Secondly, the viability of Cartesian dualism has been reduced through philosophical examination. As mentioned previously, the problem which arises from the Cartesian conception of mind is how something spatial can interact with something supposedly non-spatial. This problem of interaction illuminates the flawed logic of the Cartesian conception of mind. The same category of logic has been used to specify the qualities of both mind and body, even though the dualist says that they are distinct entities. Being distinct entities they require distinct categories of logic for definitive purposes. From this application of the same category of logic to both the mind and the body, the result was as Ryle points out a 'category error'; dualist's descriptions of the mind were mere negatives of the specific descriptions given to the bodies; they are not in space, they are not modifications of matter, they are not accessible to public observation. If one keeps this category of logic constant when assessing the characteristics of the mind, one will find that the dualist's theory of mind is false in principle. For instance, if bodies cannot help the modifications that they undergo, then by using the same logic minds cannot help pursuing the careers fixed for them. This is obviously incorrect since responsibility, choice, merit and demerit are applicable concepts to the mind. From this it can be derived that the properties given to the mind by the dualist are wrong due to a 'category error', and that therefore the Cartesian conception of mind has been shown false.
Thirdly, while Descartes attempted to resolve this problem of interaction by suggesting a point of interaction between the mind and the body, further philosophical examination has dismissed his suggestion. Descartes suggested that the mind interacts with the body through the pineal gland. However, the pineal gland itself is a physical organ and hence the problem still remains: how something spatial can interact with something supposedly non-spatial.
Fourthly, one must establish science's credibility over other authorities to attribute it superior status with regard to the mind-body problem. The philosopher David Armstrong writes 'It is only as a result of scientific investigation that we ever seem to reach an intellectual consensus about controversial matters.' Before Copernicus, Galileo and Harvey, “there was nothing certain in natural philosophy.” During the 17th century the notion of an intellectual consensus regarding disputed questions was a seldom happening. There was no falsifiable method to investigate complex phenomena and therefore the possibility of confidently establishing one's doctrine was almost always a problematic one. However, the emergence of the scientific method has allowed for such concreteness and should thus be directed towards providing an alternate conception of mind to the Cartesian conception.
Fifthly, having now established the credibility of science over any other authority it is necessary to outline the current progress of science in providing an alternate conception of mind. Churchland explains that the explanatory resources available to the neurosciences are very well established. It has explained the microstructure, chemistry and physics of the brain. It has established correlations between damage to various parts of the brain, and various behavioural and cognitive deficits for which the victims suffer. If one compares this with what the dualist can tell us about the spiritual substance, one will become aware of the explanatory impotence of the Cartesian approach to mind. The dualist cannot tell us anything about the internal constitution of mind-stuff nor the mind's structural connection to the body. In addition, science has demonstrated the possibility that physical matter does not have to be spatially located, as Descartes stipulated. For example, as Churchland points out, science has discovered that the electron – a physical phenomena – has no spatial extension. This suggests that physical matter does not have to be spatially located to exist as physical matter, and thus challenges the viability of the Cartesian conception of mind; the dualist may be right when saying that the mind is not spatially located, but with reference to the electron example, being without a spatial location does not mean that it is of spiritual quality.
Sixthly, the viability of the Cartesian conception of mind has been reduced through the introduction of alternate conceptions of mind with comparably more explanatory power. The philosopher D. Armstrong has suggested an alternate conception of mind consistent with the physico-chemical view of man. He suggests that a mental state is a cause within a person apt for producing certain ranges of behaviour. Now, if these mental states are products of the central nervous system a purely physicalist account of mind can be validated. There is evidence which lends support to this conception of mind. Neural dependence demonstrates how vulnerable reason, emotion and consciousness are to pathology. Alcohol, narcotics, or senile degeneration of nerve tissue will impair, cripple, or even destroy one's capacity for logical thought. Ecstasy alters levels of serotonin in the brain, resulting in extremely happy emotions; a clear example of how something physical can affect mental states and processes. While this physico-chemical view of mind seems plausible, many continue to reject it because when one introspects one does not simply comprehend physical processes at work, one thinks of thoughts as non-physical workings. When one introspects they “apprehend a flux of thoughts, sensations, desires and emotion... different from physical states and properties”. However, human resistance to a purely physico-chemical view of mind is understandable; being reduced to a simple physical product leaves man with little spiritual faith, as he no longer retains any spiritual side. While the physico-chemical view of man has not been confirmed, it has comparably more explanatory power than the Cartesian conception of mind, resulting in a reduction in the viability of the Cartesian approach to mind.
Over three hundred years have past since the Cartesian conception of mind was formulated. Since then, no one has been able to solve the problem of interaction it entails. This historical failure coupled with revealings of a 'category-error' by philosophic inspection and the introduction of alternate conceptions of mind based on the concreteness of scientific study have certainly reduced the viability of the Cartesian approach to mind. Whether a scientific alternative will ever be formulated is unknown, however, what is sure, is that granting its unique ability to achieve intellectual consensus it is the authority which has the most potential over any other to secure an alternate conception of mind.
Hobbes quoted by Armstrong, p.43
