George Berkeley (1685-1753)

1. Locke’s empiricism:

“There is nothing in the mind that was not first in the sense”

Locke's Epistemology

1. All knowledge is grounded in sense experience (perception)

2. Sense experience gives rise to ideas

3. We only have immediate access to our ideas

Locke’s Metaphysical Claim:

• External, material objects exist

• External objects are the cause of our ideas

So, Locke’s picture admits the reality of

1. Matter

2. Mind/Ideas

It is a form of dualism

What do we know about external objects?

Qualities: The properties of external objects

Primary qualities: extension, solidity, shape, mobility, and number

– For the object to be experienced at all, it must take up space and therefore must have a shape, volume, motion, etc

– Primary qualities can be thought of as how an object is characterized mathematically/physically

Secondary qualities: colour, taste, smell, sound, texture

– Sense dependent

– Known through our 5 (6,7,8,…) senses

Common view:

Primary qualities are in our ideas and also in the external object

• Because they give the physical characterization of the object

Secondary qualities are only in our ideas

• They are sense-dependent so they necessarily result from how our senses work

• So they need us to exist

Examples:

Taste: the sweetness of an apple is not in the apple

Taste is dependent on the organization of the sugars in the object interacting with how our taste sensation works

Heat: results from the motion of particles (primary qualities)

Our senses translate this undetectable motion into the sensation of heat

But it is the motion, not the heat, that is in the object

Colour: result of certain surface reflectance properties (primary qualities) interacting with our sense of sight

Light bounces off the object which we sense with our eyes

What light bounces off depends on the surface properties of the object and the colour we see depends on our eyes

For a dog, the colour would be different

So…

Primary qualities we perceive are also actually in the external object—in this sense, they ground the reality of external objects

Secondary qualities are only in our ideas

2. Berkeley

His empiricist epistemology is the same as Locke:

Epistemology

1. All knowledge is grounded in sense experience (perception)

2. Sense experience gives rise to ideas

3. We only have immediate access to our ideas

Berkeley is concerned with the metaphysical status of external, material objects

Question: Can we prove that external objects exist?

In other words: Do external objects have any real (primary) qualities?

The dialogue between Berkeley and Locke goes something like this:

Hey, Locke, I agree with you about all knowledge being a result of experience and that we access that knowledge through ideas,

But…

If you follow your own argument through to its ultimate conclusion, there is no basis for believing that primary qualities exist in external objects.

So, there is no basis for believing in the existence of external objects

There is no matter, there are only ideas

Berkeley is pushing a philosophical point against Locke. It is that Locke can’t consistently hold that material objects exist while holding the brand of empiricism he does

3. Berkeley’s approach

We’ve already seen why secondary qualities are considered to only be in our ideas: they result from the way our senses work—they are sense-dependent. Berkeley offers a number of his own arguments supporting this claim. We’re going to focus on a specific one:

Perceptual Relativity

Here’s what Berkeley is going to do:

1. Give us a perceptual relativity argument for why secondary qualities exist only in the mind (taken from Locke himself)

2. Then show us why, by parity of reasoning, primary qualities also exist only in the mind

The Argument: Perceptual relativity

Experiment:

1. Put one of your hands in cold water

2. Put the other in hot water

3. Put them both in room temperature water

Result: You feel the room temperature water to be BOTH hot and cold

But no one object could be both hot and cold

That’s absurd!

Conclusion:

Hotness and coldness cannot be in the external object

Instead, such a quality is sense-dependent and only in our ideas

And, indeed, we can run this argument for all other secondary qualities

Objection: Might one of them just be false?

Berkeley: Which one? What criteria, other than a similar experience, could decide which one is false?

You would simply be comparing another idea, subject to the same perceptual relativism

So, Berkeley has shown that our secondary qualities are mind-dependent

What about the primary qualities?

Example 1: a pen

To you it is a fairly small object

It fits in your hand

You can break it if you really wanted to

Now, imagine the size of a pen as perceived by an ant

It is huge!

So the extension of the pen seems to vary relative to the perceiver

Example 2: penny

If you hold up a penny directly at eye level it appears circular

If you put it on the table and look at it, it appears oval or elliptical

So, the shape of the penny seems to vary relative to the perceiver

In both cases, if extension (pen example) and shape (penny example) were really in the objects, then we would have to conclude that the very same thing had two different extensions or shapes

But that is absurd!

Conclusion

Therefore, by parity or reasoning, we must conclude that primary qualities are also not in the external object, but rather only in our idea of that object. Locke’s metaphysical claim that external objects exist cannot be sustained since none of its qualities exist in an external object. Since both primary and secondary qualities only exist in our ideas, the objects themselves only exist in our ideas. Or, more properly, they are our ideas.

So…

These “external objects” are only in our ideas! All that is left in the world -- since there are no objects external to my mind -- are ideas. And since ideas depend on perception:

esse is percipi (to be is to be perceived)

“When we do our utmost to conceive the existence of external bodies we are all the while only contemplating our own ideas.”

~Berkeley

Reading for next Tuesday:

335-344