserves further research by scientists and philosophers.


After this discussion of his theory of consciousness, he discusses, in chapters four and five, many possible objections to his theory and he works out several details concerning it.


The final chapter ends with some consequences of the theory. What does this theory (or better: what does the truth of this theory) mean for morality, for our worldview in general and for religion? Much of what is being said is not very shocking or new and I will leave it to the reader to decide on the merits.

          Unfortunately, it seems that the pen of the author began to live a life of its own towards the last ten or so pages of the book. Suddenly he says that it is indeed hard or impossible to see a God or morality in such a view of the world, but still it is reasonable to believe in God. This seems to me to be very strange. I’m not arguing that one should not believe in a God or so, but, given what he wrote before, it seems to me strange to call it reasonable.

          But no book is perfect, I guess. This last point does not take away my opinion that the book is very good and a must for anyone wanting to know something about a state of the art theory of the mind.


© 2002 Marcel Scheele


Marcel Scheele is a philosopher. He received his masters degree in the Philosophy of Mind at Leiden University (Netherlands). His thesis was on the functionalist theory of mind. Currently he is doing Ph.D. research at the Delft University of Technology on the philosophy of technology. The research concerns the nature of technical artifacts. It is especially concerned with the question how users bestow different functions on these objects and how this relates to 'the' function of an artifact. The main area's of inquiry to this effect are the notion of function, social ontology, collective intentionality, and meaning. He is also still working in the philosophy of mind.