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Knowledge

Glenn Mason-Riseborough (11/9/2000)

Counterexamples to Justified True Belief (JTB) Theory

In Is Justified True Belief Knowledge? Edmund Gettier purports to give two counterexamples to the JTB theory of knowledge. What are these, and in what way are they intended to be counterexamples? Do you think that they are a knockdown to the JTB theory? Why or why not?

Reliability Theory of Knowledge (RTK)

Suppose that Fred is a disembodied brain in a vat, but he thinks that he has a body and a perfectly normal life. A conscientious scientist and a powerful computer ensure that the illusion is complete: when he decides to get up and walk out of a room, it seems to him that he actually does so, even though in fact he has no body and is always in precisely the same place. Fred’s experiences are indistinguishable from the experiences of someone who is actually doing these things.

Suppose that Fred believes (because the scientist has stimulated a certain set of neurones) that the sun is shining. Do you think that Fred knows the sun is shining? What would the reliability theorist say?

For all you know, you could be a brain in a vat. Given this possibility, would the reliability theorist say that you know the sun is shining? Why, or why not? Do you agree with this theorist?

The KK-Principle

The RTK rejects the KK-Principle. What is this principle? Do you think that the rejection of the KK-Principle is a problem for the RTK?

Kongzi, The Analects, 2:17:

The Master said, ‘Yu, shall I tell you what it is to know. To say you know when you know, and to say you do not when you do not, that is knowledge.’

Zhuangzi, Chapter 2:

Gaptooth asked Royal Relativity, ‘do you know what all things agree upon as right?’

Royal Relativity said, ‘how could I know that?’

‘Do you know that you don’t know it?’

‘How could I know that?’

‘Doesn’t anyone know anything?!’

‘How could I know that? But even so, suppose I tried saying something. How could I possibly know that when I say I know something, I don’t not know it? How could I possibly know that when I say I don’t know something, I don’t know it? …’