October 19, 2007
1)
JTB Analysis
a.
The JTB analysis of knowledge has the logical form of a biconditional (ie: any
statement of the form P if and only if Q)
i.
The only way for a conditional to be false is if the antecedent is true but
the consequent is false
ii.
Why? Because every conditional just “says” that its antecedent is
sufficient for its consequent and that its consequent is necessary for its
antecedent.
iii.
So a counterexample to a conditional statement (if P, then Q) will be of
the form P but Not Q.
iv.
A biconditional is two conjoined conditionals; such that, for any statement
of the form P if and only if Q to be true, it must be true that both
conditionals i and ii are true:
1.
i. If P, then Q
2.
ii: if Q, then P
v.
So, a counterexample to any biconditional statement (P iff Q) will be of
either these two forms
1.
i. P but Not Q or
2.
ii. Q but Not P
2)
A closer look at the JTB analysis
a.
Since the JTB analysis is a biconditional, for it to be true both of its two
conditionals, i and ii, must be true
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 Fall '08
 LEWIS
 Logic, Justified true belief

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