Professor Rappaport
What is philosophy?
Philosophia - "love of wisdom"
PREMISES
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V
CONCLUSIONS
EXAMPLE
(Premise 1) Jane is taller than Bob.
(Premise 2) Bob is taller than Dave.
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V
(Conclusion) Jane is taller than Dave.
We say that the premises imply or entail the conclusion.
Or, the conclusion is a consequence of the premises.
Validity - An argument is valid just in case the premises really imply the conclusion.
I.e., if the premises are true, then the conclusion must be true.
Validity does not require that the premises or the conclusion be true.
Soundness - An argument is sound just in case it is valid and the premises are true.
Example of a valid argument
(P1) Snow is blue.
(P2) The ocean is blue.
(C) Therefore, snow is the same color as the ocean.
Example of a valid argument
(P1) Either today is Saturday or 2+2=5.
(P2) Today is not Saturday.
(C) Therefore, 2+2=5.
Example of an invalid argument
(P1) If it's raining today, then I should bring an umbrella.
(P2) It is raining today.
(C) Therefore, cows drink milk.
There are two ways to challenge an argument
VALID or INVALID?
(P1) If John walks to work, he will be late.
(P2) John does not walk to work.
(C) Therefore, John will not be late.
VALID or INVALID?
(P1) Most basketball players are tall.
(P2) LeBron James is a basketball player.
(C) Therefore, LeBron James is tall.
A paradox is an argument that appears convincing, but the conclusion is absurd.
The Paradox of the Heap
WTF, mate?!
The Paradox of the Heap
The Paradox of the Heap
The Paradox of the Heap