© Springer International Publishing Switzerland 2015
Pascual Ángel Gargiulo and Humberto Luis Mesones Arroyo (eds.)Psychiatry and Neuroscience Update10.1007/978-3-319-17103-6_33. Trends in Philosophy of Mind and in Philosophy of Neuroscience
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School of Philosophy, Pontifical University of the Holy Cross, Via dei Farnesi 83, 00186 Rome, Italy
Introduction
Philosophical questions regarding the nature of the mind and its relationship with the body are usually addressed by philosophy of the mind. This area of philosophy inherits the traditional issue of the relationship between the soul and the body, interpreted in modern terms as the mind and the brain. Whereas the classical view of the problem was thoroughly ontological, going back to ancient philosophers as Plato and Aristotle, philosophy of mind, born in the twentieth century, is generally more epistemological, posing its object of inquiry within a scientific framework. Its topics are similar to those treated by the cognitive sciences such as neurobiology, computational science, and cognitive psychology.
These topics, namely perception, sensations, emotions, memory, language, thought, and free will were typically considered to be psychological. Scholars in this area of science also face questions regarding the nature of the mind and the meaning of the human person, who is seemingly made up of of mental capacities and neural processes, two dimensions related to the classical duality of the soul and body.
The novelty of philosophy of the mind, compared with classical psychology, is that the problem is tackled in strong relationship with the natural sciences. In dealing with psychological notions such as thought, intelligence, decisions, and representations, two areas are neuroscience and computational science. Neuroscience studies and explains all that was typically reserved to psychology from an empirical perspective. Computational science seems capable of reproducing and dominating representations and thought processes. Accordingly, it seems natural that philosophy of mind will turn out to be a kind of philosophy of neuroscience and a philosophy of computation, although essentially more the former, if we take into account the recent development and prestige of neurobiology regarding human problems. This is clearly demonstrated by the proliferation of “neuro-disciplines” such as neurophilosophy, neuroethics, neurotheology, neuroeconomics, neuroaesthetics, etc.
The difficulty with the resulting discipline is that it does not share the capability of the older metaphysical psychology in acknowledging a spiritual dimension to the human person. As human thought appeared to be immaterial or non-physical, psychology classically maintained a good relationship with theology. To think of God as an immaterial Being and then to speculate on the immortality of the human soul beyond the destruction of the human body was natural for many authors. However, in contemporary philosophy of mind, these issues appear more problematic because ontological concepts, such as being, form, and essence, are not available in the general scientific environment, whereas scientific concepts dealing with physical, chemical, and biological concepts are familiar to scholars. Subsequent to the Kantian revolution, metaphysics was viewed with suspicion by philosophers and scientists, while the natural sciences became more consolidated and capable of vindicating the privilege of truth. Consequently, classical philosophical problems needed to be investigated in dialogue with the natural sciences, and sometimes in subordination to them. This is the current epistemological condition of philosophy of mind and philosophy of neuroscience [1].
According to this scenario, the first and perhaps most important problem of philosophy of mind and neuroscience is the alleged distinction between mental and neural acts or events, while the second problem, provided the distinction is accepted, is their causal mutual relationship. These two main philosophical questions are answered differently by a series of standard positions: dualism, neural monism, functionalism, emergentism, and non-reductive physicalism.
In this chapter I attempt to briefly present these positions, and to combine them with what can be understood as the philosophical thought of authors dealing with neuroscience rather than with a pure philosophical speculation. Many other problems, such as the relationship between neurobiology and philosophy, the extent of human freedom, the assessment of human actions in ethical issues, the particular orientation given to psychiatry, or the focus of educational efforts, depend essentially on the solution given to these fundamental questions.
Standard Positions in Philosophy of Mind
Philosophers of mind normally display an array of similar positions regarding the mind-brain duality. These different views can be found in any textbook on philosophy of mind [2–4]. My presentation attempts to go to the root of the problems and to indicate what I consider most relevant for the purpose of this book. My account is clearly favorable to some type of moderate dualism. I do not attempt to suggest being neutral on this issue.
Dualism [5]
Dualism claims that the human person is constituted through two kinds of realities: the first, material and the second, spiritual. In substantial dualism, the spiritual reality, known as the soul, spirit, or the mind, moves and guides the body, but it can also be affected by the latter. There is also the possibility of interaction between the soul and the body. Such a duality is attributed by Aristotle to animals and even to plants.
If the body and the soul are not understood as substances, they can at least be viewed in terms of properties, as is elaborated in property dualism. This type of dualism takes into consideration a group of human actions, processes, and operations as material because they are empirically verifiable, whereas others, such as thoughts, intentions, and desires are categorized as immaterial because they are experienced as qualia, completely deprived of material properties. With similarities to the assertion of substantial dualism, property dualism claims that spiritual operations move or guide bodily processes: a human agent as such, he or she, wants to move the hand, and thus moves it.
Dualism can be perceived either phenomenologically or through common sense. It is very intuitive to experience our thoughts, feelings, and decisions as something radically different from spatial material objects. Dualism can also be sustained through religious beliefs, and indeed, religion would be devoid of sense if all that exists were purely material. Materialism and atheism are intrinsically linked [6]. Finally, dualism can be argued and explained in philosophical terms.
In spite of the various philosophical accounts of the soul-body or mind-brain duality, dualism is a strong and persistent conviction held by many people because it corresponds to direct knowledge, or to what could be nominated as the common sense perspective. Even the most rigorous materialists cannot avoid experiencing thoughts and consciousness. The efforts made to reduce all reality to material reality are normally very complicated. They must be argued over and over, struggling against what constantly reappears in common language and implicit belief (i.e., consider the paradox of saying: “I think that this I does not exist”).
Naturalism or Physicalism
According to this position, nothing other than material substances or material properties exist. The apparent existence of mental acts must be reduced to something material, and this is why naturalism, or materialism, is often reductionist because it is committed to the effort of reducing an alleged entity to something different. Reductionism is also shared by what will later be termed “neurologist monism”. The attempt to eliminate the notion that is reduced corresponds to the so-called eliminativism [7] advocated by Paul and Patricia Churchland [8, 9].
A reduction aims to be an explanation [10]. Thus, materialists typically argue that a thought is nothing but a neural circuit and the circuit explains the presentation of a thought. This epistemological procedure is taken from physics. For example, the phenomenical presentation of light can be reduced/explained through electromagnetic waves. The reduction is correct, but the phenomenal light—the light as we see it—still remains a psychological or a mental fact.
Notwithstanding the efforts to reduce the psychological process of vision to neurophysiological events, the phenomenon is not eliminated, therefore the duality between psychological and physical events persists. This is the paradox of physicalism, in its concern with reducing and eliminating the existence of mental properties.
Naturalism or physicalism [11] has its roots in the prestige of physical explanations. The reason that sustains the widespread materialistic belief is mainly epistemological. Physics deals with spatio-temporal objects, ultimately testable by empirical procedures which are based on what can be detected by external senses or by public instruments of observation. Therefore, nonobservable entities as such will never exist although they could be postulated as instrumental logical devices (i.e., physical laws or mathematical spaces) capable of explaining physical phenomena.
The physical universe of discourse—the world as is viewed by physics—is understood as closed or exclusive. Nothing can be postulated outside of this framework. God, the angels, souls, and mental entities are rejected because they do not fit into the ontological framework of natural science. Of course, it can be said that the world as it is seen through physics is an abstraction because it is the result of selecting a series of basic properties (mass, space, movement, time, force) as a methodological choice for the explanation of all phenomena. In this sense, natural science is a partial view of reality and does not comprehend reality as a whole [12].
Paradoxically, even sensations, the so-called qualia in philosophy of mind, are problematic for materialism. Psychological acts and states do not belong to the realm of physical and observable events [13]. Accordingly, psychic events, such as acts of vision, pain as a sensation, and so on, should be ruled out by being reduced to neurophysiological events that can be detected by our external senses or by instruments of observation.
For instance, the sheer sensation of pain cannot be externally observed. Pain, no doubt, is quite physical, but as such it does not belong to the universe of discourse of physics. If this universe is taken as exclusive, then pain becomes problematic and must be reduced, and as a psychological act it will be understood as nothing. Hard materialist philosophers view the psychological world with suspicion because they rightly feel that to accept that world could lead to the acknowledgment of something beyond matter. They opt to protect the choice of remaining within the closed natural scientific world.
Now, how can reduction be accomplished? On one hand, there is the notion that is supposed to be reduced, which in this case is the psychological reality: perception, representation, emotion, comprehension, or the self. On the other hand, some physical features (some functions of the human body) must be chosen as the matter to which the psychological events are supposed to be reduced. Three candidates are available for this effort: external actions and reactions, neurobiological processes, and computational procedures, giving us three possible positions.
Behaviorism
Internal actions are behaviorism’s preferred object of reduction. Internal operations or states, such as emotions, decisions, and perceptions, always have some relation to external actions, or at least they can be ascertained through external reports and tests, therefore, it is not difficult to attempt to assimilate the former within the latter. Accurate analyses, however, demonstrate that these two different types of acts are not equivalent.
Philosophical behaviorism [14], although not always known by this name, aims to translate internal acts into behavioral dispositions. Psychological behaviorism, however, follows the scheme of stimulus/response, and the associated notions of reinforcement and reward. In both cases, dualism should to be avoided. As is well-known, psychological behaviorism was eclipsed by cognitive psychology; but even so, this psychological school was helpful because it demonstrated the importance of paying attention to behavior when attempting to study and to follow psychological states.
Neurologist Monism
The reduction of mental acts to neurobiological processes might seem a more promising proposal. Perceptions, sensations, feelings, and conscious or unconscious cognitive states normally show a clear neural basis. The acts of vision, touching, smelling, and others associated with the senses can be described and explained in neurological terms. It can at least be claimed that mental acts always have some correlative type of neural acts or states. This type of correlation is often considered as falling under the category of supervenience [15]. The correlation between both dimensions must be defined in very precise terms, which is not an easy matter.
Neurologist monism (this denomination is mine) claims that a psychological act is nothing more than a neurobiological event. There is no a special term for this trend of thought in philosophy of mind, which at other times was known as the identity theory. This position seems to be similar to something that I had previously called naturalism and can be seen as the most frequent version of naturalism in our times. Although many authors take for granted that this is the correct solution to the problem, the difficulties of this position have already been highlighted above. There is no doubt that the neurological dimension of psychological acts is essential, but it can also be demonstrated that it is partial. To perceive or to be conscious, is not exactly the same as a purely neural event.
Computational Functionalism
The third attempted reduction springs from computational science and could be indicated as computational functionalism [16]. This position apparently goes beyond reductionism as understood in neurologist monism and behaviorism. It seems to recognize a certain immaterial content inside the alleged black box of the internal acts. Functionalism in philosophy of mind is, in general terms, a sophisticated position that equates mental states with causal roles or functions [17]. The supporters of this position do not accept the simple experience of feeling as a decisive feature of mental acts. Pain, for instance, should rather be defined functionally. This approach is not necessarily incompatible with the acknowledgement of qualia as real internal experiences. The reductionist move now appears clearly in computational functionalism. Mental acts could be identified with computational functions or with information processing.
The key word here is information, which has several meanings connected with the transmission of messages and causal effects. Generically, information implies order in nature, an order introduced within an energetic physical basis. Order is a functional notion related to a certain goal to be attained through a particular arrangement of elements in space and time. Living organisms have the capacity of controlling information, received from the environment and transmitted to the different parts of the body in order to maintain the typical self-organization that characterizes the living system. When this information control is associated with cognitive representations (i.e., perception), then the living system, endowed with a nervous system for that purpose, is called an intentional or a cognitive organism. This is the case of animals and humans. However, it is possible to separate the flow of information from its natural basis and to treat it using an artificial device (a computer). This procedure is a calculation, namely a transformation, according to an algorithm, of some inputs into certain outcomes.
It is tempting to say, then, that psychological operations or states should be just computations. At this point inputs can be connected with outputs in a certain system through different computational procedures, as is typically done by a computer. Computational devices are able to capture informational processes occurring in the physical world, particularly in organisms and brains, and to freely manipulate them so as to simulate and emulate natural or intentional processes such as biological processes, diseases, perceptions, problem-solving, and decision-making techniques. The task of the brain would be similar to the operations of a computer.
Computational functionalism was strongly stimulated by the development of artificial intelligence and robotics. But a new sort of dualism, namely between software and hardware, has now appeared, especially because the software, corresponding to the mind, is multiply realizable in different physical media (e.g., a brain, a standard computer, a quantum computer, etc.). Therefore, the computational mind appears to be independent from its bodily realization.
The problem with functionalism is that it concedes too little importance to the neurobiological basis of psychological states. It is easy to produce pieces of information manifoldly, just as a book can be printed or registered in any kind of computer. But this is not the case in a real cognitive operation or in an emotional state. Two people can share the same thought, such as 2 + 2 = 4, but nevertheless, each one of them has a personal thought.
This is the reason why neurobiologists normally pay little attention to computational functionalists. Engineers and computer scientists, instead, are more attracted by the functionalist proposal. The computational theory of mind favors the idea of a possible introduction of consciousness into a computational machine. But what kind of consciousness would a robotic consciousness be? It would be an imitation, not a real psychological state. Functionalism takes one aspect of mental states, the informational one, and ignores those states of lively action performed by real people. In this sense, functionalism is a new form of reductionism.
Emergentism and Antireductionism
The recognition of irreducibly higher levels in a stratified natural universe—life over non-life, sensitive consciousness over life, and human reason over sensitive consciousness—in the twentieth century produced the anti-reductionistic position called emergentism. This position emphasizes the existence of new kinds of properties emerging from the construction of lower layers, provided that they are organized in a certain way [18]. Namely, mental states naturally emerge from a precise organization of neural integrated circuits.
There can be strong or weak versions of emergentism. The strong versions are not far from a moderate dualism, such as that found by Popper [19]. The weak versions (Bunge) [20] interpret the emergent properties as new global structures constituted by the assembly of many parts. The whole is more than the sum of the parts, as a house is more than a pile of bricks. John Searle [21] follows an intermediate position.
One of the problems faced by emergentism is the difficulty of providing an account of the causality between mental and neural events. Clearly the neural basis enables the subsistence of psychological states, and when this basis fails to function, impairment and disorders follow (bottom-up causation). However, it seems that insights and decisions, for instance, the ideas flowing through my mind that cause me to write these lines, also spontaneously select many brain activations in very specific areas (downward causation). Musical performance and linguistic abilities are responsible for specific brain activations and shape cerebral patterns in several ways. Emergentists usually stress downward causation while attempting to avoid interactionism in a dualistic sense. They criticize all types of reductionism, whether neurologist or functionalist.
Connections that give rise to correct sounds or utterances are reinforced during the learning process, while those that produce the wrong results are not; and the difference is determined by the semantic rules that govern the systems. In this sense, certain connections within the brain, as well as with nerves and muscles, are selected and shaped through a process of downward causation: from the contents and meanings of the musical and linguistic signs, according to the semantic rules of musical notation and ordinary language, to neural and neurophysiological connections. To this extent, content and meaning, which, as externalism has it, go beyond the individual’s brain and bear an objectivity of their own, are causally responsible for the actual shaping of the neural connections and networks required for a competent musical or linguistic performance [22] p. 197–198.
Neurophilosophical Proposals
In addition to the official philosophers of mind, neuroscientists who are sensitive to humanistic topics frequently present opinions on epistemological and anthropological items regarding the problem of mind and brain, the nature of knowledge, human identity and free will, and other themes that justly correspond to the philosophical domain, even in ethics and religion. Their observations on these topics are sometimes episodic or very brief and are frequently found in popular books. However, in other cases, they can be more systematic, ambitiously delineating a complete view of man. Their reflections can be located on the frontier between science and philosophy. They convey an amount of useful information regarding neuroscientific achievements and usually enter the philosophical field without the sophistication of professional philosophers. Hence, they risk being naïve in subtle matters or unduly mixing what can be scientifically demonstrated with what needs careful philosophical argumentation. In spite of these difficulties, the contribution of these authors to the philosophy of neuroscience is undeniable and can be considered complementary to the philosophers’ efforts in the corresponding areas.
It is not easy to identify clear-cut positions among the authors involved in these neurophilosophical writings. Some of them more directly engage the current problems in philosophy of science and propose a solution. The solution can be dualistic, as in the case of Eccles, which is currently rather exceptional, or it can be materialistic. A number of them share a less than well-defined naturalistic background. While they usually reject a drastic dualism, being open to some form of imprecise non-reductionism, they contemporaneously include neurophysiological items that can enrich the anthropological view. Two other related areas of research are neuroethics and the so-called neurotheology. The former studies not only the problem of the legitimacy of deep neural interventionism human beings, with their consequences for personality and society, particularly in the areas of health, education, marketing, and culture, but also the biological foundations of ethical inclinations and actions. Neurotheology is concerned with the correlations between religious experiences and brain activations. Depending on their philosophical position, namely either materialistic or perhaps open to the spiritual dimension of man, researchers involved in these areas sometimes draw contrasting conclusions regarding the distinction and causality between mind and brain.
Without any attempt at classification, this section sketches out in broad lines those authors and insights that can be viewed as paradigmatic of these positions and as an expression of the major concerns and attitudes on the topics considered in this chapter.
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