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Mind & Morals

Philosophizing about the Mind

Massimo Pigliucci takes a brief look at the history and current schools of philosophy of mind.

I have had the idea of writing this article in mind for some time now, and yet it is not entirely clear what this very sentence might mean. Is a mind distinct from ideas that somehow float inside it? Am I a different thing from my mind? Is there any interesting sense in which my mind is distinct from my brain and all its sensorial inputs and motory outputs? Arguably, these questions made no sense before René Descartes. In fact, the very word ‘consciousness,’ which we think of as inextricably connected to our concept of mind, did not exist in anything like the modern sense before the 17th century. Philosophers before Descartes did not have a ‘mind-body’ problem because they followed Aristotle, for whom the very fact of being a living entity meant you had mental qualities.

Descartes broke with the Aristotelian and medieval traditions by recognizing that living matter is just matter, thereby kicking off three centuries of scientific reductionism with all its impressive achievements and methodological pitfalls. But Descartes didn’t have the philosophical fortitude to go all the way: perhaps mindful of the fate of his contemporary, Galileo Galilei, he dared not include the mind in his treatment of the human body as a machine. In Descartes’ Treatise of Man we find intricate diagrams of how vision works, and he even suggested the very modern idea that memory is distributed throughout the brain. But he stopped short at cognitive and reckoning functions, which he took almost entirely out of the brain and confined to an immaterial soul. However, he immediately realized his dualism created one of the most powerful problems in philosophy of mind: if the mental and the physical are distinct, how do the two interact, as they obviously must in order for a human being to be functional?

Descartes’ solution was unsatisfactory even to him and recognized as troublesome by philosophers ever since. He located the seat of consciousness in the small pineal gland (which is not part of the brain) and conjectured that somehow that part of the endocrine system serves as the bridge between the two worlds he had created in his speculations. Empirical evidence immediately contradicted Descartes’ choice: people can function and have mental states without the pineal gland, which turns out to regulate the production of melatonin. But the main problem was philosophical: just saying that ‘somehow’ the gland (or any other physical structure) provides for the interaction between the mental and the physical quite obviously solves nothing.

The history of philosophy of mind after Descartes has been marked by a gradual but steady repudiation of dualism, which has taken full form only during the second half of the 20th century and is still being elaborated along the directions provided by several schools of thought. The first blow was dealt by skeptic philosopher David Hume in the 18th century. Hume was still a dualist, and defended that position on the basis of what is known as the properties argument: mental phenomena lack spatial extension and position, hence they must be non-material. But what is this non-material mind? Hume famously rejected any idea of a spiritual substance (à la Descartes) affirming that introspection does not lead us to discover anything but our own perceptions: “I never can catch myself at any time without a perception, and never can observe anything but the perception”, which led him to formulate his concept of mental activity as a ‘bundle’ of perceptions. Hume dissolved Descartes’ unitary conception of the mind into a set of ‘things’, but had not solved the problem of how these immaterial objects can possibly interact with the body.

The next step was taken by Thomas Huxley (1825-95), often known as ‘Darwin’s bulldog’ for his fierce defense of evolutionary ideas. Huxley was convinced that the empirical evidence strongly suggested that Descartes was right in treating animals as machines (which had evolved by natural selection), but – probably also because of his evolutionary ideas – he could not conceive that animals are so different from us. This brought him to the verge of rejecting dualism, since only two roads are open: either animals have mental states too (though to a lesser degree than humans), or else we are all automata, including Homo Sapiens. Huxley managed to strike a desperate compromise: both we and animals do indeed have consciousness, but this is completely powerless, because it is an epiphenomenon of the brain’s activity. As he put it: “[the phenomena of the senses] are something manufactured by the mechanism of the body and as unlike the causes which set that mechanism in motion as the sound of a watch that strikes is unlike the pushing of the spring which gives rise to it.” This is a beautifully poetical notion of the mental as the ethereal epiphenomenon of very physical materials and actions. The main problem, of course, is that Huxley couldn’t account for how mental phenomena can have obvious effects on the physical realm of which they were allegedly a powerless byproduct.

Enter the modern era of philosophizing about the mind, with the first notable contribution being delivered by Gilbert Ryle. In 1949 he published a highly influential book called The Concept of Mind in which he definitely rejected Descartes’ approach. Ryle’s response to the mind-body problem was to think of it as a category mistake, which he elegantly captures with an analogy. Imagine a tourist visiting Oxford who, upon seeing the colleges, libraries, laboratories, teachers and students, asks: “OK, but where is the University?” Analogously, for Ryle mental activity is not a different thing from physical activity – it is comprised by the latter. While this may work for a university, when translated to the mind it amounts to denying the existence of internal mental events that are not observable. This sounds suspiciously like behaviorism, which was all the rage in psychology at that time, though Ryle denied it. As with the behaviorists, Ryle’s approach is unsatisfactory precisely when it comes to what most of us consider the all-important aspects of the mental: in bypassing the internal mechanisms causing the observable behaviors, we have eliminated most of what’s interesting about the problem of mind.

The 1950s saw a multi-author attempt at a fresh start with the mind-body problem. That new approach is now known as the ‘identity’ theory. H. Feigl, U.T. Place and J.J.C. Smart, among others, attempted to go beyond behavioristic physicalism and once and for all identify the mind with the brain. But, these authors maintained, the trick is in which particular meaning of the word ‘is’ one is using while saying that the mind is the brain. In English, we can use ‘is’ in three different forms: as a predication, or attribution of characteristics (as in “a lion is a carnivore”); in a definition, or stating a logical necessity (“a triangle is a geometric figure with three sides”); and in a composition, or stating of a contingent necessity (“lightning is a discharge of electricity”). Clearly, the sentence “the mind is the brain” is of the third kind and amounts to saying that mental states are identical with particular states of the brain (not because they logically have to be, but because it so happens in this corner of the universe). The problem here, besides the obvious empirical question of exactly how this identity works, is that there are instances in which a simple identity seems rather unsatisfactory. For example, is the relationship between brain states and mental states a simple one-to-one mapping, so that everybody that thinks that tomorrow is Monday is in the same brain state? This seems hardly reasonable and contradicts what we know of brain plasticity and more in general of the way the brain works, which raises serious problems for any theory of strict identity.

Skipping fashionably extreme positions (such as Patricia and Paul Churchland’s idea that mental phenomena such as emotions and sensations simply do not exist and we should change our common language to talk only about neuronal activity – a school known as eliminativism), we have arrived at the current orthodoxy in philosophy of mind, functionalism. Jerry Fodor has been a leading force behind this school since the late 1960s. He rejects the simple reductionist approach of the identity theorists, suggesting that a better way to think of the mind-body relation is that mental phenomena represent functions that can be performed by different types of physical structures. In a sense, the mental is the software, and it can be run on different sorts of hardware.

Let us consider the difference between the identity theory and the functionalist approach in more detail. We have seen that for an identity theorist the ‘is’ connecting mind and body is analogous to the one in the phrase “lightning is an electrical discharge”. The latter is true, and lightning can only be electrical discharge (in this universe). Consider now the phrase “genes are carriers of information”. This is not a type-type identity (as the lightning = electrical discharge is), but what is known as a token-token identity, because there are different ways in which genes as carriers of information can be instantiated in actual living organisms (e.g. while most species use DNA, some use a similar but distinct nucleic acid, RNA. Furthermore, special computer programs known as genetic algorithms have ‘genes’ that are not made of either DNA or RNA). Similarly, functionalism allows the possibility that mind could emerge from matter other than a brain.

All of the above theories have left plenty of unsatisfied philosophers who delight in pointing out real or imaginary problems. For example, John Searle’s criticism of simplistic “mind = brain” equations is based on a thought experiment about somebody sitting in a room who receives, through a slot in the wall, cards with Chinese characters written on them. He looks them up in a big book of rules and accordingly pushes other cards out through the slot. To an outside observer it seems like the room is answering a series of questions in Chinese, but to say that the room understands Chinese goes against all our intuitions. Fred Jackson has also produced a thought experiment, this one about an imaginary scientist called Mary who grows up in a room filled only by black, white and grey objects. She is taught everything about the theory of color, but when she steps outside of her enclosure and actually sees a colored object for the first time, our intuition is that she learns something utterly new, for which she is not prepared. While they may be instructive or provocative, thought experiments of this type are based on the questionable assumption that our intuitions about highly unfamiliar situations are reliable. When faced with these speculative scenarios our intuitions may simply be worthless, or at most point us only to the philosophically less interesting problem of the biases that we have as human beings when thinking about the mental.

All of this notwithstanding, where is philosophy of mind at the turn of the 21st century? It seems to me that it is becoming more and more entwined with neurobiology and evolutionary theory, perhaps confirming once again that the role of philosophy is to mull over problems while they are empirically insoluble and then clear the way for a scientific approach to the problem if the latter becomes possible. Be that as it may, the current excitement in this field comes from philosophers who are open to the findings of biologists and from those biologists who are willing to embrace the big picture offered by philosophy and go beyond the specific results of their daily experiments.

Perhaps the most promising areas of research in the borderland between science and philosophy of mind are experiments with brain-damaged patients, with neuroimaging of the brain while carrying out a variety of mental tasks and with the computer simulation of elementary brain processes by way of neural networks. Studies of individuals damaged in parts of their brains have revealed how specific physical structures are directly involved with fundamental mental experiences: the amygdalas and hypothalamus are essential so that we can feel emotions and use the emotional content of an experience as a guide to what’s important or not in our lives. Subjects with severe impairments of these structures, far from being perfect rational beings capable of Kantian ideals (or, to be more prosaic, beings like Spock or Data on Star Trek), rather remind us of Hume’s famous contention that emotion is fundamental to our motivation because without it we wouldn’t be able to distinguish between the importance of the destruction of the world and that of scratching a finger. These findings, as well as more general theories proposed by neurobiologists such as Michael Gazzaniga, V.S. Ramachandran and Antonio Damasio, at least force the philosopher to agree to a ‘non-ectoplasm’ clause for the mind-body relationship: while the relationship itself may still be unclear, if the brain goes, then the mind ceases to exist (with all the metaphysical and theological consequences one can easily imagine).

Neuroimaging is developing to the point of allowing us to map in detail the brain activity corresponding to, for example, reading, moral decision making and even praying and meditating. Again, the emerging picture is that distinct kinds of neurons and brain areas carry out different tasks, rejecting once and for all the idea of the brain as a general purpose computer. Rather, the mind seems to be made of diffuse and complex modules, some clearly shaped by natural selection to carry out fundamental tasks such as identifying objects by their color. (Is our ability to perceive secondary qualities a result of our ancestors’ need to distinguish between food and foes in the jungles of the Jurassic?).

Finally, the simulation of relatively sophisticated brain functions such as categorization, identification of objects, and memory by distributed networks of neuron-like elements is providing a potentially very valuable alternative to old fashioned artificial intelligence while in the process raising a whole array of problems of its own (e.g. we can simulate category formation within a self-improving neural net, but then have serious problems understanding how actually the net itself works!).

Any philosophical theory of the mind has to come to terms with the ever-increasing wealth of empirical information which is slowly moving the study of the mental out of the fog of its first three centuries and into some as yet dimly perceivable light. I still don’t know exactly what it means for me to have had ‘in mind’ to write this article, but both scientists and philosophers have a fresh new century to look forward to for some progress in this ultimate quest for selfunderstanding.

Massimo Pigliucci is Associate Professor of Ecology & Evolutionary Biology at the University of Tennessee. In his spare time, he is a graduate student in philosophy at the same University. His ramblings can be found at www.rationallyspeaking.org.

Additional readings

A much more in-depth analysis of the history and current status of philosophy of mind can be found in the provocative The Mind-Body Problem: An Opinionated Introduction, by D.M. Armstrong (Westview Press, 1999).

A fundamental antidote to much nonsense in philosophy of mind can be taken by reading J. Searle’ ‘What’s wrong with the philosophy of mind’, in his The Rediscovery of the Mind (MIT Press, 1992).

For a stimulating connection between the broad philosophical view and the detailed empiricism of neurobiology, see Antonio Damasio’s The Feeling of What Happens: Body and Emotion in the Making of Consciousness (Harcourt Brace & Co., 1999).