Dualism and Mind | Internet Encyclopedia of Philosophy
In this sort of dualism, mind and body are conceptually distinct, though the The primary source for Plato's views on the metaphysical status of the soul is the .. into the nature of the relationship between mental and physical properties. The mind-body problem is the problem: what is the relationship . Plato's dualism is not, therefore, simply a doctrine in the philosophy of mind. Dual Theories of interpreting the Mind-Body Relationship. tradition stemming form Plato to Augustine and to Descartes —an apparently safe and simple way to .
This, however, could not hold for the physical-mathematical explanation of inertial type, which Descartes proposed in his physiology for the action of corporeal spirits. The idea that the spiritual soul would shift the direction of motion of a flow of "spirits" in the pineal gland epiphysis of the brain, in such a way to set off a "voluntary" movement of the human body, was against a fundamental principle of conservation in mechanics, directly derived from that of inertia, known as the "principle of conservation of momentum.
In any case, moving beyond any specific criticism to the Cartesian mechanism, every dualist-interactionist theory between spiritual minds and material bodies implies a violation of some kind of principle of energy conservation.
In this way, such a criticism completes from a modern scientific point of view the criticism that in the Middle Ages St. Thomas had already made against Platonic interactionism in metaphysical and theological terms. As a matter of fact, while criticizing Platonic dualism, Thomas Aquinas affirmed that if the spiritual soul is in a causal relationship with the body through the influence on the action of the corporeal spirits, then the principle of the substantial unity of the person is lost, and it becomes difficult to explain the individuality of the soul, which according to Plato can reincarnate in different bodies, a hypothesis which is considered absurd by Christian theology cf.
Thomas Aquinas, Summa TheologiaeI, q. The most fundamental contribution that John Eccles made was the attempt to provide a new solution to the physical-mathematical problem of the violation of the conservation principles that emerges in all interactionist approaches; like many other modern authors, he was convinced that the only way to support the right ethical and religious reasons for the existence of a spiritual soul was to adhere to a dualist-interactionist metaphysical vision of a Platonic-Cartesian type cf.
Eccles and Popper, ; Eccles and Robinson, Eccles believed to have found such a solution through the reference to the principles of quantum mechanicsnecessarily involved in the chemical-electrical mechanism of synapse communication. In fact, according to the principle of indetermination, we could think of an extra-physical action exerted by the mind on the synapses of the various cortical neuronal populations, without the violation of any principle of energy conservation.
There are two main objections that can be moved towards this solution, one of a biological type, and the other, more substantial, of a physical type, they both having immediate metaphysical implications.
Generally speaking, most biologists agree in saying that the characteristic physical level where the vital phenomena emerge in their irreducible specificity is that of the macroscopic scale, where the organization and possibly the self-organization of complex molecular structures proteins occur, which are stable out of the thermodynamic equilibrium. They are "dissipative structures" that self-organize and continually exchange matter-energy with the external environment, internally and externally to the body cf.
Prigogine, From Being to Becoming. Stengers, Order Out of Chaos. Man's new Dialogue with NatureLondon ; I. An Introduction, New York Yet, here we are faced with an important metaphysical consequence. If we accept that the biological and - in our case-the neurophysiological level is that of the microscopic quantum scale, given that such a level and its related uncertainty are universal for all the material structures of organic and non-organic nature, why then not brush up again the Gnostic and Neo-Platonic theories of the anima mundi type?
Then, why would not all matter be animated? His objection is that it is unfounded to endorse the suspension of the causal physical determinism on the account of the quantum uncertainty. The quantum phenomena only show uncertainty when faced with the problem of "reduction of wave function" and to the problem of the amplified "reading" of quantum event, on a macroscopic scale, in terms of the mathematical formalism of classical mechanics that is, in terms of the functions that define one-dimensional trajectories; cf.
On the other hand, the description of quantum phenomena in the microscopic terms of the appropriate mathematical formalism of the wave function is supported by experimental measures which agree with the theoretical predictions, and show no uncertainty at all, despite the temporary state of quantum electrodynamics which provides such predictions cf.
Therefore, it is not at the quantum level that we can hope to solve the scientific groundlessness found by modern authors in the dualist interactionist explanation. Theories of a Monistic View Theories of a monistic view are "metaphysically reductionist," and they still are even at present time, when they are forced to be "epistemologically non-reductionist" by logical evidence see aboveI.
These are metaphysically reductionist since they reduce one of the two terms to the "product" of a function or many functions of the other. The history of philosophy of the second millennium brings to us two distinct types of monistic theories, spiritualist and materialist. This philosophy of nature considers the material particle in terms of an "non-extensive singularity," hence immaterial, of a "monad," in such a way that each physical body results as an aggregate of immaterial monads, all which are in the end "internal" representations of the Absolute Monad.
This theory, that was judged by Hegel as a "metaphysical novel," for us it is merely of academic interest. Here we shall dedicate more attention to the theories of materialist nature. The materialistic monism consists in the reduction of human psychical life to the product of the neurophysiological functions of the body, considered a sort of "secretion" of the neurons. As main representatives of this anthropological teaching we can consider all the major empiricist philosophers of the Modern Age, from Hume to the contemporary positivists and neo-positivists.
In the 20th century, this way of proceeding is presented in different versions. A first version is that of the "theories of identity," already presented in Section I and which we do not need to recall again. A second version is represented by the "emergentist theories. The term "emergence" is to be understood at a level of organization of matter that, maintaining the validity of the laws at the lower level, needs for its scientific characterisation the formulation of new laws.
For example, it is evident that the laws of thermodynamics apply to all chemical systems, however it is not possible to simply derive from the laws of thermodynamics all of the chemical properties of the molecular compounds, although it is clear that in both cases the referent is always the same aggregate of molecules.
With the same type of reasoning the theory attempts to explain the emergence of the psychological facts and their laws as the emergence of a new, higher level of organization of the same physical substratum. Here, we are not far from a theory of identity: The limits of the identity theories already discussed, are the same as those of the emergentist theories. A third version of materialistic monism is represented by the "behaviorist theories. Watsonand considered each reference to the 18th century psychology of conscience as non-scientific, in particular that of phenomenological nature.
Then the behaviorist theory acquired philosophic dignity in the 's, thanks to a fundamental work by Gilbert RyleThe Concept of Mind The leading idea of this theory is the non-objectivable character of the conscious "self", intended as the "presence to my self" what I am able to render as an object to myself is only "me," however always relatively to its past states or acts and its systematic elusivity, like the present temporal moment, the "now," the nunc. From that it derives its criticism to the "Cartesian self", intended in an objectivistic way as a "spiritual thing," and the proposal of a "dispositional behaviourism" as the characteristic object of a really scientific psychology.
In other words, because of the systematic elusivity of the temporal moment, what is objectivable of behaviour is not the physiological event as such for ex. This approach has resulted particularly prolific in scientific terms because it created on a theoretical scale a link between the old type of behaviourism belonging to the associationistic psychology of Pavlov and Watson and the computational approach typical of functionalism, and this because the notion of a "disposition to act" correspond immediately to the matrix calculus of statistical mechanics applied to the study of the cerebral dynamics.
In fact, a status that shows disposition to act can find its immediate operational equivalent in a matrix of transition probabilities, which is, in statistical mechanics, a classic algebraic instrument of calculus. Such a matrix of n 8 n elements, for each time tkdefines for each element the probability of transition from one to any other of its possible states for ex. On a formal scale the "neural networks" are nothing more than very evolved, and sometimes very complex, versions of this basic idea.
At the beginning of the 's Hilary Putnam born inwith his famous work Minds and Machineslaunched the research program of "functionalism," having the intention to solve the mind-body problem in terms of the software-hardware relationship of a computer. Such an approach, which is today completely repudiated by its initiator, had the intention to re-propose on a new basis the classical rationalist theory of the mind. Putnam did so in the light of the notion of "cognitive unconscious" taken from the psychology of intelligence elaborated by the Swiss psychologist Jean Piagetwho identified the intelligence with the development of logical-formal operational schemes and their unconscious use by the subject cf.
Piaget, Logic and Psychology, ; J. Putnam's second pillar was the development of a theory of computability starting from the mathematical interpretation of formal logic and the notion of propositional function operated by Gottlob Fregewhich had experienced two futher steps.
Therefore, the UTM constitutes the logical scheme of a modern multi-programmable calculator. The link with the field of behaviourism was derived by a further demonstration obtained by W. Pitt inthat guaranteed the equivalence between the algebraic matrix calculation of a simply interconnected network of neurons and the calculations which were executable by a TM.
From here followed, in the 's, the development of the two main features of functionalism, that ultimately led to the so-called "strong version" of the research programme of Artificial Intelligence AI: It appears therefore totally insufficient in accounting for the intentionality and the intensional logic referring to the "contents" cf. For this reason, in the functionalist approach of "strong" AI, it is necessary to rely on an "oracle", according to the expression coined by Turing himself, a figure of unquestionable universal intelligence that is able to produce its responses of truth and coherence without conceding any possible control on its action.
Hofstadter comes to this conclusion and ascribes in a neo-Spinozian way the metalogic function of "universal intelligence," of "oracle," to the non-computable determinism of the matter as a whole, matter of which also the brain of a single individual is part of, a determinism that appears "inviolable" towards the necessarily partial self-referentiality of the cerebral computations of a single brain.
In such a way, functionalism reveals its "double monist" nature for a theory of mind-body relationship. It is monist not only because it denies the "immaterial" dimension of intelligence, but also, and above all, because it denies the existence of "individual" intelligences which produce thoughts and are capable to act freely. That is, it denies the metaphysical foundations of the notion of person. From a metaphysical point of view, functionalism appears as a re-proposal of the rationalist theories of the mind that deny to the single individual the capacity to think "with his or her own head," as was proposed already in the Middle Ages by the theories of the Arabian rationalist aristotelism of Avicenna and Averroes, in the Modern Age by the theories of Spinoza and Hegel, and in the contemporary ages by the doctrine of Husserl and his meta-individual "phenomenologic Self.
On the other hand the approach of the cognitive sciences to the study of the mind and of the mind-body relationship can also be interpreted according to a "dual" type of metaphysical scheme, provided a renunciation of its original functionalist character.
However, before examining the dual theories, it is necessary to make a brief consideration about the intrinsic limitations of the functionalist approach, or theory of the "strong" AI, that leads its authors to the "oracle solution" and brings them to the above mentioned twofold monist outcome. It is clear that in the functionalist approach each human mind corresponds to a UTM, given the capacity the human mind has for a universal thought.
Now, the incapacity of a UTM "to have the knowledge of not knowing" depends upon the famous theorem of limitation which is intrinsic to the Universal Turing Machine computations. This machine has the capacity to simulate the calculations of all the single TM, in such a way to confer universality to their computations, but has the limitation of not being able to decide when its calculations have reached a satisfactory outcome and have to stop consequently.
In particular, the UTM cannot find a decisive computational procedure, through which "to assert" in its arithmetic meta-language that a certain datum expressed in its arithmetic language is "false. Human intelligence is capable of correcting itself, of progress and development, unlike animal intelligence, precisely because of its ability to notice its own errors. Basti and Perrone,pp. From a point of view that takes into account the history of logic, to overcome the mentioned limits of the formal calculus would mean, at the same time, overcoming the limits of the axiomatic method itself, as if it were the "only" method in modern logic, and to recover the richness of the pre-modern analytical method, characteristic of Platonic, Aristotelian and Scholastic logic: In a word, to perform these operations would mean to render scientific dignity to the "logic of discovery" against the modern absolutism of the "logic of proof" and of its axiomatic method cf.
Dual Theories of interpreting the Mind-Body Relationship When speaking of "dual" theories we mean all those theories of the mind-body relationship that: In such way the mind-body relationship is interpreted according to the Aristotelian "hylemorphic" metaphysical scheme of the form-matter relationship Gr. According to the version given by Scholastic anthropology, the spiritual soul is the form of matter, and "form" and "matter", substantially united, constitute the living human body, the only personal substance of a human being and of that "unique" human being, capable of vital vegetative operations metabolism, growth, reproductionand of sensory-motor and intellectual functions for a review on the principles of the Aristotelian-Thomistic biology, cf.
With respect to the monist and dualist theories, the "dual" theories have three main characteristics: These characteristics especially the third are strongly present in the medieval thought of Thomas Aquinas, who made the choice to re-evaluate the Aristotelian hylemorphic approach in anthropology -not without operating a profound revision of its metaphysical basis.
He noticed that, besides an intrinsic superior coherence, such an approach could grant a great consistency with the principles of Christian anthropology, more than that shown by the Platonic dualist approach, especially for what concerned the person, its irreducible individuality and its intrinsic psychophysical unity. Many contemporary authors who operate today in the field of cognitive sciences intend to refer to a dual-type, and not to a monist-type metaphysical paradigm, even though only a few of them, in the recent past, were clearly aware that such metaphysical paradigm was not compatible with the functionalist approach of the cognitive sciences cf.
The localization of the Mind. The mind or, in the Scholastic, Greek-Platonic terminology, the "soul" is indeed a non-material "thing," as Descartes would have liked, however it is not a "substance" that is complete in its being in the way it is stated by the dualist theories. It is the formal principle of unity of a stratified whole of material parts today we would say: It is rather a non-material or "formal" component of a substance made of material parts that experience constant modification.
Where the notion of "form" is understood according to the Aristotelian philosophy of nature, as a constantly adapting plastic whole of relationships of disposition of dynamic material parts, continually modifying and interacting among themselves and with the external world. An example of it, is given, at the cellular level, by the metabolic physical-chemical activity of the cell itself. In this context the "mind," according to the dual theories, has a unique location with respect to the body, which the mind itself organizes.
Instead of being located "in the body" and at the most "in the head", as in all of the dualist theories Plato assigned its location to the attachment point of the neural cord with the cerebellum, Descartes in the "pineal gland" epiphysisEccles in the synapses of the populations of neurons in the cerebral cortexand in the ancient and modern monist theories, an illustrative solution that M.
Schlick defined "principle of introjection", the dual theories rather affirm that "it is the mind that contains the body. In a book which is strongly and justly critical towards the functionalist approach to the cognitive sciences, Penrose expresses himself on the matter: It is not all unreasonable to suppose that the persistence of the 'self' might have more to do with the preservation of patterns than of actual material particles" Penrose,pp.
Here is instead what was stated on the same argument by Donald M. MacKayone of the founders of the non-functionalistic approach to the cognitive sciences, to whom, amongst other things, we must acknowledge the definition of "dual theories" applied to this particular type of theories of the mind: Mental activity would be meaningfully locatable in principle in specific flow-structures of the information-diagram; but this meant that the relevant flow-lines would in general extend beyond the confines of any one component structure, and during conscious action might even run out-and-back through the environment.
Mentality, as a system-property, could be rendered invisible or destroyed by attempts to localize its action to any subsystem of the total information-flow pattern in which it was currently embodied" MacKay,p.
More recently, the same idea that the mind is embodied within the informational flow schemes, internal and external to the body, received support from A. It stands as the new post-functionalist paradigm in the cognitive sciences, one that tries to unite different elements, albeit not without some confusion. Regarding the localization of the mind or of the "rational soul" of the human being with respect to its body, in the Middle Ages, Thomas Aquinas held a position that was very similar to that of the modern supporters of the dual theory.
He said precisely that non-material entities, such as the soul, can be localized with respect to the matter that they control and organize, not through a relationship of contact between the external surfaces of a body "that contains" and those of one that is "contained," as it takes place between material entities. Non-material entities, rather, must be localized through "the extension of the capacity to control and organize Lat.
For Aquinas the attempt to localize the soul and its action in specific parts of the brain, such as that brought forward at his times by the interactionism of the Platonists, is totally wrong and misleading cf. Summa TheologiaeI, q. Resorting to this same principle, he justified the omnipresence of God in the universe, for His actual capacity to govern everything and not just a body as in the case of the human soul in each one of us.
A second characteristic of the dual metaphysical theory of the mind, immediately linked to the original localization of the mind with respect to the body in the theory itself, is that it appears connected to an "intentional" theory of knowledge, as much as the other two types of theories are, at least in modern times, dependent upon an exclusively "representational" theory representationism of knowledge.
How the history of modern philosophy teaches us, the emergence of a representational theory of knowledge is nothing more than the epistemological counterpart of the progressive establishment of the absolutization of the axiomatic method in modern mathematics and logic, that identifies in the theory of demonstration and proof the only object of logic as science and as organon of the mathematical and natural sciences. So much the questioning about the truth and the foundation of axioms is well far beyond the interest and the capacity of the axiomatic method, how much, in a similar way, does the questioning about the "thinking thought" the intellectus for the thinkers of the medieval period that formulates ideas and produces logical symbols in a truthful relationship with the object, with respect to the representational theory of knowledge.
A questioning, that on the thinking thought, which limits itself just to the analysis of the "thought which is thought," the thought that manipulates symbols which are already constituted according to logical and formal rules the ratio in medieval terms.
This got to a point in the 19th century when a project was conceived to reduce epistemology and logic to a unique "universal algebra" of thought, reduced to a pure syntactic formalism occupied with the manipulation of graphical "signs", no longer without a symbolic semantic value. The building of a TM is probably the higher expression of the formalist approach to logic and epistemology, but for this very reason it indicates, at the same time, the beginning of an unstoppable decline. It is certainly not due to mere chance that the principle of intentionality came to acquire an ever greater relevance in the contemporary epistemological and logical-foundational debate, as it became increasingly evident that there was on the one hand a failure in the formalist approach to the foundations of logics and mathematics, and, on the other, the insufficiency of the functionalist interpretation in the cognitive sciences.
In the 13th century, when Thomas Aquinas had to face these problems as a philosopher and a theologian, he was in a very similar situation to ours. In a particular way, in the last part of his life, Aquinas, in Paris, had to face up to that "lay" interpretation of the Latin Averroism of Siger of Brabant ca. As an answer to these theories Aquinas proposed his own interpretation of the Aristotelian rational soul as form of the body.
Dualism (Stanford Encyclopedia of Philosophy)
In so doing, he wished to obtain two main results: Dual Theory of the Mind and Spirituality of the Soul 1. As far as the first problem is concerned, that is how to ensure the immateriality of the intellectual faculties, the solution proposed by Aquinas is similar to that which is proposed today by the functionalist theory. The latter, in order to justify why the human being has the capacity of rational thought, particularly the "creative" capacities, hypothesize the existence, "outside" of the system, of a "closure" of the hierarchy of partially self-referential controls that characterizes the living body.
The function of the agent intellect is precisely that of producing a "universal" logical thinking in real time abstraction"correcting its own errors"; a function that cannot be performed by Turing's oracle or by Hofstadter's universal intelligence, but can be always executed by the intentional intelligence of the individual human being: Thomas Aquinas interprets the active component of human intelligence "agent" intellect as a capacity to constantly re-define the context of the problem "possible" intellect in order to adapt it to the single present datum adaequatio intellectus ad rem.
In this way, the passive component of the intellect - its capacity to comprehend in a conscious way, because it is controlled by its active counterpart- can be considered as a tabula rasaaccording to a famous Aristotelian expression.
However, the passive intellect is not a tabula rasa absolute absence of any data in itself, but rather in respect to each new datum that the neurophysiological and cerebral activity presents to the intellect. Aquinas' position differs from what was pursued by the myths of absolute innatism, as meant by John Locke or by the modern Empiricists up to Popperdeceiving Aristotle and the Scholastics.
In fact, rather than speaking of a tabula rasa, we should speak of a tabula which is constantly swept rasata. Due to its capacity to generalize abstraction with respect to all conditioned and singular datum, human knowledge can be applied to, or focus on an infinity of similar cases, becoming in such a way an "a priori" of the mind.
When it results inadequate for a new set of data "knowing of not knowing"the procedure of adaptation can repeat itself indefinitely. Such a closure is nothing but a self-consciousness of non-organic nature, hence not materially conditioned by the past, what the Ancients used to call intellectushaving the capacity to act immediately on itself distinction between the "agent" and the "possible" components of the intellectand therefore capable of intelligere se intelligere to know that it is knowing.
This way of solving the problem of the relationship between the spiritual and the material component of the human psyche has two main consequences. It is a sort of closure on itself of the informational flux, a "black hole", a "singularity" on the informational space that closes on itself. Moreover, it can be partially or totally prevented by the wrong functioning of some of its material sub-structures which control our cerebral activity and that are informed by it, thus creating the illusion, accepted to be the truth by some thinkers, that these cerebral structures would be the "subjects" of human rational operations.
A text by St. In De Anima, I, lec. Here, he distinguishes between sensory cognitive operations, which have the body as both an object and a means of the operation itself, and which can therefore be only partially self-referential, and intellectual cognitive operations, which have the body only as an object, and which can therefore be completely self-referential intellectus intelligit se intelligere.
We just need the "exchange of information" without any violation of the physical principle of energy conservation, as we would say today. Within the context of the ancient physiology of the "corporeal spirits", all of this is explicitly stated by Aquinas of the "pneumatic" non-electric principle of the transmission through a distance of the nervous impulse, before the discoveries of the Italian physiologist Galvani.
In order to be able to talk today in similar terms, the only physical condition we need is that the physical system we are dealing with, that is, the brain, possess a sufficient level of complexity and a sufficient dynamical instability, derived from its nature which is strongly and irreducibly non-linear unpredictability on the medium-long range behaviour, as occurs in chaotic systems. This immediately implies that energetic and informational fluxes cannot be superimposed to each other in such systems, unlike what happens in the stochastic systems studied by statistical mechanics and linear thermodynamics.
In fact, what characterizes chaotic dynamics that dissipates all living systems are "dissipative systems" and "feed" upon free energy subtracted from the environment is that there is a generation of information within them, that proceeds from the microstate to the macrostate, exactly in the opposite direction, from the macrostate to the microstate, through which the system dissipates energy.
The system behaves in an unpredictable way with respect to what we knew about it from the initial conditions Although each individual quasi-periodical trajectory within the space of the states of the system is predictable step by step, it is a characteristic of the system to "jump" in a way that is absolutely unpredictable from one trajectory to another. The unpredictability of the macrostate is therefore generated from the microstate of the trajectories of particles that compose the system.
In a classic thermodynamic system, the two energetic and informational fluxes proceed instead in the same direction from the macrostate to the microstate, meaning that as soon as the system is described in terms of its microstate, its behaviour becomes perfectly predictable cf. On the one hand, being of spiritual nature, it can be considered capable of autonomous subsistence and must be therefore in some way a "substance," as it was intended by the Platonic dualist.
On the other hand, according to the principles of Christian anthropology regarding the person, it must be considered a component, and therefore "part" of a unique psychophysical substance, that is the person. At this point it is clear that if we do not want to fall into contradiction, the soul must be considered as "substance", but in a way different from what is intended for the person in its completeness.
Thomas solves the question by referring to the general Aristotelian doctrine on the category of "substance", as discussed by the Stagirite in Book V of the Categories. According to this doctrine, "substance" can be intended in three main ways. In the first way, as a being that is defined and complete in its nature and that exists as an individual "first" substance: In the second way, the substance can be intended as a defined and complete being that exists only in the individuals, understood as "parts of them" "second" substance: An analogy for the notion of substance as intended in this second sense can be found in logic, in the notion of property that defines an "ordinary class" of elements, a class that does not belong to itself because it is determined by a non "autologic" predicate, that does not apply to itself.
In such a way "humanity", intended as a property that defines all human beings and only human beings, "is not itself a human being," as Aristotle would say. In fact, as Russell discovered, if we consider the notion of "total class of all the ordinary classes," the class of all the classes that do not belong to themselves, whenever we ask ourselves if such a class does or does not belong to itself, we soon find an antinomy.
Finally, there is a third way of speaking of substance. A substance can be considered as a being that is defined, but non complete in its nature, and that exists in the individuals as "part of them", a part that, however, determines the totality to which it belongs "third" substance or "substantial form".
An analogy to the notion of substance as intended in this third meaning can be found again in logic, in the notion of property that determines a "non-ordinary class" of elements, a class that belongs to itself because it is determined by an autologic predicate, that can be applied to itself.
For example, "polysyllabic," intended as a property that determines all the polysyllabic words, is itself a polysyllabic word, and therefore belongs to the class that it defines.
Regarding this matter Aristotle used the physical, indeed biological, example of the "feet," that although being part of the totality of an animal individual, nonetheless they are a part that can define the totality to which they belong. In fact, an animal can be defined as "biped" or "quadruped. The soul is the form of a first, individual substance, that is the person, thus it is part of that, which is however specified by this part. Person means in fact "individual substance of a rational nature," according to the classic definition given by Boethius.
The problem of the survival of the rational soul after death still remains unsolved. According to the previous proof, the soul has its own operations that it "must" execute independently from the organs of the body. Thus, as Aquinas states, if it has the capability to act by itself per sethen it must also have the capability to be by itself cf. Quaestio De Anima, a. However, it does not have the being by itself as a "first" substance, but rather as a "third" substance, as a part of that totality that is specified by it.
In other terms, in order to continue with the Aristotelian example of the hand and the body, and of how the hand cannot survive if separated from the body, with which the former constantly exchanges matter and energy for its vital operations of metabolic nature, analogously the mind, in order to perform its cognitive operations, needs to continually exchange information with the body, and through it with the rest of the world.
In other words, a living organism can be defined as such if it is able to exert its characteristic vital operations. Nowadays, it is possible to put an explanted organ in a compatible chemical environment and maintain it for a short time in order to allow it to carry out its main metabolic operations up until the moment when it is transplanted in a new organism. The characteristic vital operations of the human mind are not, however, of chemical-metabolic type, but rather of the "informational" type.
Therefore, how Thomas Aquinas already stated, the human mind can continue to carry out its vital operations hence to "live" after death provided that it receives from a source other than the body the pieces of information species on which to operate.
The question posed by the philosopher Thomas, doctor humanitatis, was answered by the theologian Thomas, doctor angelicus. Dualist views the subject of this entry say that the mental and the physical are both real and neither can be assimilated to the other.
For the various forms that dualism can take and the associated problems, see below. In sum, we can say that there is a mind-body problem because both consciousness and thought, broadly construed, seem very different from anything physical and there is no convincing consensus on how to build a satisfactorily unified picture of creatures possessed of both a mind and a body. In the classical and mediaeval periods, it was the intellect that was thought to be most obviously resistant to a materialistic account: The classical emphasis originates in Plato's Phaedo.
Plato believed that the true substances are not physical bodies, which are ephemeral, but the eternal Forms of which bodies are imperfect copies. It is their connection with intelligibility that is relevant to the philosophy of mind.
Because Forms are the grounds of intelligibility, they are what the intellect must grasp in the process of understanding. In Phaedo Plato presents a variety of arguments for the immortality of the soul, but the one that is relevant for our purposes is that the intellect is immaterial because Forms are immaterial and intellect must have an affinity with the Forms it apprehends 78b4—84b8.
This affinity is so strong that the soul strives to leave the body in which it is imprisoned and to dwell in the realm of Forms. It may take many reincarnations before this is achieved.
Plato's dualism is not, therefore, simply a doctrine in the philosophy of mind, but an integral part of his whole metaphysics. One problem with Plato's dualism was that, though he speaks of the soul as imprisoned in the body, there is no clear account of what binds a particular soul to a particular body.
Their difference in nature makes the union a mystery. Aristotle did not believe in Platonic Forms, existing independently of their instances. This enabled Aristotle to explain the union of body and soul by saying that the soul is the form of the body. This means that a particular person's soul is no more than his nature as a human being.
Because this seems to make the soul into a property of the body, it led many interpreters, both ancient and modern, to interpret his theory as materialistic. The interpretation of Aristotle's philosophy of mind—and, indeed, of his whole doctrine of form—remains as live an issue today as it was immediately after his death Robinson and ; Nussbaum ; Rorty and Nussbaum, eds, Nevertheless, the text makes it clear that Aristotle believed that the intellect, though part of the soul, differs from other faculties in not having a bodily organ.
His argument for this constitutes a more tightly argued case than Plato's for the immateriality of thought and, hence, for a kind of dualism. He argued that the intellect must be immaterial because if it were material it could not receive all forms. Just as the eye, because of its particular physical nature, is sensitive to light but not to sound, and the ear to sound and not to light, so, if the intellect were in a physical organ it could be sensitive only to a restricted range of physical things; but this is not the case, for we can think about any kind of material object De Anima III,4; a10—b9.
As it does not have a material organ, its activity must be essentially immaterial. It is common for modern Aristotelians, who otherwise have a high view of Aristotle's relevance to modern philosophy, to treat this argument as being of purely historical interest, and not essential to Aristotle's system as a whole.
Kenny argues that Aristotle's theory of mind as form gives him an account similar to Rylefor it makes the soul equivalent to the dispositions possessed by a living body.
These issues might seem to be of purely historical interest. But we shall see in below, in section 4. The identification of form and substance is a feature of Aristotle's system that Aquinas effectively exploits in this context, identifying soul, intellect and form, and treating them as a substance.
See, for example, AquinasPart I, questions 75 and But though the form and, hence, the intellect with which it is identical are the substance of the human person, they are not the person itself. The soul, though an immaterial substance, is the person only when united with its body.
Without the body, those aspects of its personal memory that depend on images which are held to be corporeal will be lost. See AquinasPart I, question The more modern versions of dualism have their origin in Descartes' Meditations, and in the debate that was consequent upon Descartes' theory. Descartes was a substance dualist.
He believed that there were two kinds of substance: Descartes' conception of the relation between mind and body was quite different from that held in the Aristotelian tradition. For Aristotle, there is no exact science of matter. How matter behaves is essentially affected by the form that is in it. You cannot combine just any matter with any form—you cannot make a knife out of butter, nor a human being out of paper—so the nature of the matter is a necessary condition for the nature of the substance.
But the nature of the substance does not follow from the nature of its matter alone: Matter is a determinable made determinate by form. This was how Aristotle thought that he was able to explain the connection of soul to body: The belief in the relative indeterminacy of matter is one reason for Aristotle's rejection of atomism. If matter is atomic, then it is already a collection of determinate objects in its own right, and it becomes natural to regard the properties of macroscopic substances as mere summations of the natures of the atoms.
Although, unlike most of his fashionable contemporaries and immediate successors, Descartes was not an atomist, he was, like the others, a mechanist about the properties of matter. Bodies are machines that work according to their own laws. Except where there are minds interfering with it, matter proceeds deterministically, in its own right. Descartes opted for the pineal gland, mainly because it is not duplicated on both sides of the brain, so it is a candidate for having a unique, unifying function.
The main uncertainty that faced Descartes and his contemporaries, however, was not where interaction took place, but how two things so different as thought and extension could interact at all. This would be particularly mysterious if one had an impact view of causal interaction, as would anyone influenced by atomism, for whom the paradigm of causation is like two billiard balls cannoning off one another.
Various of Descartes' disciples, such as Arnold Geulincx and Nicholas Malebranche, concluded that all mind-body interactions required the direct intervention of God. The appropriate states of mind and body were only the occasions for such intervention, not real causes.
Now it would be convenient to think that occasionalists held that all causation was natural except for that between mind and body. In fact they generalized their conclusion and treated all causation as directly dependent on God.
Why this was so, we cannot discuss here. Descartes' conception of a dualism of substances came under attack from the more radical empiricists, who found it difficult to attach sense to the concept of substance at all. Locke, as a moderate empiricist, accepted that there were both material and immaterial substances. Berkeley famously rejected material substance, because he rejected all existence outside the mind.
Finally, he decided that the self, conceived as something over and above the ideas of which it was aware, was essential for an adequate understanding of the human person. Although the self and its acts are not presented to consciousness as objects of awareness, we are obliquely aware of them simply by dint of being active subjects. Hume rejected such claims, and proclaimed the self to be nothing more than a concatenation of its ephemeral contents.
In fact, Hume criticised the whole conception of substance for lacking in empirical content: This position has been labelled bundle dualism, and it is a special case of a general bundle theory of substance, according to which objects in general are just organised collections of properties.
The problem for the Humean is to explain what binds the elements in the bundle together. This is an issue for any kind of substance, but for material bodies the solution seems fairly straightforward: For the mind, mere causal connection is not enough; some further relation of co-consciousness is required.
We shall see in 5. One should note the following about Hume's theory. His bundle theory is a theory about the nature of the unity of the mind. As a theory about this unity, it is not necessarily dualist.
Parfitand Shoemakerch. In general, physicalists will accept it unless they wish to ascribe the unity to the brain or the organism as a whole. Before the bundle theory can be dualist one must accept property dualism, for more about which, see the next section.
A crisis in the history of dualism came, however, with the growing popularity of mechanism in science in the nineteenth century. This means that everything that happens follows from and is in accord with the laws of physics. There is, therefore, no scope for interference in the physical world by the mind in the way that interactionism seems to require. According to the mechanist, the conscious mind is an epiphenomenon a notion given general currency by T.
In this way, the facts of consciousness are acknowledged but the integrity of physical science is preserved. However, many philosophers found it implausible to claim such things as the following; the pain that I have when you hit me, the visual sensations I have when I see the ferocious lion bearing down on me or the conscious sense of understanding I have when I hear your argument—all have nothing directly to do with the way I respond.
It is very largely due to the need to avoid this counterintuitiveness that we owe the concern of twentieth century philosophy to devise a plausible form of materialist monism. But, although dualism has been out of fashion in psychology since the advent of behaviourism Watson and in philosophy since Rylethe argument is by no means over. Some distinguished neurologists, such as Sherrington and Eccles Popper and Eccles have continued to defend dualism as the only theory that can preserve the data of consciousness.
Amongst mainstream philosophers, discontent with physicalism led to a modest revival of property dualism in the last decade of the twentieth century.
At least some of the reasons for this should become clear below. Ontology There are various ways of dividing up kinds of dualism. One natural way is in terms of what sorts of things one chooses to be dualistic about. The most common categories lighted upon for these purposes are substance and property, giving one substance dualism and property dualism. There is, however, an important third category, namely predicate dualism. As this last is the weakest theory, in the sense that it claims least, I shall begin by characterizing it.
For a mental predicate to be reducible, there would be bridging laws connecting types of psychological states to types of physical ones in such a way that the use of the mental predicate carried no information that could not be expressed without it. An example of what we believe to be a true type reduction outside psychology is the case of water, where water is always H2O: But the terms in many of the special sciences that is, any science except physics itself are not reducible in this way.
Not every hurricane or every infectious disease, let alone every devaluation of the currency or every coup d'etat has the same constitutive structure. These states are defined more by what they do than by their composition or structure. Their names are classified as functional terms rather than natural kind terms.
It goes with this that such kinds of state are multiply realizable; that is, they may be constituted by different kinds of physical structures under different circumstances. Because of this, unlike in the case of water and H2O, one could not replace these terms by some more basic physical description and still convey the same information. It is widely agreed that many, if not all, psychological states are similarly irreducible, and so psychological predicates are not reducible to physical descriptions and one has predicate dualism.
The classic source for irreducibility in the special sciences in general is Fodorand for irreducibility in the philosophy of mind, Davidson Property dualism can be seen as a step stronger than predicate dualism.
One might say that we need more than the language of physics to describe and explain the weather, but we do not need more than its ontology.
There is token identity between each individual hurricane and a mass of atoms, even if there is no type identity between hurricanes as kinds and some particular structure of atoms as a kind. Genuine property dualism occurs when, even at the individual level, the ontology of physics is not sufficient to constitute what is there. The irreducible language is not just another way of describing what there is, it requires that there be something more there than was allowed for in the initial ontology.
In the case of mind, property dualism is defended by those who argue that the qualitative nature of consciousness is not merely another way of categorizing states of the brain or of behaviour, but a genuinely emergent phenomenon. One is that of substance, the other is the dualism of these substances.
A substance is characterized by its properties, but, according to those who believe in substances, it is more than the collection of the properties it possesses, it is the thing which possesses them. So the mind is not just a collection of thoughts, but is that which thinks, an immaterial substance over and above its immaterial states.
Properties are the properties of objects. If one is a property dualist, one may wonder what kinds of objects possess the irreducible or immaterial properties in which one believes. One can use a neutral expression and attribute them to persons, but, until one has an account of person, this is not explanatory.
One might attribute them to human beings qua animals, or to the brains of these animals. Then one will be holding that these immaterial properties are possessed by what is otherwise a purely material thing. But one may also think that not only mental states are immaterial, but that the subject that possesses them must also be immaterial.
Then one will be a dualist about that to which mental states and properties belong as well about the properties themselves. Now one might try to think of these subjects as just bundles of the immaterial states. This is Hume's view. But if one thinks that the owner of these states is something quite over and above the states themselves, and is immaterial, as they are, one will be a substance dualist. Lowe, for example, is a substance dualist, in the following sense.
He holds that a normal human being involves two substances, one a body and the other a person. The latter is not, however, a purely mental substance that can be defined in terms of thought or consciousness alone, as Descartes claimed.
But persons and their bodies have different identity conditions and are both substances, so there are two substances essentially involved in a human being, hence this is a form of substances dualism. Lowe claims that his theory is close to P. Strawson'swhilst admitting that Strawson would not have called it substance dualism. Interaction If mind and body are different realms, in the way required by either property or substance dualism, then there arises the question of how they are related.
Common sense tells us that they interact: I shall now consider briefly the problems for interactionism, and its main rivals, epiphenomenalism and parallelism.
That this is so is one of our common-sense beliefs, because it appears to be a feature of everyday experience. The physical world influences my experience through my senses, and I often react behaviourally to those experiences.
My thinking, too, influences my speech and my actions. There is, therefore, a massive natural prejudice in favour of interactionism.
It has been claimed, however, that it faces serious problems some of which were anticipated in section 1. The simplest objection to interaction is that, in so far as mental properties, states or substances are of radically different kinds from each other, they lack that communality necessary for interaction. But if causation is either by a more ethereal force or energy or only a matter of constant conjunction, there would appear to be no problem in principle with the idea of interaction of mind and body.
Even if there is no objection in principle, there appears to be a conflict between interactionism and some basic principles of physical science. For example, if causal power was flowing in and out of the physical system, energy would not be conserved, and the conservation of energy is a fundamental scientific law.
Various responses have been made to this. One suggestion is that it might be possible for mind to influence the distribution of energy, without altering its quantity. See Averill and Keating Another response is to challenge the relevance of the conservation principle in this context.
Robins Collins has claimed that the appeal to conservation by opponents of interactionism is something of a red herring because conservation principles are not ubiquitous in physics. He argues that energy is not conserved in general relativity, in quantum theory, or in the universe taken as a whole. Why then, should we insist on it in mind-brain interaction? This is a very natural assumption, but it is not justified if causal overdetermination of behaviour is possible. There could then be a complete physical cause of behaviour, and a mental one.
The strongest intuitive objection against overdetermination is clearly stated by Mills For X to be a cause of Y, X must contribute something to Y. The only way a purely mental event could contribute to a purely physical one would be to contribute some feature not already determined by a purely physical event.
But if physical closure is true, there is no feature of the purely physical effect that is not contributed by the purely physical cause. Hence interactionism violates physical closure after all. Mills says that this argument is invalid, because a physical event can have features not explained by the event which is its sufficient cause. It is this kind of feature that the mental event would have to cause, but physical closure leaves no room for this.
These matters are still controversial. The problem with closure of physics may be radically altered if physical laws are indeterministic, as quantum theory seems to assert. If physical laws are deterministic, then any interference from outside would lead to a breach of those laws. But if they are indeterministic, might not interference produce a result that has a probability greater than zero, and so be consistent with the laws?
This way, one might have interaction yet preserve a kind of nomological closure, in the sense that no laws are infringed. Because it involves assessing the significance and consequences of quantum theory, this is a difficult matter for the non-physicist to assess. Some argue that indeterminacy manifests itself only on the subatomic level, being cancelled out by the time one reaches even very tiny macroscopic objects: For discussion of this, see Eccles, and Popper and Eccles Still others argue that quantum indeterminacy manifests itself directly at a high level, when acts of observation collapse the wave function, suggesting that the mind may play a direct role in affecting the state of the world Hodgson ; Stapp According to this theory, mental events are caused by physical events, but have no causal influence on the physical.
I have introduced this theory as if its point were to avoid the problem of how two different categories of thing might interact. In fact, it is, at best, an incomplete solution to this problem. If it is mysterious how the non-physical can have it in its nature to influence the physical, it ought to be equally mysterious how the physical can have it in its nature to produce something non-physical.
But that this latter is what occurs is an essential claim of epiphenomenalism. For development of this point, see Green— There are at least three serious problems for epiphenomenalism. First, as I indicated in section 1, it is profoundly counterintuitive. What could be more apparent than that it is the pain that I feel that makes me cry, or the visual experience of the boulder rolling towards me that makes me run away?
At least one can say that epiphenomenalism is a fall-back position: The second problem is that, if mental states do nothing, there is no reason why they should have evolved. This objection ties in with the first: Frank Jackson replies to this objection by saying that it is the brain state associated with pain that evolves for this reason: Evolution is full of useless or even harmful by-products.
For example, polar bears have evolved thick coats to keep them warm, even though this has the damaging side effect that they are heavy to carry.
Jackson's point is true in general, but does not seem to apply very happily to the case of mind. The heaviness of the polar bear's coat follows directly from those properties and laws which make it warm: But with mental states, dualistically conceived, the situation is quite the opposite. The laws of physical nature which, the mechanist says, make brain states cause behaviour, in no way explain why brain states should give rise to conscious ones.
The laws linking mind and brain are what Feigl calls nomological danglers, that is, brute facts added onto the body of integrated physical law. Why there should have been by-products of that kind seems to have no evolutionary explanation. The third problem concerns the rationality of belief in epiphenomenalism, via its effect on the problem of other minds.
It is natural to say that I know that I have mental states because I experience them directly. But how can I justify my belief that others have them? I know that certain of my mental states are correlated with certain pieces of behaviour, and so I infer that similar behaviour in others is also accompanied by similar mental states. Many hold that this is a weak argument because it is induction from one instance, namely, my own.
I seem to know from my own case that mental events can be the explanation of behaviour, and I know of no other candidate explanation for typical human behaviour, so I postulate the same explanation for the behaviour of others. But if epiphenomenalism is true, my mental states do not explain my behaviour and there is a physical explanation for the behaviour of others.
It is explanatorily redundant to postulate such states for others. I know, by introspection, that I have them, but is it not just as likely that I alone am subject to this quirk of nature, rather than that everyone is? For more detailed treatment and further reading on this topic, see the entry epiphenomenalism.
The parallelist preserves both realms intact, but denies all causal interaction between them. They run in harmony with each other, but not because their mutual influence keeps each other in line. That they should behave as if they were interacting would seem to be a bizarre coincidence.
This is why parallelism has tended to be adopted only by those—like Leibniz—who believe in a pre-established harmony, set in place by God. The progression of thought can be seen as follows. Descartes believes in a more or less natural form of interaction between immaterial mind and material body.
Malebranche thought that this was impossible naturally, and so required God to intervene specifically on each occasion on which interaction was required. Leibniz decided that God might as well set things up so that they always behaved as if they were interacting, without particular intervention being required. Outside such a theistic framework, the theory is incredible. Even within such a framework, one might well sympathise with Berkeley's instinct that once genuine interaction is ruled out one is best advised to allow that God creates the physical world directly, within the mental realm itself, as a construct out of experience.
Because this argument has its own entry see the entry qualia: One should bear in mind, however, that all arguments against physicalism are also arguments for the irreducible and hence immaterial nature of the mind and, given the existence of the material world, are thus arguments for dualism. The knowledge argument asks us to imagine a future scientist who has lacked a certain sensory modality from birth, but who has acquired a perfect scientific understanding of how this modality operates in others.
This scientist—call him Harpo—may have been born stone deaf, but become the world's greatest expert on the machinery of hearing: Suppose that Harpo, thanks to developments in neurosurgery, has an operation which finally enables him to hear. It is suggested that he will then learn something he did not know before, which can be expressed as what it is like to hear, or the qualitative or phenomenal nature of sound.
These qualitative features of experience are generally referred to as qualia. If Harpo learns something new, he did not know everything before. He knew all the physical facts before. So what he learns on coming to hear—the facts about the nature of experience or the nature of qualia—are non-physical.
This establishes at least a state or property dualism. See Jackson ; Robinson There are at least two lines of response to this popular but controversial argument. This essentially behaviouristic account is exactly what the intuition behind the argument is meant to overthrow.
Putting ourselves in Harpo's position, it is meant to be obvious that what he acquires is knowledge of what something is like, not just how to do something. Such appeals to intuition are always, of course, open to denial by those who claim not to share the intuition. Some ability theorists seem to blur the distinction between knowing what something is like and knowing how to do something, by saying that the ability Harpo acquires is to imagine or remember the nature of sound.
In this case, what he acquires the ability to do involves the representation to himself of what the thing is like. But this conception of representing to oneself, especially in the form of imagination, seems sufficiently close to producing in oneself something very like a sensory experience that it only defers the problem: The other line of response is to argue that, although Harpo's new knowledge is factual, it is not knowledge of a new fact. Rather, it is new way of grasping something that he already knew.
Demonstrative concepts pick something out without saying anything extra about it. Similarly, the scientific knowledge that Harpo originally possessed did not enable him to anticipate what it would be like to re-express some parts of that knowledge using the demonstrative concepts that only experience can give one. The knowledge, therefore, appears to be genuinely new, whereas only the mode of conceiving it is novel.
Proponents of the epistemic argument respond that it is problematic to maintain both that the qualitative nature of experience can be genuinely novel, and that the quality itself be the same as some property already grasped scientifically: Furthermore, experiencing does not seem to consist simply in exercising a particular kind of concept, demonstrative or not. When Harpo has his new form of experience, he does not simply exercise a new concept; he also grasps something new—the phenomenal quality—with that concept.
How decisive these considerations are, remains controversial. This, however, can be disputed. The argument from predicate to property dualism moves in two steps, both controversial. The first claims that the irreducible special sciences, which are the sources of irreducible predicates, are not wholly objective in the way that physics is, but depend for their subject matter upon interest-relative perspectives on the world. This means that they, and the predicates special to them, depend on the existence of minds and mental states, for only minds have interest-relative perspectives.
The second claim is that psychology—the science of the mental—is itself an irreducible special science, and so it, too, presupposes the existence of the mental. Mental predicates therefore presuppose the mentality that creates them: First, let us consider the claim that the special sciences are not fully objective, but are interest-relative.
A mass of matter could be characterized as a hurricane, or as a collection of chemical elements, or as mass of sub-atomic particles, and there be only the one mass of matter. But such different explanatory frameworks seem to presuppose different perspectives on that subject matter. This is where basic physics, and perhaps those sciences reducible to basic physics, differ from irreducible special sciences. On a realist construal, the completed physics cuts physical reality up at its ultimate joints: If scientific realism is true, a completed physics will tell one how the world is, independently of any special interest or concern: It would seem that, by contrast, a science which is not nomically reducible to physics does not take its legitimation from the underlying reality in this direct way.
Rather, such a science is formed from the collaboration between, on the one hand, objective similarities in the world and, on the other, perspectives and interests of those who devise the science. The concept of hurricane is brought to bear from the perspective of creatures concerned about the weather.
Creatures totally indifferent to the weather would have no reason to take the real patterns of phenomena that hurricanes share as constituting a single kind of thing.PHILOSOPHY - Mind: Mind-Body Dualism [HD]
With the irreducible special sciences, there is an issue of saliencewhich involves a subjective component: The entities of metereology or biology are, in this respect, rather like Gestalt phenomena.
Even accepting this, why might it be thought that the perspectivality of the special sciences leads to a genuine property dualism in the philosophy of mind? It might seem to do so for the following reason. Having a perspective on the world, perceptual or intellectual, is a psychological state. So the irreducible special sciences presuppose the existence of mind. If one is to avoid an ontological dualism, the mind that has this perspective must be part of the physical reality on which it has its perspective.
Mind and Body Problem: From Plato to Sadra via Descartes
But psychology, it seems to be almost universally agreed, is one of those special sciences that is not reducible to physics, so if its subject matter is to be physical, it itself presupposes a perspective and, hence, the existence of a mind to see matter as psychological.
If this mind is physical and irreducible, it presupposes mind to see it as such. We seem to be in a vicious circle or regress. We can now understand the motivation for full-blown reduction. A true basic physics represents the world as it is in itself, and if the special sciences were reducible, then the existence of their ontologies would make sense as expressions of the physical, not just as ways of seeing or interpreting it.
The irreducibility of the special sciences creates no problem for the dualist, who sees the explanatory endeavor of the physical sciences as something carried on from a perspective conceptually outside of the physical world.