1. Recap So Far: Direct Realism
What can you remember?
Problem
Response
Illusion PV
Hallucination
Time-Lag

2. Problems with IDR
Before the holidays we discussed two problems with the indirect realist view.
If we can’t perceive the external world directly (because our perceptions are mediated by sense data) then this can lead to:
Scepticism about the nature of the external world.
Scepticism about the existence of the external world.

3. Responses – What can you remember?
What can we know about the nature of the external world?
How can we know the external world exists?

4. Do they defeat IDR?
Whilst the problem of scepticism is a big issue for IDR it does not disprove the theory entirely.
We COULD still be perceiving sense data produced by physical objects in the external world, but if the sceptic is correct there is NO WAY of knowing FOR SURE what that external world is like or WHETHER IT EXISTS.

5. Enter Berkeley
One philosopher who believed he could show some issues with IDR that would truly undermine the theory was George Berkeley ( ), it’s his theory of idealism we’ll be focusing on next.
But first, why does Berkeley have a problem with Indirect Realism?

6. Lesson Objective
To outline the attack Berkeley makes on the primary / secondary quality distinction and consider whether he is successful.

7. Primary and Secondary Qualities – What can you remember?
Primary Qualities
Secondary Qualities

8. Berkeley’s Attack on the P+S Quality Distinction…
Berkeley took issue with the distinction Locke outlined between primary and secondary qualities. He thought:
Primary qualities and secondary qualities are actually inseparable. You can’t have one and not the other.
Primary qualities are just as mind-dependent as secondary qualities.

9. Berkeley’s Attack on the P+S Quality Distinction…
Read through the information on page 81+82:
Why does Berkeley think that primary qualities and secondary qualities are inseparable?
Why does he think that Primary Qualities are also mind-dependent?

10. Berkeley’s Attack on the P+S Quality Distinction…
Berkeley outlines these two arguments in a series of dialogues between two characters - Hylas and Philonous, with Hylas taking the place of the Indirect Realist (or at the very least someone who agrees with the primary / secondary quality distinction) and Philonous criticising this view.

11. Berkeley’s Attack on the P+S Quality Distinction 1…
Philonius starts by outlining why he thinks the primary qualities each have mind-dependent aspects, he gives a number of examples to illustrate this: Size – Large and Small Motion – Fast and Slow Shape – Round and Square

12. Berkeley’s Attack on the P+S Quality Distinction 1…
He then questions whether Hylas could even imagine the primary qualities without these mind-dependent aspects: Can we imagine size without it being relative to our perception? Motion without it being relative to our perception? Shape without it being relative to our perception?

13. Berkeley’s Attack on the P+S Quality Distinction 1…
Hylas (rightly) can’t, so Philonius ultimately concludes that primary qualities are just as mind-dependent as secondary qualities, as we can’t imagine them without these mind-dependent parts. Essentially even when it comes to Primary Qualities our perspective plays a part in how they are perceived. This means, argues Philonius, like secondary qualities (i.e. colour) we cannot say objects have one real shape, size or motion that is independent of how they are perceived.

14. Berkeley’s Attack on the P+S Quality Distinction 1…
If you can form in your thoughts a distinct abstract idea of motion or extendedness, having none of those sensible qualities—swift and slow, large and small, round and square, and the like—which we agree exist only in the mind, then I’ll capitulate. But if you can’t, it will be unreasonable for you to insist any longer on something of which you have no notion.

15. Berkeley’s Attack on the P+S Quality Distinction 1…
Consequently the very same arguments that you agreed to be decisive against the secondary qualities need no extra help to count just as strongly against the primary qualities also. Besides, if you trust your senses don’t they convince you that all sensible qualities co-exist, that is, that they all appear to the senses as being in the same place? Do your senses ever represent a motion or shape as being divested of all other visible and tangible qualities?

16. Berkeley’s Attack on the P+S Quality Distinction 1…
P1: Size, shape and motion are as subject to the variability of perception as colour, smell or sound. P2: In the case of these ‘secondary’ qualities we can’t say the object has one ‘real colour’ that is independent of how we perceive it. P3: Therefore we cannot say that an object has one real shape or size or motion, independent of how it is perceived. C: Therefore, the primary qualities of objects are just as mind-dependent as secondary qualities.

17. Berkeley’s Attack on the P+S Quality Distinction 2…
Previously when discussing Primary and Secondary qualities we stated that secondary qualities are not essential to an object, they can be removed and the object will remain. Primary qualities on the other hand, are essential. To demonstrate this we gave the example of an apple and suggested it could be imagined without any colour, smell, taste, sound and so on (i.e. secondary qualities), but not without it’s shape, size, position or motion.

18. Berkeley’s Attack on the P+S Quality Distinction 2…
Like some of you, Berkeley does not find this argument convincing. He thinks that an object that could not be perceived by any secondary qualities would not be perceived at all. I can only have an idea of an object via it’s SENSIBLE qualities (the qualities I learn about through my senses), and if we take those away, nothing remains of it. Berkeley believes that we cannot truly conceive of an object that has only primary qualities. Try again, can you really imagine an apple made up of only primary qualities? Can you imagine anything that is only made up of primary qualities?

19. Even Locke thought he had a point…
Locke also admitted (although not in response to Berkeley who lived later) that he had some difficulty with the idea of matter stripped of it’s secondary qualities, he also thought it was hard to imagine. He called it ‘something’, but admitted ‘I know not what’.

20. Berkeley’s Attack on the P+S Quality Distinction…
Size, shape and motion are as subject to the variability of perception as colour, smell or sound.
In the case of these ‘secondary’ qualities we can’t say the object has one real colour that is independent of how we perceive it.
Therefore we cannot say that an object has one real shape or size or motion, independent of how it is perceived.
C: Therefore, the primary qualities of objects are just as mind-dependent as secondary qualities.
In addition, it is wrong to think that we can imagine an object (e.g. an apple) having only primary qualities and being devoid of its sensory qualities (e.g. colour).
C: So our idea of secondary qualities are actually inseparable from our ideas of primary ones.

21. Consequences?
Since primary and secondary qualities are actually inseperable, and both are mind-dependent, Locke seems to be wholly mistaken with his attempt to distinguish between the two. In fact, this undermines Indirect Realism as a whole, since, if Berkeley is correct we don’t ever perceive anything that is mind-independent. Why bother assuming there is something there at all? This ultimately leads to Berkeley’s idealism – the belief that all that exists are minds and their ideas - that we’ll be covering the next few lessons.

22. Interesting Side Note:
This criticism only works against primary and secondary qualities and thus indirect realism. If we take a direct realist approach (or a philosophical direct realist approach) and assume that we perceive the external world directly, Berkeley’s criticism does not apply. All qualities are part and parcel of the objects in question. There is nothing mind-dependent.

23. Response:
One response to Berkeley is to deny that he has proven everything is mind-dependent. We can accept that secondary properties may appear to change due to our perception and the condition of our sensory organs, but still believe that they are caused by very real qualities of the object in question. Similarly we can accept that primary properties may appear to change as we change our perception but still think they are caused by very real objects in the external world. All Berkeley has done (if he has done that) is show that primary qualities can also vary according to perception, he has not proven that both primary and secondary qualities are entirely mind- dependent.

24. Summary – Without Notes!
Can you summarise the two main reasons Berkeley has an issue with the Primary / Secondary quality distinction on your whiteboards?

25. Homework - Research
What is the ‘likeness principle’ according to Berkeley?
Why is this a problem for indirect realism?
Due: Next Monday

26. Summary
To outline the attack Berkeley makes on the primary / secondary quality distinction and consider whether he is successful.