Sense Data is, according to the theory of Representative Realism, the medium through which we perceive the entire world. According to this theory, we can never perceive objects directly, as all we perceive is sense data. There are a number of arguments used to prove that w do only perceive sense data. One example is the argument from phenomenal variability, which is best explained by the example of Russell’s Table. Essentially, we look at a table, and it appears to us to be a table with certain properties. If we change the conditions under which we view the table, the properties of the table also appear to have changed. It may have changed colour, shape, or size, but it will not look the same as when we first viewed it. Russell states that, as it cannot be the object itself that changes, it must be some intermediary that does, namely sense data. This argument, however, is seriously flawed. If it is true that we can only gain knowledge of objects via their sense data, and we can have no direct knowledge of the object itself, then how does Russell propose to argue that the object is not changing shape? He quite clearly cannot know what the object itself is doing, and so can offer no empirical proof as to why the object may not change shape. He therefore has no grounds upon which to base the claim that the object does not change, and so the argument from phenomenal variability fails. Russell attempted to back up his variability argument with another, which centres on something happening, and it not becoming noticeable for a period of time. The most common form of this argument is the dead star argument. This simply says that, as light from the sun takes eight minutes to reach Earth, if the sun went out, and we all looked up, for another eight minutes we would still be able to see the sun. But we cannot be seeing the sun, as it is no longer there. Instead, we must be seeing sense data. This argument is also flawed, but in a less obvious way. This argument is attempting to state that we can have no direct knowledge of physical objects. This then makes any and all of our knowledge of physical objects doubtful, as it is not direct. As such, how can we be asked to consider an object, of which we effectively know naught, exploding? The argument relies on sense data representing the object to us, and yet makes an assumption that cannot be backed up by any form of evidence whatsoever, namely that the star exists, and then explodes. This argument fails because the grounds upon which it is based do not support the outcome. Because of these flaws, the Representative Realism Theory appears to be unusable. However, its competitors do not appear to fare so well, as we shall see. Realism is a theory which holds that we do perceive objects directly, there is no such thing as sense data, and what we see is how the world is. This theory, too, has some major flaws. Firstly, there are optical illusions. These show us things that are simply not true, and yet, we see them. For example, we may see water on a road on a hot day. However, were we to stop the car and get out, we would find the road dry. Or we may dip a straight stick under water, to see that it is bent. There is also the argument from physics which does considerable damage to the idea that we see the world as it really is. Realism defends itself from these ‘errors of perception’ by claiming that these errors only occur under certain conditions, and, whats more, we can replicate these conditions to replicate the error. It would seem that, because we know why the light bends, the theory is considered still valid. The argument from physics is simple. It states that, if science is an arbitrary and accurate account of the world, then there is no such thing as a solid object, all things are composite objects, and all things are constantly moving. These three statements are clearly at odds with the way that we see the world. Fortunately, for the realism argument, the argument from physics does not count against it, as the scientific definitions of ‘solid’, ‘composite’ and ‘moving’ differ slightly from the usual meanings of the words. This theory, whilst being fairly conclusive as to why it is not wrong, fails to persuade me, at least that it is right. I personally believe that the correct theory would be more of an over-arching theory, which works well with both normal and scientific definitions, as opposed to just brushing them off as ‘different’. The final theory of perception is idealism. This is where the nature of the universe is defined as mental, e.g all objects are essentially collections of ideas, and only exist for as long as they are perceived. Assuming that this is true, how can bread, in a period of non-existence (when it is shut inside the breadbin) sprout mould? For that matter, how can we perceive something that doesn’t exist, so as to bring it into existence? These are the obvious questions with which we can destroy this theory. But we have been given a reasonable excuse for the points in question. In the argument, it never specifies that it must be a human mind doing the perceiving. This is because, if we allow ourselves to believe that God is perceiving everything, as we know He can, Him being omnipresent, then that explains why the interiors of people’s houses don’t just wink out of existence when they go shopping, or why cars in garages don’t disappear at night. This does, unfortunately, leave the theory open to disaster, as we need independent proof of Gods existence before we can say He is what supports the entire Idealism theory. As we have no proof for or against God’s existence, we can neither disprove nor prove the theory of idealism. As none of the perceptual theories appear to have any flaws that are inexplicable, but have no points that mark them out as correct, it would appear to be a better idea to treat them all as ‘works in progress’, than as fully formed theories, and as such, none of them need be accepted as correct, as none of them are more likely than the others to be proven correct.