Gettier, "Is Justified True Belief Knowledge?"

What two points about "justification" does Gettier's argument rely on?

1) It is possible to be justified in believing something false 2) If P entails Q, and S seduces Q from P and accepts Q as a result of deduction, then S is justified in believing Q

In Gettier's two examples, what true propositions did Smith not know?

1st Case: Smith did not know that he also had ten coins in his pocket and it was unknown to him that he will get the job 2nd Case: Smith did not know that the place mentioned in proposition B (Barcelona) happens really to be the place where Brown is and that the Ford is a rental car

What is a necessary condition?

A condition (statement) Q is necessary for the truth of P iff whenever P is true, so too is Q

What is a necessary and sufficient condition?

A condition Q is necessary and sufficient for the truth of P iff P is true only if Q is true

What is a sufficient condition?

A condition Q is sufficient for truth of P iff whenever Q is true, so too is P

What is the JTB (Justified True Belief) account?

According to this traditional view, S knows that P iff: (i) P is true (ii) S believes that P (iii) S is justified in believing that P

In both cases, Smith deduces one proposition Q, that is justified and true, from another P. In each case, does Smith know P?

Although Smith has strong evidence to believe P, he does not know it in both cases

Edmund Gettier (1927-Present)

An American philosopher who became famous for what is now called the "Gettier Problem"

What is a deductive closure?

For any proposition P, if S is justified in believing P, and P entails Q, and S deduces Q from P and accepts Q as a result of this deduction, then S is justified in believing Q

According to Gettier, can one be justified in believing P and yet be wrong about the truth of P?

Yes, this can occur when a deductive closure is made

According to Gettier, is justified true belief knowledge?

Gettier shows, by means of two counterexamples, that there are cases where individuals had justified the true belief of a claim but still failed to know it; thus, he claimed to have shown that the JTB account is inadequate and can not account for all of the knowledge

What does Gettier assert about the JTB account?

He claims that the three conditions do not constitute a SUFFICIENT condition for the truth of the proposition that S knows that P

In both cases, Smith deduces a justified true proposition from a FALSE one. Does this suggest a further condition we could add to the JTB account to patch the hole (i.e. provide necessary and SUFFICIENT conditions for knowledge)?

In order for a deduced proposition to be a JTB and knowledge, it must originate from a justified true proposition

Explain Gettier's second case: The Ford

Smith has strong evidence for: (f) Jones owns a Ford, because at all times in the past within Smith's memory, Jones always owner a Ford, and Jones just offered Smith a ride in a Ford. Smith believes on the basis of randomly inferring from (f) that: (g) Either Jones owns a Ford, or Brown is in Boston (h) Either Jones owns a Ford, or Brown is in Barcelona (i) Either Jones owns a Ford, or Brown is in Brest-Litovsk. It turns out that Jones doesn't own a Ford (he just rented one), and Smith has no idea where Brown is, who coincidentally is in Barcelona. → Smith holds a justified true belief in (h) because his deductive reasoning was accurate and he had strong evidence to base this premise on. → However, Smith does not know (e).

Explain Gettier's first case: The Job.

Suppose that Smith and Jones have applied for a certain job. And suppose that smith has strong evidence for: (d) Jones is the man who will get the job, and Jones has ten coins in his pocket, because the president of the company assured Smith that Jones would be selected and because Smith counted the coins in Jone's pocket 10 minutes ago. He believes on the basis of inference from (d) that: (e) The man who will get the job has ten coins in his pocket. Unknown to Smith, he himself will get the job, and unknown to hum, he has ten coins in his pocket. → Smith holds a justified true belief in (e) because his deductive reasoning was accurate and he had strong evidence to base this premise on. → However, Smith does not know (e).