Knowledge and Perception in Plato

(Originally written July 9, 2006 in Book 4)

The History of Western Philosophy
Bertrand Russell

Chapter 18 - Knowledge and Perception in Plato

Modern men take for granted the empirical knowledge comes from perception. Plato believed knowledge could not be derived from the senses (thus not from perception).

Plato believed '2+2=4' is genuine knowledge but statements like 'snow is white' is too ambiguous to be considered truth.

Plato was plagued by the idea of a relational proposition (as were most philosophers up to and including Hegel).

Plato argues against Protagoras' doctrine of man is the measure of all things. This is a precursor to arguing against knowledge as perception.

He argues from Heraclitus' point of view that because everything is changing to state knowledge is perception is the same as stating knowledge is not perception.

He argues that we perceive through eyes and ears, not with them. Then finds that some knowledge is had without any sense organ. Since knowledge can be obtained without the aid of sense organs (like the eyes and ears) perception can have nothing to do with knowledge.

Knowledge, not coming from perception via the senses, cannot come from the impressions they give. Thus the mind must recall the impression to find knowledge. Reminiscence is knowledge.

Linehan - If knowledge cannot be obtained from impressions, which are obtained by perception through the senses, then how can reminiscence which conjures up impressions be knowledge? If knowledge is not had in the foundation of reminiscence it cannot have it anywhere.

Perception cannot grasp existence; without existence there is no truth.

Linehan - I don't understand most of this chapter. The bracket on page 153 marks the beginning of where I became confused. The bracket on page 159 (the end of the chapter) marks the end or beginning of my confusion. It is ceaseless it seems in this chapter or at least Russell's argument against Plato's.