John Locke's Distinction

Berkeley also articulates a second challenge to Locke’s distinction. Berkeley employs one of the proofs used by Locke to show that secondary qualities are mind-dependent to demonstrate that the same proof can be used to show that primary qualities are also mind-dependent. Locke observed that the same water can produce the idea of hot on one hand and cold on the other [perhaps one hand has been exposed to the cold for some time] (ECHU, II:8:21). The same water cannot possible contain both the idea of hot and cold at the same time, so the discrepancy must be due to our perception of it. Locke argues that we can perceive a change in the secondary qualities without the object itself changing, but that this does not happen with respect to primary

For example, imagine a book. From the side, the book may look rectangular. From above, the book will look rectangular but with different dimensions. From the side, the book may appear as a parallelogram. From far away, the book may appear small, and from up close, large. So, we can perceive a change in primary qualities without the object itself changing. Berkeley argues that the arguments that were meant to prove that secondary qualities exit only in the mind may with equal force prove that the same of primary qualities (PHK 15).

However, Berkeley’s line of argument here fails. There is a notable difference between the subjective judgment of primary qualities such as size or shape and subjective judgement of secondary qualities such as color. With respect to size, though my subjective judgement may vary, there is still an objective standard that can be appealed to. These standards do not depend on subjective interpretation to be utilized (Bakhurst 10). My subjective perception of color may have some sort of objective standard (e.g. a color wheel), but this is a standard that has been imposed by humans. In contrast, primary qualities operate on standards that would be agreed upon by any rational observer (Bakhurst