It is said that one learns something new each day. At a young age one learns the basics of mathematics, speaking, writing etc. Nevertheless, how does one learn what a tree is, what it looks like, the color, smell, shape? One might learn that a tree is part of the Spermatophyte division, or that I its leaves are green and contain chlorophyll and even that paper can be made from it, but how does one know? One can touch the bark, see the leaves in the wind and even read about other's experiences with trees, therefore leaving knowledge that it is a tree. However, John Locke has much to add to this notion. Although it may be evident that the perceptual knowledge of external objects can be gai ...view middle of the document...
A tree in the external world causes an idea, and this idea, not the tree itself, is what is perceived. Furthermore, Locke tells us that there is a crucial difference between two kinds of simple ideas we receive from sensation. Some of the ideas we receive resemble their causes out in the world, while others do not. The ideas which resemble their causes are the ideas of primary qualities: texture, number, size, shape, motion. The ideas which do not resemble their causes are the ideas of secondary qualities: color, sound, taste, and odor. Locke argues that the ideas of primary qualities of bodies are resemblances of them, and their patterns do really exist in the bodies themselves. He then describes a grain of wheat. He argues that if the grain was divided into two parts each part would still have its primary qualities: solidity, extension, figure, etc. Locke argues that if it is divided once again it will still keep these qualities and if divided from that the same qualities will be evident. However, for secondary qualities, Locke argues that ideas produced in us by these secondary qualities have no resemblance of them at all. Sensations of color, odor, taste, and sound are caused by the powers of primary qualities to create the ideas in us. Given that we are able to explain everything we need to explain by positing the existence only of primary qualities, he reasons, we have no reason to think that secondary qualities have any real basis in the world. He considers an almond that is being pounded with a pestle. As it gets broken up into smaller and smaller pieces, the color changes from a pure white to a dirtier hue and the taste go from sweet to oily. Yet all that was altered was the texture of the nut. Clearly, he concludes, the secondary qualities depend on the primary qualities. Finally, he takes the example of a flame. If we put our hand in the flame we have a sensation of pain. If we look at the flame we have a sensation...
