Section 7.3 What Do You Know? Knowing What Knowledge Is McGraw-Hill © 2013 McGraw-Hill Companies. All Rights Reserved.

7.3-2 Traditional Analysis of Knowledge  Knowledge is justified true belief.  S knows a proposition P if and only if: P is true, S believes that P is true, and S is justified in believing that P is true.

7.3-3 Gettier’s Guy in Barcelona  Suppose Smith has strong evidence for the claim that Jones owns a Ford but doesn’t know where his friend Brown is.  So he concludes that (h) Either Jones owns a Ford or Brown is in Barcelona.  It turns out that Jones does not own a Ford, but Brown is in Barcelona.  Even though Smith is justified in believing (h), he doesn’t know (h).

7.3-4 The Defeasibility Theory  Knowledge is undefeated justified true belief.  Diagnosis of the Gettier problem: there is additional evidence which, if known, would defeat the knowledge claim.

7.3-5 Thought Experiment: Lehrer and Paxson’s Demented Mrs. Grabit  Suppose Lehrer sees someone who looks like Tom Grabit steal a book from the library.  Mrs. Grabit, however, testifies that it was his twin brother John who stole the book.  This piece of evidence defeats your claim (d) that Tom stole the book.  But unbeknownst to you, Mrs. Grabit is a compulsive liar. So you do know (d) despite the defeaters.

7.3-6 The Causal Theory  Knowledge is suitably caused true belief.  Diagnosis of the Gettier problem: what makes the claim true is not what caused the person to believe it.

7.3-7 Thought Experiment: Goldman’s Fake Barns  Suppose that Henry is driving through the countryside and points out to his son “That’s a barn.”  Suppose it is a barn, but suppose further that there are a number of fake barns in the area.  Even though the son’s belief that the object is a barn is caused by a real barn, he doesn’t know that it is.

7.3-8 The Reliability Theory  Knowledge is reliably produced true belief.  Diagnosis of the Gettier problem: the beliefs were not produced by reliable means.

7.3-9 Thought Experiment: Lehrer’s Human Thermometer  Suppose Mr. Truetemp has a thermometer implanted in his skull that causes him to have reliable beliefs about the temperature.  Suppose further that Mr. Truetemp never checks his temperature beliefs.  Even though his beliefs are reliably produced, they don’t constitute knowledge.

Virtue Perspectivism  An intellectual virtue is a skill or ability that reliably produces true beliefs, like perception, memory, and reason.  Virtue perspectivism claims that knowledge is apt belief—belief that is taken to be true because of one’s intellectual virtue.

Evaluating Performances  A performance is accurate if it achieves its goal.  A performance is adroit if it manifests the skill of the performer.  A performance is apt if it’s accurate because it’s adroit.

Knowledge as a Performance  The goal of knowledge is true belief. So: A belief is accurate if it’s true. A belief is adroit if it manifests the intellectual virtue of the believer. A belief is apt if it’s believed to be true because of that virtue.  Only apt belief is worthy of being considered knowledge.

Animal Knowledge vs. Reflective Knowledge  Animal knowledge is apt belief.  Reflective knowledge is belief that we know to be apt.

Virtue Perspectivism Solutions to Gettier-type Problems  Gettier’s Guy in Barcelona has neither animal nor reflective knowledge because his belief is not apt.  The subjects in Goldman’s fake barns and Lehrer’s Human Thermometer have animal knowledge but not reflective knowledge.  The subject in the Demented Mrs. Grabit may have both animal and reflective knowledge.