George Berkeley

A Treatise Concerning the Principles of Human Knowledge

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A Treatise Concerning the Principles of Human Knowledge Summary

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George Berkeley’s philosophical work, A Treatise Concerning the Principles of Human Knowledge (1710), also known as the Treatise, explores the nature of human perception. Refuting arguments made by his contemporaries, the work prompted further intellectual discourse upon its publication, which was Berkeley’s intention. An Irish bishop, philosopher, and empiricist, Berkeley is known as a leading philosopher of the eighteenth century. He spent many years traveling around Europe, mingling with leading scholars across the continent, until he settled into a professorship at Trinity College, Dublin.

In the Treatise, Berkeley aims to explore why something exists, how we know it exists, and the very nature of existence. As an empiricist, Berkeley believed that all knowledge comes from sensory experience and reflection. For example, most of us know what an apple is. We know an apple is an apple because of its physical structure. An apple can be green, red, small, large, etc., but it is still an apple. However, if we have never seen or heard of an apple before, we do not recognize it. We cannot name it, and we cannot classify it. Our brain doesn’t understand an apple is an apple, because it has never experienced an apple before. Like his fellow empiricists, Berkeley believed that all knowledge comes from experience. We cannot know anything without experiencing it first.

In the Treatise, Berkeley takes this concept even further. He primarily tackles the arguments made by John Locke, his leading contemporary. Locke believed that everything around us exists in a vacuum. It exists separately from us. Calling this substance “matter,” we shape it according to our perception. For example, the apple exists whether we can identify it or name it. It has a shape, mass, and density, and it takes up space in the world around us. It must, then, exist whether we perceive it or not.

Berkeley disagrees with Locke on this point, believing, for example, that the concepts of shape, mass, and density are manmade concepts. They exist because someone perceived them and named them—a shape is a shape because it possesses the hallmarks of a shape. If the original perceiver had looked at these concepts completely differently, we would see them differently, too.

Berkeley sets out the argument that nothing material exists; there is no such thing as a material substance. Everything we see is simply an idea that we have engaged with and perceived in a certain way. We know a familiar object like a chair when we experience it, but the chair does not exist in the material world. In short, the chair exists because someone perceives it through his or her senses. It does not exist in a reality separate from us—there is no such thing as “matter.”

To make this easier to understand, a straightforward example would be how someone born blind cannot perceive color, such as red or blue. He does not know what it looks like, has never experienced it, and so, cannot name it. The same can be said for someone born deaf; she cannot perceive, make sense of, or experience a piece of music, and so she does not know what “music” is.

Berkeley contends that ideas are clear even if language is not. This is where semantics is an issue, and where we have trouble translating one language to another. Though we know what a chair is, we might have different ways of describing it. While the language is not clear, the idea of the chair is clear. We are all describing the same thing.

Berkeley describes how we perceive things and form detailed ideas. He asserts that first, we sense something. We use our senses to engage with it—for example, we smell it, feel whether it is soft or prickly, and perceive its size and shape. Our mind organizes these ideas in a familiar way, and so we perceive something as a chair or an apple. Since these ideas only exist when they are perceived, if we did not exist to perceive them, they would not exist, either.

In the Treatise, Berkeley takes this concept further again. He separates ideas into two categories—strong and faint ideas. Strong ideas depend on our senses. They are distinct and they make sense because our minds organize them properly. Faint ideas are less reliable. Faint ideas are the images, sounds, and experiences we imagine when we are daydreaming or thinking. We have created these ideas ourselves.

The most important point regarding ideas is that they only ever exist in one person’s mind. It does not matter whether they are strong or faint ideas—we will never think precisely the same way as another person. This is inevitable and, as Berkeley suggests, it is proof that nothing exists outside of perception. If it did, we would all interpret it the exact same way.

Although Berkeley suggests nothing is real, he does believe there is order in the universe. He believes a creator, whether it is God or another entity, is responsible for our world and our ability to perceive things. Whoever—or whatever—created the concept of existence, nothing exists without a perceiver. Everything is an idea, and nothing is tangibly real.