George Berkeley's Epistemology

I'm taking a "Classics of American Thought" class. So far we've read John Winthrop on why economic and social inequality is actually pleasing to God, and John Locke on the basis for property rights and his epistemology, particularly the difference between primary (shape, size, solidity, number, and motion) and secondary (color, taste, smell, sound, and texture) qualities of objects.

This week is George Berkeley who sets out, in "Three Dialogues between Hylas and Philonous," (1713) to oppose Sceptics and Athiests by, in the first dialogue, adopting the Sceptics' point of view, namely that it is impossible to definitively prove the existence of objects. It's impossible because, as I understand it, we are slaves to our perceptions and to our experiences, so that everything we think we perceive is actually the production, in our mind's eye, of an archetype. For example, our eyes perceive a round, red, shiny thing with a little brown protruberance at the top. The particular combination of these shapes and colors is compared with a set of archetypes stored in our memory, resulting in the idea of an "apple" to form in our minds. We then proceed as if the apple exists.

Basically, as he presents the Sceptical point of view, Berkeley is saying that it's impossible to escape from our perceptions. We can't be certain that our perceptions are real -- after all, we perceive things in dreams but that doesn't make them real -- so we are left with doubt as to the nature of reality.

I follow the scepticism argument with respect to the sensory perceptions like color and sound, but things like shape, size, and motion are a bit more difficult for me. Can't we use a yardstick to measure the size of something? Or a yardstick and a stopwatch to measure its speed? I guess Berkeley is saying that we have to perceive in order to make those measurements, so we're back where we started.

What about pure intellectual ideas, like that of a circle? According to Berkeley's treatment of Scepticism, one cannot conceive of a circle without giving it some secondary qualities, such as, "Is it filled in or an outline?" If filled in, what color is it? If an outline, how thick is the line? Etc.

But what if I conceive of a circle as the set of points in a plane a units from a specified center point? I suppose Berkeley would say that I'm simply using other archetypes and symbols.

Where all this is going remains to be seen. Now I'll read an exchange of letters between Berkeley and Samuel Johnson.