6.3 Abstraction and Idealism

What this lecture covers

Continuing the attack on the resemblance thesis, this lecture explains why Berkeley denies that we can even form the idea of a primary quality, like shape, in abstraction from a secondary quality like color. That denial rests on Berkeley's rejection of Locke's doctrine of abstraction, and it is the route by which Berkeley arrives at his famous idealism: the claim that mind-independent bodies are literally inconceivable.

You'll come away able to state Locke's doctrine of abstraction, explain Berkeley's objection to it using the triangle example, and see how the lecture connects the failure of abstraction to the emergence of unintelligible 'something I know not what' properties in modern physics.

Key ideas

• Empiricism's pressure on primary qualities: since Locke holds all ideas derive from experience, and we only ever experience shapes as colored, it is natural to ask whether our idea of shape is inseparably bound up with color.
• Locke's doctrine of abstraction: general ideas, like the idea of 'man', are formed by noticing similarities among particular cases and stripping away distinguishing details.
• Berkeley's attack on abstraction: you cannot form the idea of a triangle that is neither equilateral, isosceles nor scalene, because no such triangle could exist; abstraction of this kind is impossible.
• From abstraction to idealism: if you cannot conceive a shape without color, and secondary qualities like color cannot exist outside a mind, then you cannot conceive of a primary quality existing independently of a mind either.
• Berkeley's idealism: mind-independent bodies are inconceivable, so reality ultimately consists only of minds (spirits) and their ideas.
• Samuel Johnson's stone-kicking reply: a famous, if philosophically weak, common-sense objection to Berkeley's idealism.
• 'Something I know not what': rather than accept idealism, one option is to admit that body has properties, like solidity, that we can only grasp indirectly through their effects, a move that modern physics later normalizes with properties like charge and spin.

Walkthrough

From resemblance to abstraction (0:12)

The lecture explains why an empiricist who thinks all ideas come from experience faces pressure to say our idea of shape is contaminated by the color through which we always perceive it, unless we can abstract a pure idea of shape.

Locke's doctrine of abstraction (1:14)

Using the example of a child forming the general idea of 'man' from encounters with particular men, the lecture sets out Locke's account of how general ideas are built by leaving out distinguishing detail.

Berkeley's objection (2:16)

Berkeley argues abstraction of this kind is impossible, since you cannot form an idea of a man who is neither tall nor short, nor a triangle that is neither equilateral, isosceles nor scalene, because nothing answering to such an idea could exist.

From abstraction to idealism (3:17)

Because he denies abstraction, Berkeley concludes we cannot conceive of a primary quality apart from the secondary qualities bound up with it, and since secondary qualities are inherently mental, mind-independent bodies turn out to be inconceivable, yielding Berkeley's idealism.

Living with 'something I know not what' (5:18)

Rather than accept idealism, the lecture considers conceding that properties like solidity can only be grasped indirectly, through their effects, and connects this to how modern physics treats properties such as mass, charge and spin as things we can only describe through equations, not intuitively understand.

Before you watch

• Watch "6.2 Problems with Resemblance" first, since this lecture continues directly from Berkeley's attack on resemblance.
• Recall Locke's account of general ideas and abstraction from earlier in the course.

Check your understanding

1. How does Locke's doctrine of abstraction explain the formation of a general idea like 'man'?
2. Why does Berkeley think you cannot form the abstract idea of a triangle that is neither equilateral, isosceles nor scalene?
3. Explain the chain of reasoning that takes Berkeley from rejecting abstraction to idealism.
4. Why does the lecture compare 'something I know not what' properties to concepts like charge and spin in modern physics?