Brandeis University, Philosophy Department
Fall 2003
Brandeis University Web Stite

Knowledge
as JTB

Professor Andreas Teuber
Prof. Teuber


I. Knowledge as Justified True Belief (JTB):

(1) You must believe p.

(2) Your belief that p must be true.

(3) Your belief that p must justified.


II. The Theory of JTB: For any individual S and any proposition p, S knows that p if and only if

(1) S believes that p.

(2) p is true.

(3) S is justified in believing that p.


III. Modified JTB:

(3)' A belief is justified to the extent required for knowledge if and only if it is caused by the facts (grounds, evidence and/or reasons) that make it true. .


IV. Further modification of JTB:

(3)' 'A belief is justified if and only if it is inferred from other beliefs that are themselves known to be true. .


V. An Argument for Skepticism:

(1) If S knows that p, then it isn't possible that S is mistaken in believing that p.

(2) It is possible that S is mistaken in believing that p.

(3) S doesn't know that p.


VI. Descartes' Foundationalism:

(1) I now believe I am standing in the Phil S-7 class.

(2) My present belief is clear and distinct.

(3) Clear and distinct ideas are true.

(4) I know that I am now standing in the Phil S-7 class. .


VII. Bringing God back In /Descartes' defense of the clear and distinct ideas assumption:

(1) My idea of God is an idea of a perfect being.

(2) There must be at least as much perfection in the cause of something than there is in the effect.

(3) The cause of my idea is a perfect being, i.e., God himself.

(4) God exists.

(5) God is no deceiver.

(6) My mind is not infallible, but God would not have furnished me with a mind that leads me to false beliefs on each and every occasion, no matter how carefully I reason and no matter how much evidence I consult.

(7) If God had done this, he would be a deceiver.

(8) God is no deceiver.

(9) If I reason carefully and make sure that my ideas are clear and distinct, I can be certain they are true.

(10) Clear and distinct ideas are true.

 

 


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