¶ … Dualism." It discusses the basic idea of the term dualism and why it is rejected by science. What is Dualism?

Dualism is the metaphysical principle that there are two substances, i.e., distinctive and autonomous kinds of being, one material and the other spiritual. Material substance is defined as physical and is declared to be the fundamental certainty of the empirical world, i.e., the world we see, hear, etc., and measure with our senses and technical instruments that extend the range of the senses, such as electron microscopes, telescopes, radar, etc. The spiritual world is usually described negatively as the non-physical, non-material reality underlying the non-empirical world, variously called the psychological, the mental, or the spiritual world. The principle of dualism predates scientific study of behavior, and the assumption that 'the person' comprises of two systems, mental and physical, provides epistemic justification for asserting that behavioral measures count as evidence of other systems. All through the psychological literature, behavior is termed as apparent scientific evidence of the presence or action or malfunction of systems, processes, or events internal to the person.(Selk, Eugene E, Body, Soul, and Life Everlasting: Biblical Anthropology and the Monism-Dualism Debate., Theological Studies, 12-01-2001, pp 871.)

So what actually is "Dualism"? In dualism, 'mind' is contrasted with 'body', but at different times, different aspects of the mind have been the centre of attention. In the classical and mediaeval periods, it was the intellect that was thought to be most obviously resistant to a materialistic account from Descartes on, the main stumbling block to materialist monism was supposed to be 'consciousness', of which phenomenal consciousness or sensation came to be considered as the paradigm instance. Dualism resolved a conflict for Descartes between his materialist interests and important religious concerns of his time by allowing him to distinguish mechanical behavior from behavior generated by something called 'free will'. The assumption of two domains continues to underpin scientific accounts of human action. Descartes was a scientist who not only wanted to contribute to empirical knowledge, but he also felt the strictures of the Roman Catholic Church. He yearned for the kind of freedom to pursue scientific endeavors that Galileo had not found, and so Descartes proposed a solution to this practical difficulty.

Descartes felt pulled in two directions on the one hand, he was a good Catholic on the other hand, he was a good scientist but the two endeavors seemed to be in conflict. The solution to the problem lay in separating these two commitments into different realms, and that is precisely what Descartes suggested. The dualism of mind and matter suggested that there were two radically different kinds of realities, each sufficient in itself, and each requiring a different methodology with different assumptions.

Dualists are fond of a belief in immortality. If there is another type of reality besides the body, this non-body can survive death. The non-body can conceivably exist eternally in a non-physical world, enjoying non-physical pleasures or pains distributed by a non-physical God. This notion seems to be non-sense, but it apparently gives many people great comfort and hope.

Some dualists are fond of drawing a significant inference from the fact that we use different kinds of language to talk about physical things and non-physical things. They note that when we talk about physical things we use language that locates or causally connects objects in space. When we talk about processes such as thinking, however, we don't use the language of things in space. We don't think of thinking as taking place in a particular place or of a thought as having physical dimensions. That is true; however, dualists infer from this fact about language that the non-physical is a substance, i.e., a type of reality capable of independent existence, not reducible to some other phenomenon. Most dualists would agree that colors, for example, are not substances because colors do not have independent existence: they are reducible to other phenomena, such as light, sensory apparatus, etc. Yet, many dualists would deny that thinking, perceiving, willing, desiring, etc., are reducible to material processes (e.g., brain states). They believe these psychological or mental activities are best explained as functions of a non-physical substance. They can certainly be coherently explained by dualism, but it is not necessary to bring in the belief in non-physical reality to explain everything that is hard to talk about physically.(Author not available, DUALISM., The Columbia Encyclopedia, Seventh Edition, 01-01-2002.)

There are still materialists who deny the existence of consciousness as a distinct...

The crucial distinction now is as between weak dualists or 'epiphenomenalists' who regard consciousness as no more than the subjective reflection of what is going on in the brain and strong or radical dualists who regard it as a function of mind and as a having a controlling influence on what goes on in the brain.
As with most longstanding philosophical controversies, it is not easy to see how this argument can ever be resolved. Nevertheless, weak dualists may appeal to the notable progress in brain science following such technological innovations as brain scans etc. Once we know enough about how the brain works, they say, there will be no further need to invoke such intangible entities as mind or consciousness. Strong dualists, for their part, ask why consciousness ever entered the evolutionary process in the first place if it did not contribute to survival. Why could we not just as well have evolved as insentient automata? (In that case the present controversy over consciousness would still be debated overtly but, of course, no one would ever be aware of what was being said or written!)

Dennett, D, (1987)'Three kinds of intentional psychology', in The Intentional Stance, MIT Press, Cambridge Mass., 43-68.)

An attempt to give empirical support to the strong dualist position comes from parapsychology. Since there are, as yet, no accepted physical explanations for such phenomena as telepathy, clairvoyance psychokinesis etc. ('psi phenomena' as the parapsychologists call them) weak dualists are compelled either to deny or disregard the reality of such phenomena or else try to save face by issuing promissory notes affirming that all such phenomena will be explained physically in the fullness of time.

Modern Physical Science rejects the concept of Dualism. To show that the mind is nonphysical, we need to know not only what being mental amounts to, but also what it is to be physical. Descartes relied on the alleged indivisibility of mind, and on a conception of the physical as divisible. That conception of physical reality, in turn, rested on Descartes's conviction that the essential properties of physical reality are all geometrical properties. But there is another conception of physical reality that seems to support dualism. Scientific developments over the last four centuries present a picture on which the laws governing physical reality are invariably formulated in strict mathematical terms. (Watson, J.B. (1913): 'Psychology as the behaviorist views it', Psychological Review, vol. 20, 158-77)

This idea captures the mathematical character of the physical in terms that are more general than Descartes's claim that the essential properties of physical reality are all geometrical. So it allows for a less constrained argument for dualism, independently of particular claims about what's essential to the mind. Whatever the nature of thinking, sensing, desiring, and feeling, one might well deny that there could be strictly mathematical laws that govern such states. On this conception of the physical, then, mental states wouldn't be physical.

The argument as just formulated supports property dualism, on which no mental states or properties are physical. But we can adjust the argument to support substance dualism as well. If mental substances exist, their behavior would presumably not be governed by mathematically formulable laws; so such substances would not be physical. The argument is therefore more flexible than Descartes's appeal to indivisibility, which adapts less readily to the case of property dualism. This is important, since contemporary concern about dualism is almost always about dualism of properties, not substances. Partly that's because of doubts about whether the traditional notion of a substance is useful. But it's also partly from a tendency to think of people's minds not as any kind of substance at all, but rather as the totality of their mental functioning, including their dispositions and abilities to function mentally. (Feigl, H. (1958)'The "mental" and the "physical," in H. Feigl, M. Scriven and G. Maxwell, (eds) Concepts, Theories and the Mind-Body Problem: Minnesota Studies in the Philosophy of Science, vol. 2, Minnesota University Press, Minneapolis, 370-497.)

There are various reasons to think that mental states cannot be the subjects of mathematically formulable laws. We describe our thoughts and desires in terms of the objects they are about. The property of being about something, and related properties, are called intentional properties. Mental states can be about things that don't exist; we all sometimes think about and desire nonexistent things. So thinking and desiring are somewhat like relations one can bear to nonexistent objects.…