John Locke is a prominent figure in the history of Western philosophy. His ideas on epistemology, or the study of knowledge, have had a significant impact on modern philosophical thought.

However, Locke’s views have not gone unchallenged. One of his most notable critics is George Berkeley, an Irish philosopher who lived in the 18th century.

Berkeley was highly critical of Locke’s epistemology, particularly his theory of perception and ideas. According to Berkeley, Locke’s theory failed to provide a satisfactory account of the nature of reality and knowledge. In this article, we will explore Berkeley’s criticisms of Locke’s epistemology in detail.

Locke’s Theory of Perception

Locke believed that all knowledge comes from experience. He argued that our minds are initially blank slates at birth and that all our ideas come from sensory experiences. According to Locke, our senses give us direct access to the external world, and our minds simply receive and process the information provided by our senses.

However, Berkeley challenged this view by arguing that there is no such thing as sense data independent of perception. He believed that we only perceive ideas or mental representations of objects rather than objects themselves. For Berkeley, there is no external world that exists independently of perception.

Idealism vs Materialism

Berkeley was an idealist who believed that everything exists in the mind or consciousness. He claimed that material objects do not exist independently but only as perceptions in the mind. According to him, objects are just collections of ideas and do not exist outside our minds.

Locke, on the other hand, was a materialist who believed that there is a physical world outside our minds that exists independently. He argued that we can know about this external world through our senses.

Berkeley criticized Locke’s materialism by arguing that it leads to skepticism since we cannot know anything about an external world that is beyond our perception. He believed that the only way we can know anything is through our own perceptions.

Primary and Secondary Qualities

Locke distinguished between primary and secondary qualities of objects. Primary qualities, such as size, shape, and motion, are objective properties of objects that exist independently of perception. Secondary qualities, such as color and taste, are subjective properties that depend on the perceiver.

Berkeley rejected this distinction by arguing that all qualities are subjective. He claimed that primary qualities are no more objective than secondary qualities since they too depend on perception. According to Berkeley, all properties of objects are mental constructs rather than objective features of the external world.


In conclusion, Berkeley’s criticisms of Locke’s epistemology were wide-ranging and fundamental. He challenged Locke’s assumptions about the nature of perception, the existence of an external world, and the distinction between primary and secondary qualities. Berkeley’s idealism remains a significant challenge to materialist views of reality today.

In light of these criticisms, it is clear that Locke’s theory has limitations in explaining how we know things about the world around us. However, his ideas have still had a significant impact on modern philosophy and continue to be studied and debated today.