Philosophy of George Berkeley, 18th century thinker famous for “to be is to be perceived” and Principles of Human Knowledge, his greatest work.
Irish philosopher and Bishop of Cloyne, George Berkeley (March 12, 1685 – January 14, 1753) is renowned as the father of philosophical idealism, who showed that the materialism of John Locke and Isaac Newton was unsustainable. His most famous adage is “esse est percipi” (“to be is to be perceived”).
Causal Theory of Perception
Berkeley, like others, also noted that John Locke’s “causal theory of perception” implies a logical gap between the subject and reality. This gap is often called by philosophers as “the veil of perception.” The causal theory of perception holds that objects in the external world have a causal effect on the senses producing ideas in the mind of the observer.
For example, an ordinary glass seen by the eyes begins a chain of causal events first in the retina of the observer, followed by the neural pathway that leads the observer to see “a glass.”
Berkeley’s Idea versus Reality
Seeing the glass, however, is a construct inside one’s mind. As Berkeley claims, if the perception of the glass is a construct – or “idea” in the mind – then it follows that what is actually seen is not the real or actual glass, but only the idea itself.
Since all perceptions are generated inside the mind, there is no way of telling whether reality resembles a person’s ideas or not.
Berkeley’s Veil of Perception
Using a series of arguments through “veil of perception,” Berkeley concludes that since humankind never perceives anything called “matter” but only ideas, it is a weak conjecture to presume that there is a material substance lying behind and supporting perceptions.
Locke and Other Critics
Locke and others resisted Berkeley’s suggestion by making the distinction between primary qualities, such as solidity, figure and extension, and secondary qualities such as color, taste and smell, claiming that only secondary qualities are dependent on the mind.
Berkeley further claimed that perceptions are ideas produced by God who perceives everything at all times. Following his philosophy, a closed room still exists since ideas are perceived in the mind of God.
Berkeley’s Philosophical Works
A New Theory of Vision, 1709
Principles of Human Knowledge, 1710
Three Dialogues between Hylas and Philonous, 1713, Hylas personifies educated common sense and Philonous defends idealism, representing Locke and Berkeley himself.
De Motu or On Motion, 1729, he discusses Newtonian physics and rejects Isaac Newton’s views on space, motion and time.
The Analyst, 1734, a critique of the foundations of infinitesimal calculus, influential in the development of mathematics.