Smart contends that sensory statements which seem to correspond with brain states such as, “I am in pain,” or, “There appears to me the visual sensation of a yellowish orange after-image,” can not be reduced to reports as those which refer to a uniquely mental substance. Instead, they seem to be composed simply of physical processes, subject to all the same natural laws as those which describe the body. He argues by Occam’s Razor that the fields of science offer increasingly sufficient explanations for the natural world composed solely of physical constituents, and that these too should be applied to the human mind, rather than reserving it as some special class of entity entirely distinct from the rest of the world made up of extended body. In this way, it does not even seem to begin to make sense to correlate these as separate, but mysteriously interrelated processes, as we come ever closer to a single physical description of sensations as brain states. Such correlations between entities with themselves fallaciously infer something outside of this identical thing to begin with. Instead it seems more reasonable that consciousness not be the lone entity left out of the physicalist description of the world.
The primary objective of this program was to dispel widely held and ill-established beliefs which commonly can be condensed to some idea of a distinct and separate existence between the mind and body. Rather, Smart hopes to reduce the purely mental sensations which follow to facts referring to probabilistic statements according to physical brain states. In this way, the exclamation, “I have a yellow-orange after image,” does not report on a correlation between the mind and body, as it is instead simply composed of the outcome of the temptation to assert the presence of a corresponding physical patch in the world. If there is a report of anything at all to be made then, it can not be of a mental substance, or the subsequent result of the physical temptation, but only the causal brain process itself. Although these statements happen to be of brain processes, this is not to suggest that the logic of sensation statements is similar or even directly translatable into those of brain statements. Many people, including the young and uneducated, seem quite capable of forming sensation statements despite having no conception of brain processes and therefore their underlying identity.
Despite these possible differences in systems of logic, this does not strictly rule out that these are still equivalent to one another. This can be seen by the often direct translatability of reference between languages, even if one happens to be generally unaware of the meaning behind the identical words in the great majority of languages which they do not happen to understand. This seems to allow for forming contingent implications of the form, “A is identical with B,” even if one were to “only know A and not B,” as in the case of making sensation statements all the while being mostly ignorant of the deep physical laws which underlie these brain processes. And although someone may speak solely in terms of such sensation statements, these should not then be mistaken for being the brain processes which are their cause. As though such a person clearly can not mean to refer to brain processes in making a statement in ignorance of them, this does not strictly entail that they are not still one in the same thing. In this way, people often speak of natural occurrences in the world in a casual manner, without having a firm scientific understanding of the underlying physical laws, even though we would like to maintain that these are true descriptions of such phenomena.
Many empirical claims are well-established even if direct observation is infeasible, as in the case of the inferred chemical compositions of incredibly distant stars based on data collected through experiments founded on the physical laws. Although it seems highly probable that these observations are accurate, it could never be directly tested even if such distances were overcome, as no physical instrument could survive on the surface of a star. In the same way, it is possible to come to be quite certain of inferences as to others’ mental states, despite direct observation seeming impossible and therefore never being able to be completely convinced of these external processes. It is subject only to the same exact consequences we hold of any other inductive affair, including all the rest of the physical laws themselves. We make our best accommodation for this problem through our criteria as to the exact details behind the mental states of others, which are probabilistic in the same way that medical diagnoses of our physical bodies are. This lack of complete certainty does not suddenly entail either body of knowledge as rendered entirely obsolete, but only subject to the same scrutiny which any other field of science is forever held under consideration. In the same way, we discovered that “water is H2O,” through a process of such significant and enduring scientific investigation that it seems doubtful this claim will ever come to be refuted, despite the fact that we will never be able to come into contact with such a minute entity directly.
According to Ryle, Dualism primarily entails that, “Every human being is both a body and a mind.” Whereas the body occupies space and is subject to all the physical laws, the mind is not at all extended in space or subject to any of the physical laws. In this way, it can never be experienced by other observers in the way that external bodies can directly interact with one another. Every person lives out two separate histories, that of the body’s which is open to outside observation, and that of one’s own mind, which is not. It has not been well-described how these two seemingly fundamentally distinct processes interact. There is also seemingly no reason as to why two entirely separate, but some how causally-related, forms of existence should arise. However, we form conceptions of the mental processes held privately by other minds very easily and often, and so it seems there must be a better description that allows for such intricate inference in to what Dualism holds as being an entirely internal and inaccessible phenomenon from the outside. Smart’s view contends instead that mental states are identical with brain states, which reduces consciousness to a physical description in line with all other apparent laws. Dualism is founded on a category mistake, in that it maintains the mind and body are both unique substances, but of similar type. Instead, just as the body is characterized by numerous interrelated physical processes, such as chemistry, physics, and physiology, so too must the mind be thought of in terms of such complex and interrelated abstractions of nature, rather than as a simple, solitary substance.
Behaviorism in its most basic form suggests that there are mental statements which directly entail certain behavior statements they are disposed toward. It seems unlikely; however, that a program to correspond all mental-statements with physical behaviors through any sort of direct translation will be successful, although such translations are at least possible also does not seem to be refutable. Instead, we must accept that such entailments can instead be constructed through the ambiguity of mental state as compared with the clarity of overt actions. In this way, mental states can be seen to entail dispositions toward behaving in certain ways, and we are able to infer the mental states of others by correlating their common behaviors with our own. Smart’s view holds instead that mental states are equivalent with brain states, and so it is wrong to identify them with the end result behaviors, or attempt to correlate the underlying brain states with themselves.
Putnam criticizes Physicalism as to its inability to relate separately held behaviors in the way we can things such as patches of color. It’s not that diseases cant’ be translated into symptoms because diseases are ambiguous whereas symptoms are more specific, but that generally causes can not be logically constructed from their effects. In this way, it does not in the least begin to make sense to construct mental states out of physical behaviors, even if done through careful probabilities. While we are cultured toward pain instigating certain responses such as wincing, or crying, it would be wrong to suggest any behavior at all is entailed by experiencing pain. It seems likely that Martians or even other species on earth, many which maintain vastly different neurological structures from our own, could very easily experience pains without exhibiting any of the same responses which we happen to be disposed toward. And though one might be inclined to list out these brain states which correspond with the exhibition of pain in each species, it seems at least credible yet that one could experience a pain and not shed even the slightest report of it. In this way, we would be wrongfully led to suggest they do not feel pain at all.
This multi-realizability of mental states must be able to be formulated by different sorts of physical brain processes and so we need a different account of the enduring similarities and shared experiences between minds. He instead argues that mental states, such as that of being in pain, are to be identified with their function on the organism, which might then remain the same despite overwhelming differences in physical configuration between the brains of each species. In this way, the mind is then described as a series of inputs and outputs, which can be viewed as a series of interrelated Turing Machines, which tend to hold within each capable organism. Multi-realizable mental states can then be very easily constructed out of unique sets of these inputs and outputs resulting in equivalent mental states for different configurations. Lastly, rather than the purely physical explanation offered for mental states by Smart, this view takes in to account that the field of psychology offers a complex psychical abstraction of the mind from nature.