Select Works of George Berkeley (2 vols.)

In A Treatise concerning the Principles of Human Knowledge, Berkeley repudiates Locke’s theory of human perception. Where Locke argued that ideas come from one’s experience of an external, material world, Berkeley argued that the world itself is composed only of ideas. Berkeley held that ideas can only resemble other ideas: an idea in the human mind can only resemble an idea in the external world, not a material object. Consequently, Berkeley argued, being necessitates perception by a perceiver.

Going further, Berkeley argued that it is impossible to prove the existence of material objects external to the self, since all knowledge comes through one’s senses and therefore gives only knowledge of those senses. He argued that Locke’s assertion that primary qualities exist in abstraction, and are therefore knowable only through secondary qualities, was mistaken. It is only possible to know the qualities that are immediately perceptible to the human mind. If they are not directly perceptible (as Locke’s primary qualities were), then there is no way to know them and, therefore, we cannot say that they exist.

In Three Dialogues between Hylas and Philonous, Berkeley sets up a Socratic dialogue between his own idealist views, in the person of Philonous (“lover of mind”), and the more Lockean views of Hylas (“matter”). Philonous argues that, while it is common sense to assume that the objects you perceive are real, it is against common sense to assume that those objects exist independent of perception. Through Philonous, Berkeley puts forward his “master argument.” The argument is essentially that it is impossible truly to conceive of an object outside of the mind because in the very act of trying to conceive of that object it is in the mind.

Berkeley also puts forward his theory that God is the perceptive mind that is always present and, therefore, is the mind that gives sensible qualities to objects. God groups various perceptions together. For example, humans experience the perception “touching water” and “feeling wet” at the same time. These patterns of perception are the subject of scientific study and described as laws of nature. However, they are not qualities which are inherent to an abstract material object. They are only assigned to objects by the mind of God.