Dualism (philosophy of mind)

As an ontological dualism philosophical positions are referred to, who assume that everything is (ontology ) in two mutually exclusive types of entities or substances decays ( dualism ), and describe whether and how interactions between these types are possible. In the Western philosophical tradition tangible and intangible ( " spiritual " ) are entities juxtaposed. The ontological dualism is closely intertwined with the metaphysical dualism historically and thematically; The starting point is often the effort to resolve the mind-body problem.

Ontological dualism

Diversity of ontological dualisms

Although the classical ontological dualism between material and immaterial, especially mental, entities differs, is also repeatedly claimed the immateriality of other phenomena, such as aesthetic and moral qualities, numbers and propositions. As a candidate for immaterial entities dualists are all the phenomena that can not be explained by the Natural Sciences and resist such a reduction. However, irreducibility not evidence of immateriality, since there are also attempts to formulate nonreductive materialisms.

Dualisms differ not only in the answer to the question of which entities should be considered as immaterial. There are also different ways to describe the intangible entities ontologically. Firstly, a substance dualism is possible that emanates from tangible and intangible objects. On the other hand, however, can also be represented a property dualism, which is monistic in terms of objects. Eigenschaftsdualistische positions have a high popularity in current philosophy of mind, while classic Substanzdualismen there are now more rare.


Interactionist dualism

The interactionist dualism is considered classic version of substance dualism, and for example, was represented by René Descartes. The interactionist dualism indicate that there are tangible and intangible entities that interact with each other causally. When a person is about being tickled, the stimuli are registered by the material body and forwarded to the brain. At some point the material processes then act on the immaterial mind and produce a tickling experience. Conversely solve mental states, from about thoughts or emotions, bodily processes. Descartes suspected as a place of interaction, the pineal gland, a neural structure that is distinguished by the fact that it occurs in the brain only once.

Against the interactionist dualism has been argued time and again that he is empirically implausible, since the neurosciences could find no such Interaktionsort between mind and brain. Rather, could be for each neural process a neural cause, see, so that nowhere would a necessity of the interference of the mind. You can also take this general objection to the interactionist dualism: if such a position were true, the idea of ​​causal closure of the physical world would have to be abandoned. Thus the argument is meant that there is also a purely physical cause for every physical event. This must be a dualist interactionist dispute, because he believes that some physical events are only caused by intangible events. Now, however, argued by Nichtdualisten that the causal unity of the world is not only a plausible assumption, but also empirically quite well documented.

Karl Popper and John Eccles, the most famous representatives of interactionist dualism in the 20th century, attempted to evade this objection by Misplaced the interaction between mind and brain on a subatomic level.

Above all, Popper argued against the unity of the physical world with its three-world theory, which would shed a new light on the mind-body problem. According to this theory objects of the world 3 (mental objects ) are indeed abstract, but nonetheless real, and even more powerful tools to change the world one (physical world).

The objects of the world 3 but could not be effective by itself; they are dependent of the World 2 ( human consciousness ) received and to be " realized ". In this respect they resemble, for example, viruses that do not have their own metabolism, so likewise can not be active on its own, but can still be cause for specific effects ( viral diseases).

Against the objection that we do not know how the action of mind on physical objects is possible, Popper argued, we would actually not even sure how it was possible that physical objects can interact with other physical objects. It was just an (evident ) fact that this is possible.

Nichtinteraktionistischer dualism

A nichtinteraktionistische variant of substance dualism was developed by Gottfried Wilhelm Leibniz, who argued that mind and body in any way interact. This theory of psychophysical parallelism has, however, to explain the problem, such as the relationships between mental and physical states come about. Finally, as has the mental (or better mental ) state of thirst usually Drinking result in the physical event, but what seems inexplicable when the mind can not act on the body. Leibniz tried to rebut this argument with an analogy. He explained that the mind and body behave like two parallel clocks to each other. The event is perfectly coordinated, even though no causal interaction exists. Now, one can but wonder why such a parallelism exists. Leibniz explained that this was a means of God.

A related metaphysical position of occasionalism, comes from Nicolas Malebranche. According to the occasionalism have on each other mind and body no causal influence. However, the changes of body and mind of God to be registered, which triggers the corresponding mental or physical processes. The causality, which seemingly combines the spiritual and material events, is here solely attributed to the fact that repeated the man observed the occurrence of an event as a result of other events and draws the wrong conclusion of a causal connection. This - so the theory goes - but is not the evidence of causality. Rather, each event is a discrete, self-contained operation; the world in the course of time consists of a variety of ever new worlds, each of which new ex nihilo by God - is created - out of nothing. In this way, try Occasionalists to solve the problem of mind - matter interaction - there is no causal interaction takes, God alone is the cause of all - spiritual and material - events. The occasionalism, as well as the psycho-physical parallelism, today hardly represented.

Another variant of the dualism epiphenomenalism, which was approximately represented by Thomas Henry Huxley. Epiphänomenalisten believe that physical states can indeed act on mental causal, but not mental states to physical. Such a position is compatible with the idea of ​​causal closure of the world and can still explain how the connections between mind and body come about. These features have led to even today restricted variants of epiphenomenalism are represented. However, these positions are mostly eigenschaftsdualistische Epiphänomenalismen. So you assert the existence of intangible, causally ineffective characteristics and not the existence of such objects or substances. Even against epiphenomenalism numerous objections have been raised. So is doubtful about how one can know of mental states at all if they have no effect. It was also always argued again that the idea of causal completely ineffective entities not be coherent.


Eigenschaftsdualistische positions have in today's philosophical debate a higher popularity than Substanzdualismen. Eigenschaftsdualisten argue that a person is not made ​​up of two substances ( mind and body ) is composed. Rather, they argue that it (the person ) was only an object, but have physical and mental characteristics. Often Eigenschaftsdualisten of the qualia, ie the subjective experience levels, regarded as non-physical properties, since in these the reducibility remains doubtful to physical or physical states.

In today's philosophy of mind mainly the eigenschaftsdualistischen arguments of David Chalmers and Frank Cameron Jackson are discussed, but the historical roots of this heading go back much further. Already Baruch de Spinoza's neutral monism was based on a substance, the material and spiritual qualities has. In the 19th century an analogous position was made popular about by Ernst Haeckel.

The property has dualism continues to struggle with similar problems of substance dualism, he needs to explain the causal efficacy of mental states, mental causation. If the mental characteristics have a causal influence on the material world, the Eigenschaftsdualist seems to have to deny the causal unity of the world, which, as described above, leads to problems. Should the Eigenschaftsdualist however, waive the causal efficacy of mental properties, it must represent a form of epiphenomenalism. However, not all Eigenschaftsdualisten accept to face such a dilemma. Some argue that the world is causally closed, thus giving a physical cause for every physical event, and mental properties are causally efficacious yet. Such philosophers must explain that some events of physical and mental characteristics are caused by the same time.

Arguments for dualism


The classic argument for dualism has been formulated by Descartes in the Meditations on First Philosophy. Descartes argued that he could imagine clearly that mind and body are separate. According Descartes mean the fact that it is conceivable, however, that it is possible in principle. However, if it even is possible in principle that the mind and the body exist separately from each other so they can not be identical. So there must be an immaterial spirit. Such an argument must, inter alia, to put up the question why the conceivability of stepping apart from mind and body also should already prove its possibility. Descartes stated that the structure of the world is so that everything you could imagine clearly, can also be set-up by God, that was possible. However, it is not clear whether such an argument can have success. Not only that, it presupposes the existence of God ( Natural Theology), it is also not clear why a theist must accept the assumption that God could set up everything you can think clearly.

Despite these problems Vorstellbarkeitsargumente still have a certain degree of popularity, partly because they have been formulated by Saul Kripke in a new way. Kripke's goal is to show that conceivability implies possibility, which would make Descartes ' argument again plausible. Such an implication seems initially unlikely, as conditions seem to imagine that is not possible. So it may seem inconceivable that water and H2O are not identical. It is about designing the thought experiment that the early chemists are encountered in the study of water not H2O but a different compound XYZ. This seems to be imagining a situation in which water and H2O are not identical. Nevertheless, this situation is obviously not possible, since water and H2O are precisely identical. And if two phenomena A and B are identical, then one can never A without B or B occur without A.

Kripke then argues that the thought experiment does not lead to the notion of a situation that is not H2O in the water. Instead, imagine the thought experiment before a case in which a substance (liquid, transparent, odorless, boiling at 100 ° C, etc.) has the same macro properties such as water is not H2O. However, this substance was not just water, since water is identical to H2O, but another, the water similar substance. Kripke holds this result for generalized: Whenever a situation to imagine, but not seem possible, this impression can be explained away by an analysis of the reference relations. Is Kripke's diagnosis, so there is no case in which X is conceivable but not possible. So if it is conceivable that the mind occurs without the body, then this is also possible, and then they can not be identical. However, objections are also possible against Kripke's argument. So one can deny that it is even conceivable that the spirit auftrete without the body.

Qualia -based arguments

Many contemporary arguments for the ontological dualism based on the phenomenon of qualia. Qualia is called the subjective experience levels of mental states, or about the Blue life that goes along with the perception of a blue object. Now it is often argued that the Qualia intangible properties are, since they are not on physical - could be reduced properties - such as neural. Materialists hold against the various arguments. While some sat on the reducibility of qualia explain nonreductive materialists that the Qualia material, but non-reducible properties can be.

Dualists have further developed the Qualia arguments in different ways. One popular version is from the Australian philosopher Frank Cameron Jackson, who formulated a thought experiment with a super scientist named "Mary": Mary is a specialized color vision physiologist who is trapped in a black-and- white lab since birth and have never seen colors has. She knows all the physical facts about seeing colors, but do not know how colors look. Jackson's argument against materialism is now quite short: Mary knows all the physical facts about seeing colors. Yet you do not know all the facts about seeing colors. So there are non- physical facts. So dualism is true.