Dr Tom Kerns
North Seattle Community College



Bishop George Berkeley

(1685-1753, age 68)

(This lecture is a longish one; you may want to print it out for reading)

By his early 20s young George Berkeley had read Locke's Essay Concerning Human Understanding and had found it to be eminently sensible and persuasive. As regards those last two questions that Locke had posed, however, Berkeley was unconvinced that Locke's answers had been adequately thought out.

Locke's two questions (and his answers) had been:

  1. Can we know that objects continue to exist even when they are not being perceived by anyone? Locke's answer: Well, perhaps we cannot be absolutely certain of their continued existence during the times when they are not being perceived, but common sense tells us that in all probability they do continue to exist even when they are not being perceived.

  2. And can we know that objects exist even when they are being perceived? Locke's answer: Surely no one would be so skeptical as to hold that we cannot know objects exist when they are being directly perceived. Common sense tells us that of course we can know that objects exist during the intervals that we are directly perceiving them.

Berkeley was not convinced that Locke's answers to these two questions were precisely accurate. Berkeley proposed to think through these two questions as clearly as he possibly could, following all the principles of good common sense and relying only on what our actual experience clearly teaches us.

The two books in which he articulates his examination of these questions are The Principles of Human Knowledge, written in 1710 when Berkeley was 25 years old; and Three Dialogues Between Hylas and Philonous, written three years later when he was 28. The Three Dialogues is a shorter work and many people (though not all) find the argument as expressed in The Dialogues to be simpler and easier to follow.

(In his later years, Berkeley actually came from Ireland to the British colonies (now the US) and spent three years in Rhode Island hoping to establish a college in the new world. The University of California campus at Berkeley, as well as the town of Berkeley, is actually named for him. (Americans, however, pronounce the name differently than do those in the British Isles; Americans call that town "BURK-lee," whereas the proper British pronunciation of the good Bishop's name is "BARK-lee.")

For Berkeley the question came down to what we mean when we say that something "exists." He analyzes this question from several different angles and concludes that all we can possibly mean when we say that a thing exists is that the thing is being perceived. To exist, and to be perceived, for Berkeley come down to the same thing. To be means to be perceived, or esse est percipi, is Berkeley's famous principle.

If this is what we mean by "to be," then clearly things exist only when they are being perceived. (If this is true, then it would seem to raise some difficulties; but Berkeley will have an answer for these obvioius difficulties.)

Then Berkeley asks whether "physical matter" exists. His answer will clearly be that it can be said to exist if we can perceive it, but that it cannot be said to exist if we cannot perceive it. So the question comes down to whether we can perceive physical matter or not.

Now the answer to this question might seem pretty obvious to most of us, but Berkeley asks us to look at the question more closely. When we say that we perceive physical matter, what exactly is it that we claim to be perceiving? I see this beautiful little red agate that I found on the beach yesterday, for example, but what exactly am I sensing? I am actually having a complex sense perception that includes the sensations of hard, reddish, a certain shape and size, a certain smoothness, etc. Thus, what I am actually perceiving are sensations (which Locke, but not Berkeley, thought were caused by qualities), but not physical matter as such.

So, according to Berkeley, all those qualities I am perceiving - the sensations of redness, hardness, shape, etc. - all actually exist only in my mind, not out in a some hypothesized "external world."

So if we perceive only sensations and do not ever actually perceive physical matter, then according to Berkeley we cannot claim to experience physical matter, and thus have no basis for believing that physical matter exists.

That, in a much-abbreviated nutshell, is Berkeley's analysis of the question of whether physical matter exists or not. He says we have absolutely no empirical evidence that matter does exist since we never experience it directly (or even indirectly).

So what sort of existents are there in the world, according to Berkeley? You'll recall that Locke believed that there are four kinds of existents: material things, perceptions, minds, and God. Bishop George Berkeley believes the only kinds of existents are perceptions and minds. He believes in God, of course (he is an Anglican bishop, after all), but sees God as Infinite Mind. Thus, the list of existents for Berkeley would look like this:

  1. Minds

    • finite human minds
    • God's infinite mindPerceptions that exist in those minds

  2. Thus, for Berkeley no physical objects or physical matter exist at all.

What we consider to be things do continue to exist (though they are not made of physical matter) even when no humans are directly perceiving them, according to Berkeley. And the reason for their continued existence is that God's infinite mind continues to perceive these "things," i.e., continues to generate these perceptions, even when we do not perceive them.

An old scholastic limerick says it like this:

There was a young man who said "God
Must think it exceedingly odd,
If He finds that the tree,
Continues to be
When there's no one about in the quad."

"Dear Sir, your astonishment's odd;
I'm always about in the quad.
And that's why the tree
Continues to be,
Since observed by yours faithfully,
- God."

George Berkeley is therefore not considered a "realist" (since he does not hold that there is a real physical world existing out there), but is instead said to be an "idealist," i.e., one who believes that everything that exists is ideas and perceptions (and minds).

You will recall that we saw earlier in the quarter that Berkeley's position, while it clearly seems odd to many people, is not entirely without precedent. We saw that similar conclusions are held by others (cf. quantum physics, tulpas, and the "My Dream" story). Berkeley, however, comes to this conclusion not by any esoteric path or religious tradition or scientific method, but simply by carefully following out what common sense and experience teach us if we listen to them closely and examine them carefully.

His writings really are quite simple and not at all difficult to follow. You may wish at some point to look at either his Principles or his Three Dialogues.


When young David Hume read John Locke, and later read George Berkeley he found their arguments highly sensible and utterly convincing. He agreed that Berkeley had carried Locke's arguments to their next proper level, but he wondered if Berkeley too had not let some of his own unexamined assumptions creep into his philosophy as well.

David Hume was convinced that we do, of course, experience sensations and perceptions, but he believed that both Locke and Berkeley left two major concepts entirely unexamined. These two concepts, both of them absolutely fundamental to the way we think about things, and both of them almost entirely unquestioned by any philosophers (at least in the West) up until Hume's time, are two of the most fundamental assumptions in human thought.

These two fundamental concepts are

    1. cause and effect, and
    2. the notion of self, identity, or mind.

Hume will examine these two concepts with a highly sharp-witted and analytically critical vengeance.