Solution #5: Reliabilism

JTB Definition of Knowledge

x knows that p if and only if

1. x believes that p
2. p is true
3. x is justified in believing that p

Is this definition right?  Would a different definition help us overcome our evil deceiver worries?
Edmund Gettier--definition is not right because the three conditions are not jointly sufficient

Before looking at counterexamples--

1. Forget about the evil deceiver, make common sense judgments.
2. Justification is one thing, truth is another.
3. Justification spreads through logical reasoning.  If you're justified in believing that p, and you know that p logically entails q, then you're justified in believing that q.

Gettier Case I, in cartoon form:

Credit: this is a modified version of an SMBC cartoon by Jack Weinersmith.
 http://www.smbc-comics.com/index.php?db=comics&id=2458

Credit: this is a modified version of an SMBC cartoon by Jack Weinersmith.
http://www.smbc-comics.com/index.php?db=comics&id=2458

Henry and the Barns

1. Henry believes he's looking at a barn
2. He is in fact looking at a barn.
3. He's justified in believing he's looking at a barn.

But because of all the fake barns in the area, Henry doesn't know he's looking at a barn! So the JTB definition is not right!

Broken Clock Counterexample (more realistic!)

The clocks in Hyer Hall were broken all last year.  Imagine Sally doesn't know this. She comes into Hyer Hall, looks at the clock, and sees it says 12:00.  She thus believes that it's 12:00.  But note: she would have believed the same thing had it actually been 11:00 or 1:00.

1. Sally believes it's 12:00
2. It is in fact 12:00
3. Sally is justified in believing it's 12:00

Sally meets all three conditions but she doesn't know it's 12:00!  So the JTB definition is not right!

New "reliabilist" definition of knowledge:

x believes that p if and only if

1. x believes that p
2. p is true
3. under the relevant circumstances x is reliably correct on the topic of p

Being reliably correct in the relevant circumstances vs. having justification

• Having justification is having reasons, evidence, being able to explain why you believe that p
• Being reliably correct is just getting it right, under the circumstances

On this definition, why doesn't Smith know? Why doesn't Henry know? Why doesn't Sally know?

How is this going to help us with the evil deceiver?  Stay tuned!

• Monday we'll talk about this
• We will also talk about how Descartes thought he'd solved the evil deceiver problem