The essence of the philosophical debate, therefore, centered on Berkeley’s refusal to believe that reality consisted of abstractions that could be separated from a material object. In order to explore this debate in more depth, this essay will examine Berkeley’s critique of Locke regarding the viability of primary and secondary qualities. As a preliminary matter, for Berkeley, the proffered distinction between primary and secondary qualities, an integral theoretical concept underpinning John Locke’s notion of Abstract Ideas, was an issue of fundamental importance. Our knowledge of the world around us, in Berkeley’s view, was dependent on the viability of this distinction. Berkeley’s ultimate rejection of this distinction, and the theory of Abstract Ideas was bold; Locke, after all, was not the first philosopher to believe in the validity of the distinction. Indeed, Berkeley challenged some of the greatest thinkers as the distinction had also been embraced by such luminaries as Descartes, Newton, and Galileo. A brief presentation of Locke’s approach to primary and secondary qualities is necessary because it highlights the bases of Berkeley’s attacks and because Locke’s work served as the authoritative statement of the viability of the distinction between primary and secondary qualities....
He also pointed out the epistemological problems which, he asserted, rendered Locke's distinction nothing more than speculation. Locke, in Berkeley's view, was hardly an empiricist.
Berkeley could simply not accept Locke's assertion that an underlying quality could be separated from the mind. Locke stated, by contrast, that a quality was a power that was capable of producing an idea in our mind. This definition was significant because it separated the quality from our mind; more particularly, Locke established a causal relationship in which a quality inherent in an object caused us to have an idea about that object. Berkeley, because he rejected the separation, also rejected the notion of causation. Berkeley's strongest criticisms, however, derived from Locke's attempt to divide a quality into two specific types. This criticism dealt with Locke's attempts to draw a distinction between what he termed primary qualities and secondary qualities. Locke characterised primary qualities as being inseparable from the object being observed. Everything had fundamental properties. These fundamental properties were constant.
Locke viewed solids, extensions, figures, motion or rest, and number as primary qualities; Berkeley, for the reasons mentioned below, argued and demonstrated that these primary qualities did not exist. The denial of these primary qualities served as the basis for his rejection of the notion of abstraction of ideas. Berkeley stated that these qualities were illusory and therefore could not produce in us ideas about the object being observed. Ideas were ideas and nothing more. Nor did Berkeley accept the premise that a