Berkeley’s Subjective Idealism or Theory of the Existence of Things and Berkeley’s Criticism of Locke’s philosophy

Berkeley, the second in the line of the British empiricism,  is the founder of subjective idealism. Subjective idealism is an epistemological position according to which knowledge consists of ideas and ideas cannot exist apart from a mind. So, there is no extra mental objective reality existing independently of mind. Berkeley, who built his philosophic position following Locke’s empiricism, differs from Locke in a number of ways. He specially rejects Locke’s concept of substance and the primary qualities.                   
Though Berkeley uses the empiricism of Locke to establish his position, he is far from following Locke’s common sense approach concerning the existence of substance. Berkeley sets out to remove some of the rubbishes from Locke’s philosophy. Berkeley denies the existence of substance and the division between the primary qualities and the secondary qualities.

Berkeley introduces subjective idealism by his startling and provocative formula that “to be is to be perceived”, anything must be perceived in order to exist. Clearly this would mean that if something were not perceived, it would not exist. It was Locke’s philosophy that had raised doubt in Berkeley’s minds about the independent existence of things or matters that Locke sought as the source of sensory stimuli.  Locke had failed to push his own theory of knowledge to conclusions that to Berkeley seemed inevitable.                  

When Locke spoke of substance as “something we know not what”, he was only a short step from saying that it was nothing, which Berkeley did say. He denied the existence of the material substances and said that minds and their ideas alone are real. Berkeley says ‘Esse est percipi’. It means anything must be perceived in order to exist, no matter, but only qualities are perceived and therefore there is nothing besides minds and their ideas. What, for example is a cherry? It is soft, round, red, wet and fragrant. All these qualities are ideas in the mind that the cherry has the power to produce through the senses. So, that the softness is felt, the color is seen, the roundness is felt or seen, the sweetness is tested and fragrance smelled. Again, the very existence of all these qualities consists in their being perceived. And apart from these qualities there is no sensed quality. The cherry, then, represents a complex of sensation.

How Berkeley refutes Locke’s primary qualities

Primary Qualities: Berkeley refutes Locke’s theory of primary qualities and the division between the primary and secondary qualities. Berkeley, like Locke, had shown that the secondary qualities such as color, heat, round, taste, smell etc; are subjective. To a jaundiced person everything appears to be yellow. The same water appears cold or Luke-warm with the variation of conditions. He then proceeds to show that the lot of primary qualities is no better. Firstly, primary qualities such as extension, weight, motion, number etc vary with varying conditions like the secondary qualities. The same thing looks larger when we are near of it than when we are far off. The same motion appears fast to one and slow to other. The same thing is one, thirty six or three accordingly as it measured by a yard, a foot or an inch. Secondly, the proven and secondary qualities can’t be perceived apart from each other. So, extension can’t be perceived apart from color (by right) or heat and cold (by touch). The same arguments which make the secondary qualities subjective are equally applicable to the primary qualities. Is it possible, Berkeley asks, to separate primary and secondary qualities “even in thought”?   

Berkeley adds, I might as easily divide between primary and secondary qualities. But in truth the object and the sensation are the same thing and cannot therefore, be abstracted from each other. Since substance or matter is never perceived or sensed, it cannot be said to exist.

Berkeley was perfectly aware of the potential nonsense involved in his idealistic hypothesis. Aware that his idealism would be ridiculed , Berkeley writes what therefore becomes of the sun, moon and stars? What must we thing of houses, rivers, mountains, trees, stones nay even of our own bodies? Are all these so many chimeras and illusions of fancy?

According to him, objects are not therefore unreal. They exist primarily in the mind of God; and our ideas of them are only the reproductions of divine ideas. The laws of nature are the ways in which God perceived these ideas and reproduced them in finite spirits.

Berkeley adds: I do not argue against the existence of any one thing that we can apprehend either by sense or reflection.  The only thing whose existence we deny is that which philosophers call matter or corporal substance. And in doing of this, there is no damage done to rest of mankind, who, I dare say, will never miss it, says Berkeley.

In conclusion, we can say that in Berkeley’s theory a thing is the sum of its perceived qualities and it is for this reason he argued that to be is to be perceived, anything must be perceived in order to exist. Since substance or matter is never perceived, it cannot be said to exist. If substance does not exist and if sensed qualities alone are real then only thinking as Berkeley says, spiritual beings exist.