Primary and Secondary Qualities of Bodies
By Paul Erekuff
This essay concerns John Locke’s thoughts on primary and secondary qualities, and the views that David Hume and George Berkeley have on these qualities. In the first section I will give Locke’s definition of primary and secondary qualities and some examples he gives to demonstrate his views. I will also give the arguments that Locke believes supports these views of the qualities. Then I will show how Berkeley attacks Locke’s views of primary and secondary qualities. We will see the conclusions Berkeley gathers from his refutation of Locke’s view of primary and secondary qualities. Next I will show the way Hume attacks Locke’s view of primary and secondary qualities. We will see the conclusion Hume draws from his refutation of Locke’s view of primary and secondary qualities.
Primary qualities are those qualities in bodies that have no necessary relation to sensation. Locke believed that the primary qualities produced by objects resemble the objects themselves. These qualities are inseparable from the bodies themselves. They are solidity, extension, figure, and mobility. “ For division can never take away either solidity, extension, figure, or mobility from any body, but only makes two or more distinct separate masses of matter of which was but one before.” Although Locke never convincingly or dominantly defended his thoughts on primary qualities, he thought that the primary qualities resembled the objects that caused them because one could not be fooled or sense differently then exactly what the primary qualities are. For instance if I have the idea of a sphere or a square, the idea I have of either of these object’s primary qualities will be the same in both idea and in existence. “Figure never does that, never producing the idea of a square by one hand, which has the idea of a globe by the other.”
Secondary Qualities of objects do not exist in the objects themselves; instead they are the sensations that primary qualities have the power to produce in us. “The idea of secondary qualities are also produced, namely, by the operation of insensible particles on our senses.” Secondary qualities are qualities such as colors, sounds, tastes, smells, light, and heat etc. For instance, human beings feel heat from a fire because the bulk, figure, and motion i.e. primary qualities have the power to produce the idea of heat in our minds. One experiment used to illustrate the secondary qualities is pounding an almond. If a person were to pound an almond it would become dirty. The clear white color that the almond formally had would now be brown, and the former sweet taste of an almond would be oily. However, if the idea sweetness and whiteness were really apart of the almond pounding the almond would not change the taste or color. Instead it is the primary qualities of the almond that cause the certain tastes and colors we experience of the almond. Locke’s argument for secondary qualities is much stronger than his argument for primary qualities, but underlying both of these arguments its seems Locke makes those ideas which can’t be misconceived primary, and those which have the ability to fool people secondary qualities.
Berkeley attacks Locke’s view on primary and secondary qualities by extending the reasoning Locke uses to prove his own views on these two qualities. Although Locke never stated or defined it in his essay, when he proved his thoughts on primary and secondary qualities he used two senses of the word idea. He used it first as ideas, those being of the mind. These ideas I will call ideas-1. Then he uses idea to describe the ideas that are produced by ideas-1. These ideas I will call ideas-2. Locke then went on to claim the ideas-1 exist in the bodies themselves. This is where Berkeley interjects by stating that ideas-1 is mind-dependent and “that an idea can be like nothing but another idea”. Berkeley claims it is impossible for any idea to exist in an unperceiving thing because having an idea can only come from perceiving. Therefore anything that we perceive, any object independent of the mind, only exists within the idea-1 of itself. This is because it was only the idea-1 that was the cause or reason behind the perception of the object. Since mind-independent bodies depend on mind-dependent ideas, no physical objects truly exist. Therefore anything that Locke claimed about ideas existing in bodies is false, his ideas on qualities are wrong, and his philosophy falls apart.
Berkeley then moves on to Locke’s ideas concerning the secondary qualities. As previously stated secondary qualities depend or are caused by the power of primary qualities, and they can fool our sense. That is why with the same water, at the same time we can feel heat in one hand and cold in another, as shown by Locke. Berkeley asks why we cannot extend this argument to motion? He appeals to the fact that motion is not just in bodies, but also within the mind. “If the succession of ideas in the mind becomes swifter, the motion, it is acknowledged, shall appear slower without any alteration in any external object.” Are we not now fooled by the primary qualities of motion? Then what was the distinction between primary and secondary qualities now becomes the bond between them. Therefore secondary qualities are not powered into sensation by the primary qualities, but they too are mind-dependent.
As seen Berkeley’s main conclusion drawn from destroying Locke’s philosophy is the truth that no physical or mind-independent matter exist. Everything we perceive, through every medium of our senses exists only as ideas, and not as physical things.
Hume attacks Locke’s views on primary and secondary qualities by attacking the primary qualities, which are dependent on no other ideas, and asking how human beings perceive the ideas of primary qualities. In agreement with Locke, Hume concluded that we perceive primary qualities such as extension through our vision. Hume then goes on to question how our mind interprets vision, which he finds to be nothing but an array of colors. However, according to Locke colors are secondary qualities. How can something like extension which exists in bodies, be perceived by a quality that is not in the body? Hume next moves his attacks to the primary quality of mobility or motion. Hume states that motion can only be perceived if it makes reference to another body or idea, so therefore motion must be dependent on other qualities. “[Motion] must resolve itself into the idea of extension or of solidity and, consequently, the reality of motion depends upon that of these other qualities.” Since motion depends on another quality it cannot be a primary quality.
One by one Hume dismantles Locke’s ideas on primary qualities. Solidity claims Hume is incomprehensible alone, we cannot have an idea of solidity without first knowing the object is solid. But we cannot defer solidity to extension, motion, or any other sensible quality because we would have the later depending on the former, while at the same time having the former depend on the later. This “leaves us no just nor satisfactory idea of solidity nor, consequently, of matter”.
The conclusion Hume draws from his arguments on the qualities,