1. 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 it’s difficult to see what we can know for sure about the external world itself.
Scepticism about the nature of the external world.
Scepticism about the existence of the external world.

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

3. Enter Berkeley
We said last lesson that due to the fact he believed that both primary and secondary qualities were inseparable from objects, and both were mind-dependent, Berkeley argued indirect realism was false. Instead he supported a position known as idealism. Whiteboards: Basic definition of idealism.

4. Idealism
The immediate objects of perception are mind- dependent objects. These objects don’t represent reality, they are reality. There are no mind- independent objects.

5. Lesson Objective
To explain the likeness principle and the issue it causes for indirect realism.
To explain Berkeley’s master argument for idealism.

6. Homework - Research
What is the ‘likeness principle’ according to Berkeley?
Why is this a problem for indirect realism?

7. Homework - Research
What is the ‘likeness principle’ according to Berkeley?
Why is this a problem for indirect realism?
Only ideas can be ‘like’ other ideas.
This means the indirect realist cannot claim that their ideas can be ‘like’ or ‘represent’ the external world.

8. The Likeness Principle – Breaking it Down…
To truly make sense of what Berkeley is saying with his ‘likeness principle’ we need to return to our definition of indirect realism:
“The immediate objects of perception are mind- dependent objects that are caused by and represent mind-independent objects.”
For Berkeley represent essentially means the same thing as resemble. His belief is that the indirect realists are arguing that their perception / sense data generally resembles the external mind-independent objects.

9. Dialogues…
Philonous: “The indirect realist may claim that our ideas do not exist without the mind; but […] they are copies, images or representations of certain originals that do.” It’s not hard to see why Berkeley thinks this, indirect realists definitely seem to have suggested as much, even if they’ve not said it outright.

10. The Problem…
Philonous: ‘How can that which is sensible be like that which is insensible?”

11. How might we usually check whether two things resemble each other?
The Problem…
How might we usually check whether two things resemble each other?
A dress your friend is wearing and a dress in the shop.
A meal on a menu and the one the waiter brings you.
A person on tinder and the person you’ve just met.
The idea I have in my mind of a dog and the dog in front of you.

12. Breaking it down further…
How might we usually check whether two things resemble each other?
The issue that Berkeley has is that, as an empiricist (someone who thinks we can gain knowledge from our senses / by testing things), he believes that we can only be sure two things resemble one another if they can be compared.
Couple this with the fact that, if Berkeley is right, we only perceive ideas, and you are left with the view that only ideas can resemble other ideas – as we have nothing mind-independent to compare them to.

13. The Likeness Principle – Breaking it Down…
So to return again to the Indirect Realist definition:
The immediate objects of perception are mind- dependent objects that are caused by and represent mind-independent objects.
For Berkeley the IDR is wrong to say that his ideas can resemble something mind-independent, he has no way of comparing his ideas with anything mind-independent and thus cannot go as far as making this claim. At best we can only claim that ‘ideas can only be like / resemble other ideas’.

14. Dialogues…
In defense of this view Philonous asks: “Can a real thing in itself invisible, be like a colour; or a real thing which is not audible be like a sound? In a word can anything be like a sensation or an idea that is not another sensation or idea?”

15. Task:
Use page 83 of the textbook to help you answer the following questions:
What is the likeness principle?
What is Berkeley’s reasoning for supporting the likeness principle?
What examples does he give in his dialogues to support this view?
Extension: Do you think he has a point? How strong is his argument? Why?

16. Critique:
Let’s return to our dog example for the moment: The idea I have in my mind of a dog and the dog in front of you. Is it possible that my idea of a dog resembles the dog in front of you even if you cannot compare the two?

17. Critique:
Just because we cannot identify the resemblance between two objects does not mean they definitely do not resemble one another:
It’s entirely possible that all our ideas could resemble the external world, even if we can never truly compare them to check.
More specifically an Indirect Realist may argue that there are certain qualities (primary) that absolutely do resemble external objects, even if we can never prove this resemblance beyond a shadow of a doubt.

18. Is this a strong response?
Critique:
Just because we cannot identify the resemblance between two objects does not mean they definitely do not resemble one another:
It’s entirely possible that all our ideas could resemble the external world, even if we can never truly compare them to check.
More specifically an Indirect Realist may argue that there are certain qualities (primary) that absolutely do resemble external objects, even if we can never prove this resemblance beyond a shadow of a doubt.
Is this a strong response?

19. Berkeley’s Third Argument:
Even if his likeness principle fails, and the attack on the primary secondary quality distinction is not convincing, Berkeley thinks he has one final argument that will defeat other views of perception for good. He believes this argument to be so strong he has no need for any other. In fact, he has so much faith in this argument he names it: The Master Argument <Dramatic Music>

20. Read through the outline given by Philonous and Hylas on page 444:
Whiteboards!
Read through the outline given by Philonous and Hylas on page 444:
What do you think the master argument is stating?
What example does Philonous give to illustrate it?

21. The Master Argument
Philonous asks if Hylas can conceive of any collection of properties or qualities to exist outside of the mind. Hylas replies that he is thinking of a tree that is currently unperceived by anyone. What fatal mistake does Berkeley think Hylas has made here?

22. The Master Argument
Philonous objects that what Hylas is currently thinking of depends on his mind. He isn’t actually thinking of a tree that exists independently of any mind; he is imagining a tree standing ‘in some solitary place’ where no one perceives it. But all the time, he is thinking of such a tree. We cannot think of a tree that is neither perceived nor conceived of, because in doing so we are conceiving of it.

23. The Master Argument There are no mind-independent objects.
If you suggest the existence of a mind-independent object (e.g. an unperceived tree), then you are thinking of it, so it is mind dependent.
Therefore there are no mind- independent objects.
Is Berkeley correct? How strong is this argument?

24. Criticism
If Berkeley is correct with his view of idealism, then no objects exist outside of our perceptions of them. But this seems to misunderstand the position of direct realists and indirect realists – both might accept that the idea of the tree exists only in our minds, but this is not to say that the tree itself is therefore mind-dependent. So when I imagine a tree standing unobserved in a distant forest, it is quite possible for me to be thinking of an object which exists outside of any mind, even though I am using my mind to represent this thought.

25. Is this a strong response?
Criticism
If Berkeley is correct with his view of idealism, then no objects exist outside of our perceptions of them. But this seems to misunderstand the position of direct realists and indirect realists – both might accept that the idea of the tree exists only in our minds, but this is not to say that the tree itself is therefore mind-dependent. So when I imagine a tree standing unobserved in a distant forest, it is quite possible for me to be thinking of an object which exists outside of any mind, even though I am using my mind to represent this thought.
Is this a strong response?

26. Outline the master argument as given by Berkeley.
Task
Outline the master argument as given by Berkeley.
Identify one criticism of the argument and clearly explain why it is a criticism.

27. Lesson Objective / Summary
To explain the likeness principle and the issue it causes for indirect realism.
To explain Berkeley’s master argument for idealism.

28. Homework
Research, identify and write down 3 criticisms of Berkeley’s / philosophical idealism.
Bring them with you next lesson and be prepared to share them with the class.
Due next lesson.