Does all knowledge come from experience ?
From the classical empiricist point of view, -traditionally associated with John Locke, and primarily his 'Essay Concerning Human Understanding'- almost certainly so. Locke's epistemological contention was that knowledge is derived from experiential concepts acquired in the form of sense-data. These sense-data were supposed, according to Locke, to be of primary and secondary qualities, which when combined with and abstracted from each other gave rise to tertiary qualities. Examples of primary qualities in an object would be the size and shape of, say; an apple. These qualities are independent of an observer and remain constant with or without our knowledge or appreciation of them. The red colour and fresh smell of the apple, would be examples of its secondary qualities; these qualities, Locke argued, are not intrinsic to the object in question, but rather are only manifest in the sensory perception of the observer.
The apple is red when we perceive it as such, however the degree of its redness is something that varies according to the individual, I might perceive it as a deep crimson, while another might think it as scarlet in hue. These secondary qualities of the apple, then, come into existence only upon receipt of the sense-data of which they are determined. Tertiary or complex concepts of objects are arrived at by the process of conjoinment, abstraction or combination of its primary and secondary qualities, to pursue the earlier example; one's concept of the apple's freshness, perhaps, would be determined by the combination of one's concepts of its shape, colour, smell, skin texture and taste.
Here the empiricist argument runs into the realm of inconsistency, especially in light of the attempt to extrapolate how these concepts come to be combined. The theory of direct combination suggests that simple concepts...