In this essay I am going to be examining some of the main claims made by indirect realism as well as looking at some of the fundamental problems these claims cause for the theory, such as the epistemological problem, the ontological problem, and the fact that the theory inevitably leads to solipsism.
Indirect realism first arose in an attempt to resolve some of the problems faced by common sense realism, where it became apparent that the assumption that our senses almost always give us true information about the nature of the external world is implausible.
Indirect realism therefore modifies the ideas presented by common sense realism, by suggesting that what we perceive directly and are immediately aware of is not the world or the objects within it, but sense data. Indirect realists are far from denying the existence of the physical world, but simply claim that the physical objects in the world cause our sense data, and that the sense data we experience represents the external world, to an extent. For example, when I see a horse, I do not perceive it directly, as common sense realism would suggest. I have no sensory contact with the horse, and what I am aware of is only a mental representation, sort of like an inner picture, of the horse. My visual experience is not directly of the horse; however indirect realism claims that it is caused by the horse. What I am aware of is the representation of the horse, which my senses produce.
As Dancy explains, Indirect Realism argues that “in perception people are indirectly aware of the physical worldaˆ¦in virtue of a direct awareness of internal, non physical objects.”  This means that although someone’s idea of an object may resemble the object itself, a person can only ever be aware of their idea and never the object itself.
Indirect realism also seems to provide a response to the objections to common sense realism, raised but the Illusion Argument. In the instance of colour, for example, one jacket can look completely different colours when viewed in different lights. If we were to then examine the fibres of the jacket material in more detail, we would probably find them to be a variety of different colours. The way it is perceived also depends on the viewer, for example, someone who is colour-blind may see the jacket differently to someone with full colour vision. In view of this, it doesn’t seem to make sense to say that the jacket is really yellow, or that its yellowness is independent of the perceiver. In an attempt to explain this kind of phenomenon, indirect realism introduces the notion of primary and secondary qualities.
Primary properties resemble the real properties of the object. John Locke, describes them as being “utterly inseparable from the body”  and necessary for conception of it. Primary qualities exist both in the world and in sense experiences, and can be experienced by more than one sense. They are measured by physics and are qualities which the object actually has, regardless of the conditions in which it is being perceived or whether it is being perceived at all. Primary qualities include shape, size, position solidity, extension, motion and rest, and number.
Locke argues that secondary qualities are “nothing in the objects themselves but powers to produce various sensations in us,”  and conceptually inessential. These qualities exist only in sense experiences and can only be experienced by one sense, but objects in the physical world have the power to produce these experiences in us. It may seem as though these properties are really in the objects we perceive, for example, that the yellowness is somehow part of the yellow jacket, however the yellowness that we experience is simply the object’s power to produce yellow images in a normal viewer, under normal conditions. The ideas we have of secondary qualities don’t resemble the actual objects but are simply a product of the kind of sensory system that we have. Secondary properties include colour, temperature, smell, taste and sound.
One major objection to indirect realism is that it seems to make the real world unknowable. It only makes sense for us to say that A resembles B, if it is possible for us to be directly aware of both A and B, in order for us to compare the two. This creates a rather fundamental epistemological problem for indirect realism because the theory states that our sense experiences of the primary qualities of objects resemble the actual qualities of objects in the external world, however, it also states that we can never be directly aware of the external world, so we therefore have no way of checking whether our sense experiences do in fact resemble the external world at all. For example, if my sense experience of a ball is round, I have no way to check that this corresponds with the actual shape of the ball in the external world. We are entirely limited to the evidence of our senses, and since these work by means of mental representations, it seems as though we can never gain any direct information about the actual properties of the ball, or any other object in the external world.
Indirect realism has also led to a problem related to what is known as the veil of perception, which refers to things that are seen indirectly, and not as they are in themselves. This is because there is a “veil” that we cannot penetrate, because the things that are being perceived (in this case, objects in the external world) exist independent of sensation. This creates a rather fundamental ontological problem for indirect realism, because it only seems to make sense to say that A is caused by B if it is possible for us to know what B is, however the veil of perception seems to prevent us from doing this. Since we are unable to directly access any physical objects in the external world, it is possible that our sense experience could be caused by something entirely different, for example, Descartes’ evil demon, God, a mad scientist, the matrix, or ourselves.
We have no way of getting ‘outside’ of our own perception to find out what is causing our sense experiences, if there is in fact anything causing them at all. This is another serious problem for indirect realism; it can lead to solipsism, which is the belief that nothing exists beyond oneself and one’s immediate experiences. It suggests that since we cannot know the external world and other minds directly, they may well not exist at all. Solipsism is argued to be philosophically absurd for two reasons; the first being the phenomenological reason, which claims that if we were the only beings that existed, we would not feel emotions such as shame, embarrassment and guilt, which require the existence of another person or being in order to have any effect. The second reason is that logically, solipsism just doesn’t seem to make sense, and therefore any theory that leads to or allows for this view point, the way indirect realism does, is also argued to be absurd.
In conclusion, it seems that although indirect realism does manage to overcome many of the problems faced by common sense realism, it also seems to create many more serious problems of its own. Although the theory at first seems quite plausible, the fact that it allows for solipsism makes it pretty much irredeemable. Indirect realism also fails to account for the causal relation between the external world and our sense experiences, and as we have seen through the veil of perception objection, we have no real reason to believe that our sense experience bare any resemblance to the external world at all. I think indirect realism would be much more plausible if it could offer some form of explanation of the interaction between our sense experiences and the external world.