Class 3 - Theaetetus's First Definition

Notes from Class 3

Welcome back! We’re now going to tackle Theaetetus’s first argument, where he says that knowledge is perception. But before we do this, we’ll check in, as usual.

Breakout groups to check in

We’ll start as usual with some breakout groups, just to check in.

Introduction

The idea that knowledge is perception makes some kind of intuitive sense: we perceive a cat, for example, and on this basis, we know that there is a cat.

More than this, if we had no perceptions at all, what knowledge could we have? Surely our knowledge would be massively depleted. Would we know anything at all?

Questions

To get us started, I want you to take two minutes to think of one thing that you find puzzling about the text, or one question you have. We’ll put these on the shared document. Then we’ll talk through them.

The Floating Person

Here, there’s an interesting thought experiment from the Islamic philosopher Ibn Sina, called the “Floating Person” argument.This doesn’t derive directly from Plato’s thinking, but it is relevant to the topic we are exploring. The thought experiment goes like this.

Imagine somebody is floating in empty space, unable to touch anything or to perceive anything. They are in total sensory deprivation. What can they know? You can find out more by listening to this posting on Philosophy Bites.

The Floating Person - a writing exercise

Writing task

Avicenna describes the floating person as follows:

He will not doubt his affirming his self existing, but with this he will not affirm any limb from among his organs, no internal organ, whether heart or brain, and no external thing. Rather, he would be affirming his self without affirming for it length, breadth and depth. And if in this state he were able to imagine a hand or some other organ, he would not imagine it as part of his self or a condition for its existence.

You know that what is affirmed is other than what is not affirmed and what is acknowledged is other than what is not acknowledged. Hence the self whose existence he has affirmed has a special characteristic of its being his very self, other than his body and organs that have not been affirmed.

Hence the one who affirms has a means to be alerted to the existence of the soul as something other than the body—indeed, other than body—and to his being directly acquainted with this existence and aware of it. If he is oblivious to this, he would require educative prodding.

This translation is from Michael Marmura, “Avicenna’s ‘Flying Man’ in Context,” The Monist 69 (1986), p. 387.

Imagine you are the floating person. What do you experience? Remember that you have no sense input at all! You don’t even have a sense of your own body. What is this knowledge? What is it like to be the flying person? Write for seven minutes.

We’ll share these in the group.

What is the relationship between knowledge and perception

So we might be sceptical about whether knowledge and perception are the same. Nevertheless, it is clear that knowledge is somehow tied up with perception.

In the following two sessions, we are going to explore the initial claim that knowledge is perception (today), and Socrates’s counter-argument (in the next session).

A Note on Knowledge and Perception

Of course, this example — although it raises question of sense perception and knowledge — is not necessarily a refutation of Theaetetus’s view. So the floating person arguably has a perception of their own soul, and this may amount to knowlege. So we still potentially have a connection between knowledge and perception, even if this isn’t sense perception.

Can we know something independent of perception? It’s an interesting question. Incidentally, Ibn Sina doesn’t talk about perception of the self, but instead of affirming. It is not entirely clear that this is the same thing (in fact, it probably isn’t!), although it’s also not clear if affirming can be independent of perception. :)

Questions on Theaetetus’s argument

Now, let’s look in more depth at Theaetetus’s argument. Here are some questions to discuss in breakout groups.

1. What do you think Theaetetus means when he says that knowledge is perception?
2. What do you think Protagoras means when he says that the human being “is the measure of all things”?
3. What is the significance of the argument about the wind — being both cold and hot, depending on the observer? What are the implications of this for our theories of knowledge?
4. In the modern world, Protagoras’s view is sometimes referred to as “relativism”. This is the idea that truth is relative to the perceiver. Can you think of any examples of this view?
5. What are the arguments in favour of relativism? What are the arguments against it?

We’ll discuss these ideas in the main group to finish the session.

Homework

Your homework is to re-read READING 2, focussing on Socrates’s counter-argument 184b4-186e10. Think about the following questions:

1. How does Socrates argue against Theaetetus’s view?
2. How convincing are Socrates’s counter-arguments?
3. Can you find any other, better counter-arguments?

Next Session

During the next session, I’ll not be here, as I have a hospital appointment that I unfortunately can’t reschedule. So I’m going to set the following work:

i) Some further reading ii) Something to watch (a short video) iii) A written task to be completed in class time.