Idealism takes the three component theory of indirect realism, and removes the final component – the physical world. We are left with the perceiving mind, and the percept. The idealist, therefore, believes in a world of sense data, but, because we lack an indubitable knowledge concerning the existence of the world, cannot claim to know of the existence of the physical world.
As I have mentioned earlier, this belief seems completely against our notion of common sense. Why, for instance, would I doubt that this desk, or this computer, is real? When I touch it, it appears to have physical presence. When I look at it, it appears to take up space, and is clearly of a certain colour. Why should I doubt that these things exist outside of my mind? The counter-intuitive aspect of the idealist argument appears to be the biggest stumbling block the theory is facing.
Berkley, a British philosopher and subscriber to the idealist school of thought, put forward the theory that we can not imagine something that is not purely mental, because the process of imagining is mental itself. An idealist argues that in order for something to exist, it must be perceived. Because perception is a mental event, the object being perceived must also be a mental event. Therefore, the denial of an external world is not denied. It is theorised that the world does exist, but as a series of mental events.
To return to Berkley’s point. Dr. Johnson, a writer, attempted to present a counter argument to Berkley’s point. He kicked a stone, with Berkley watching, and stated ‘I refute thee thus’. He appeared to think that simply by kicking the stone, he would prove it had physical substance, as well as being a mental event in itself. He believed that if Berkley witnessed this apparently physical event, his argument would be quashed. This argument, however, was not sufficient to refute Berkley’s argument. In an idealist world, the stone that Dr. Johnson kicked was just a piece of sense data, as was Berkley, who witnessed the event occurring.
One problem an idealist may come up against is the fact that it is very hard to justify any beliefs if there is no foundation upon which you build your knowledge. The rationalist can always look at the ‘cogito’, and a realist may look at the very notion of sensory experiences. An idealist, however, lives in a purely mental world, in which no direct experience of the world can ever be obtained. This means that the only manner in which an idealist can attempt to justify their beliefs is through the coherence theory of justification. That is, a belief can be held to be true if it fits in with more beliefs than it contradicts. For example, I may believe that the British flag contains the colour green. If I consider that every time I have seen the British flag in the past it has not contained the colour green, and that my friend tells me the flag has no green in it, I see that this belief is not coherent with my other beliefs regarding the colours contained in the British flag.
We may argue that the very notion of coherent beliefs is, in its essence, a circular argument. We must depend on beliefs for which we can have no direct evidence, in order to justify beliefs that themselves have no direct evidence. It is this point that particularly troubles me with regards to the system of thought known as Idealism. Also, idealism appears to be in complete contradiction with my common sense view of the world. I must admit, however, that I find the arguments on the side of idealism hugely compelling, and for that reason, I don not feel I can personally deny the possibility that I am living in a purely mental state.
