(1685-1753)

George Berkeley was born March 12, 1685 at Dysert Castle in Ireland. He went to Trinity College in Dublin, where, among other things, he studied John Locke.

In 1709, he wrote An Essay Towards a New Theory of Vision. He asked, if a man, born blind, recovered his sight, what would he see? Berkeley reasoned he would see a meaningless array of qualities, which he would interpret as in his mind, and certainly not extended further than his eyes. Only repeated connection between the sights he sees and those same objects touched would lead him to learn shapes, distances, and so on. Later operations actually restoring people’s sight supported his theory.

Space (extension), therefore, is a mental construct, a matter of coordinating the relationships between what we see and what we experience through touch. We will see this idea of space as a mental thing again in Kant’s theory.

In 1710, he wrote The Principles of Human Knowledge. If, as Locke said, all knowledge comes through the senses, then we can know nothing that does not come through the senses. Extension in space, the shapes of things, their resistance to touch, their colors, tastes, smells,... all these do in fact come through the senses. But when does matter come through the senses? When do you see matter, or feel it, or taste it? All you ever experience through the senses are qualities, never a substance!

Matter is therefore a theory without evidence. Since the atheism of Berkeley’s day relied a great deal on materialism, he felt he had laid a knock-out punch!

Of course, it’s not just atheists who believe in matter -- nearly everyone does. It’s “common sense.” Dr. Johnson thought he gave the perfect rebuttal to Berkeley’s idea when he kicked a rock as hard as he could: The pain that rock caused him could hardly be denied! But Berkeley would (and did) note that all anyone could know about the rock was its shape, location, color, i.e. information of the senses, including the sense of pain if you are stupid enough to kick it.

Esse est percipi, Berkeley said: To be is to be perceived.

So what happens to things when we are not looking at them, touching them, or kicking them? Do they vanish every time we turn around? Berkeley said of course not! Things -- as collections of qualities -- always remain, but in God’s mind, which encompasses everything.

When a tree falls in the forest, and there’s no one to hear it, does it make a sound? Berkeley would say it does, because God hears it. This is perhaps the purest, and most eloquent, version of idealism ever. Only the Mahayana (northern) Buddhists have a similar idea in their “mind-only” philosophy. In their case, they refer not to God but to Buddha-mind.

Berkeley went on to spend some time in Rhode Island, waiting for a grant to start up a college in Bermuda, which never arrived. Berkeley in California was named for him. He became (Anglican) Bishop of Cloyne in 1734, and died at Oxford in 1753 at the age of 68.