The Human Brain and Sensations

“Sensations and Brain Processes” was published 58 years ago. J. J. C. Smart’s iconic work was published. This paper examines Smart’s work in order to assess how it has progressed over time and the effect it has had on the growth of philosophical ideas. The paper focuses on Smart’s theory that sensations are brain functions, as well as the relationship between the thesis and the objection of indistinguishability of similar objects. The paper includes a lengthy discussion of this specific objection as well as Smart’s response in support of the thesis proposition. Smart argued that stimuli are in fact brain functions. Smart argued that sensations are indeed processes of the brain. He held a strong belief that it is illogical for states of consciousness and sensations not to be brain processes the same way as other chemical and physical mechanism are. His stand is seen in his arguments and his defense for the thesis proposal. The paper goes ahead to explain how Smart’s theory can be applied to explain the issue of optical illusion.

The Objection of Indiscernible identical objects

A possible objection to the thesis proposal made by Smart that sensations are brain processes could be; no part of the brain is red, yet some sensations are red. Because by indiscernibility of identicals, two similar objects must have their properties being similar therefore sensations are not brain processes.

This objection holds that if two situations say A and B both refer to one same entity then when a predicate of A forms a true proposition then the same true proposition must be formed by a predicate of B. The meaning here is that if all predicates taken to be true for A happen to be true for an entity B and if all predicates true for B are considered to be true for A then A and B are probably one and not two things. When applied to the brain processes and the case of experiences the meaning of this concept is that if a brain process were to be discovered having all the characteristics that the introspecting subject attributed to the experiences of the current times and with no features which the subject was composed to admit as being verifiable of the current experience, it could be possible to conclude that brain processes and experience are one thing. In reality and practical terms, however, there has never existed such a brain process.

Smart’s response to the objection of identical indiscernible objects

Smart’s response to this objection incorporated the technique that reiterated the fact that physical terms and mental terms have different meanings. Smart also added that these two concepts do not have the same logic. He asks us to differentiate between mental state or experiential states and mental objects. He doesn’t propose that the mental object which he refers to as the after image be identified with any processes of the brain. Rather he defines the nature that experiences an after image that is orangish with some processes of the brain, thus overruling the objection. It is true that the processes of the brain occur inside the brain somewhere and is not orangish. The similar condition happens with pain. When one’s body part pains, the state of pain isn’t in that particular body part. It is that particular state and not necessarily the mental object that the identity theorist tries to identify with the brain state. What then would an identity theorist say about the pains and the after images themselves? Many theorists of the identity concept would mean that there are no objects that exist that the words pain and “after-image” and “pain” refer to. Some people find themselves in a given state, the condition called “being in pain,” but pains, as specific objects are not there thus things, are not their after-images. But, saying that there’s an after-image or you have an after image in mind is like talking about the kind of state of experience one finds themselves in. You, therefore, find yourself in a state of experience that represents some ball of light that glows with the color orange. Such experiences serve merely things that are nonexistent. The same way the Identity Theorist will propose that such elements as pain don’t exist. Pain talks are misleading ways of speaking about conditions that feel sorry (Smart, 1959).

The color of sensations according to Smart

In explaining the issue of color concerning sensations, Smart introduces the subject percipient. He says that a person is considered a normal percipient compared to another if he can make the discriminations of color that the other person cannot. An example is issued about a person A, who can pick a leaf of lettuce out of a heap of leaves of cabbages when person B cannot though he can choose a sheet of lettuce from beetroots. So A is considered more normal than person B, the analogy is presumed to be in the assumption that all of them are not given the opportunity to differentiate leaves earlier on according to their slight differences. By saying that a given color is red the meaning is that a person who is normal would pick it with difficulty out of geranium petals clumps though he would separate it from leaves of lettuces. Regarding, of course, does not mean that a person may know the meaning or red without knowing about normal percipients or even geraniums. But the truth is that an individual can be trained to say this is “red” regarding objects that would not be easily picked from a clump of geranium petals by a percipient that is normal. This means that even someone who is color blind can assert reasonably that a given thing is red even though he may need to use somebody else. Thus secondary characteristics account as such are not important in physics, for reasons that the lack of discrimination or the discrimination made by a sophisticated neurophysiologic technique are not likely to correspond to non arbitrary and straightforward distinction in nature. Thus Smart explains precisely colors to power in the sense of Locke, to be able to arouse kinds of responses that are discriminatory in humans. And they are also sensational powers in humans. Though the sensations are identifiable with processes of the brain as Smart argues. Therefore the sensations can be neutral between materialistic metaphysics and dualistic metaphysics. This explains how the brain processes can be the sensations, but the reporters may not need to know anything about the processes of the brain because they report them abstractly, therefore creating some raw feelings .The reason why no one can put proper characteristics on them. In the View of Smart raw feelings are colorless for similar reasons that something may not have color. However Smart goes ahead to state that by being the processes of the brain, sensations do have properties. Thus the point is that when speaking of the sensation to be like or unlike one another we need to mention or know these features. Smart defies arguing that the after-image is a process of the brain. But the experience that comes with the possession of the after an image is the process of the brain. Thus according to smart sensations are not red and the color and the physical characteristics of sensations regarding colors is not reasonable thus they have no colors (Smart, 1959).

Smarts response to the objection of sensations and physical space

Another objection to the thesis that sensations are brain processes states that sensations are not in physical space but all brain processes are in physical space. Smart refers to this argument as an ignoratio elenchi. He says that his argument is not that sensations are a process of the brain but that the experience of having sensations is a process of the brain. The experience is what is reported in the introspective report. The same way that if it can be objected that a sensation is yellowy-orange, but the brain has no part being yellowy orange Smart replies that it is the experience of seeing an image that is yellowy orange that is being described but that particular experience is not colored in any way. Thus by saying that a process of the brain cannot be colored is not saying that the processes of the brain cannot be the experience of having sensations that are colored. In real sense, there is no such thing as a sense datum or a sensation though there exist certain things as having experienced an image and that particular experience is indirectly described in a language that materially objects but not in a language that is phenomenal because such things don’t exist. The experience is outlined in effect by saying that it is the same experience we go through when for example we see a colored patch on the wall. Objects can be colored but not the experience of seeing the objects or imagining them, or if in any case they are described as being colored then this can only be done in a sense that is derived (Smart, 1959).

Response strategies on the objection that brain processes and sensations have different properties

Smart’s response to the above objection is that he never claimed that the processes of the brain and brain processes and experiences have the same logic or even mean the same thing. The word “doctor” and the word “somebody” do not reflect the same thing. When an ordinary person reports something, he does so by saying that something is going on but does not explain what sort of stuff is going on by that just leaving it open. All that Smart was referring to was that brain processes and experiences might be referring to the same thing thus if that is so then a convention may quickly be adopted where talking of experience as processes that are physically appropriate would be sensible.

Smarts theory and optical illusion

When an object appears smaller from a far away distance or bigger when nearer what happens is that the visual system goes through an optical illusion. The images observed through visual illusions are perceived as different from the actual object regarding color, size, shape, position, movement and tilt. The information from the eye which is gathered in the form of visual stimulus is processed in by the brain to create a visual perception that appears different with the actual object regarding size color and so on (Coren,1978).

This is as a result of physiological illusion which is caused by adapting or bright stimuli alternating patterns that are excessively longer. The more long experience causes the stimuli to compete for a given characteristic of the real object say shape or size. The explanation behind the theory is that a stimulus has to follow its dedicated individual neural path during the initial stages of visual processing thus the repetitive activity or great notion or the communication with adjoining active channels leads to a physiological imbalance which makes the perception to be altered. In the biological concept, the Mach bands and Grid illusions are real examples that are well explained. Lateral inhibitions of the retinal light in the receptive fields compete with the dark receptors for activity. Thus bands of increased brightness are seen when viewing each band at the edge of a color difference. When a receptor becomes active adjacent receptors are inhibited highlighting edges and as a result creating contrast (Coren, 1978).

An after image is also a type of optical illusion in the sense of Smarts explanations. An illusion just like after images is evidence that people don’t always see what they think they do. According to Smart, concrete terms and mental terms have different meanings and the two do not represent the same logic. What people see is the experience that they have acquired over time, and when people report the experience, they find themselves communicating things that are nonexistent. But the experience is a brain process thus there is the possibility of the brain processing certain phenomena that are nonexistent. Just like the optical illusion the things seen may not be real, for instance, an object may appear smaller from a far away distance but larger when nearer. Visual illusions are brain process do are afterimages. Therefore Smarts theory can be used to explain the phenomena where images appear to mismatch the actual objects. The images can be said to be an impression that is created immediately to replace the actual characteristics of the object. In the same note after images are incorrect and do occur as a result of long time interactions with the particular objects.

Everything that is absorbed by the senses has to be interpreted by the brain but sometimes these interpretations are wrongly processed leading to the wrong perception of images a phenomenon that is called visual illusions. If the brain can incorrectly interpret optical illusions so can after pictures. The subjective perception of people sometimes can mismatch the physical reality that exists in the world just like Smart says that when one claims to see a yellow-orange patch on the wall might not be true but it is the experience of that particular individual of seeing such an image that could be driving them to make such claims. This therefore shows how smarts theory can be used to explain why objects appear smaller from a distance and even bigger when nearer. An optical illusion is an indication that some properties of the eye might be the ones leading to the mismatch between the image and the actual object, the same way that after images do occur as a result of experience and not that the object really has the particular characteristics as perceived in the brain (Coren,1978).

According to Smart when people report irreducibly physical objects then they are experiencing after images. But the condition is a mental process. But it has been justified that when our eyes get exposed to certain things for long, the cons and rods become fatigued making someone to see the complement or the inverse of the image when they look at a different direction, making one to see a contrast to size, color, shape and other secondary characteristics that an image has.


Smart’s theory gives a detailed account to explain why an object may appear bigger or smaller with changes in visual distance. The theory provides an insight into understanding this phenomenon. According to the explanations given by Smart we can deduce that after images usually vary in secondary characteristics in comparison with the actual objects. The illusion created makes an object to be perceived as bigger or smaller when viewed at varied distances and angles.


Coren, S., & Girgus, J. S. (1978). Seeing is deceiving: The psychology of visual illusions (p. 214). Hillsdale, NJ: Lawrence Erlbaum Associates.

Smart, J. J. (1959). Sensations and brain processes. The Philosophical Review, 141-156.

Deadline is approaching?

Wait no more. Let us write you an essay from scratch

Receive Paper In 3 Hours
Calculate the Price
275 words
First order 10%
Total Price:
$10.99 $35.97
Calculating ellipsis
Hire an expert
This discount is valid only for orders of new customer and with the total more than 25$
This sample could have been used by your fellow student... Get your own unique essay on any topic and submit it by the deadline.

Find Out the Cost of Your Paper

Get Price