What Is the Difference Btw Impressions & Ideas?

Impressions exist as an experience, that fact cannot be denied. Empiricism is the philosophy that knowledge must come from impressions, or direct experience. Using our senses, we induct reasoning through the mind from our immediate environment. However, impressions differ from our various viewpoints. Bertrand Russell's example of the table, which has no definitely agreeable properties, shows how our varied perceptions do not give us a notion of substance (what underlies the properties). Bishop Berkeley took John Locke's "commonsense" empirical foundation, and was unable to induct the existence of any thing beyond minds, and ideas in minds. He argues that we have no idea whatsoever what substance may be, and there is no justification for its existence.

An idea is qualitatively very similar to an impression; it only differs in force and vivacity. This was stated by David Hume in his Treatise of Human Nature. By this he means that ideas are simply recollections of impressions. A pure "truth of reason", an idea that can be known to be true by reasons alone, does not exist by this philosophy. In Theatetus' discussion with Socrates was the foundation for modern rationalist thought. A rationalist is one who believes (like Socrates) that the nonperceptual source of knowledge is Ð''reason'. Without the existence of reason isolated from perceptual experience, rationalism cannot be true.

Descartes built a foundation of knowledge upon his doubts about the validity of his own perceptions. He relied on the fact of his own existence and deductive reasoning to create a reasonable belief system. This rational theory is countered by Hume, the empiricist who classified ideas as simple or complex arrangements and associations of simple impressions. He called ideas Ð''faint images of impressions in thinking and reason.