Overview

Berkeley’s Three Dialogues Between Hylas and Philonous in Opposition to Skeptics and Atheists is, as you probably guessed from the title, a dialogue. And with all dialogues in philosophy, the most important thing to know is which character is the smart one. That is, which one is speaking for the author and which one articulates the ideas that the author wishes to refute?

The smart one is Philonous, whose name means “lover of wisdom.” The one who is there to be refuted is Hylas, whose name is derived from the Greek word for matter.

In a nutshell, Berkeley tries to show that the idea of material substance is incoherent. The only kinds of things that can exist, he maintains, are ideas.

The dialogue is framed as a refutation of skepticism and atheism. The idea is that if there were such a thing as matter, we could not know what it is really like. The only things we can know are our own ideas. If matter exists outside our minds, then it could be very different from what we think it is. That possibility gives rise to skepticism about our knowledge: we might be wrong about external reality and cannot prove that we are right. There is an inevitable gap between what we think and what is real. By contrast, if ideas are all that exists, then there is no gap between what we think and what is real.

What about God? As we will learn in the second dialogue, most of the relevant idas are ideas in God’s mind. I do not want to give away the story, but God is going to be needed to explain why we have the ideas that we do. So atheism will be refuted as well.

Primary and Secondary Qualities

Berkeley’s general strategy in the first dialogue is to argue against the distinction between primary and secondary qualities.

The standard distinction between primary and secondary qualities, as found in, say, Galileo, Descartes, or Locke, holds that some qualities, like color, heat, and sound, are not qualities of objects themselves but rather due to the way we perceive them. These are the secondary qualities. The primary qualities are things like extension, shape, and number. These are real qualities of objects and do not depend on us.

One way of denying the distinction between primary and secondary qualities is to insist that the secondary qualities are just as real as the primary ones. Grass would be green even if were not here to see it.

Berkeley goes in the other direction. He accepts that secondary qualities are only found in our minds. But he denies the argument that primary qualities are different. Instead, he is going to argue that the arguments showing that secondary qualities are only found in our minds also apply to so-called primary qualities.