Unformatted text preview: has the following hypothetical
property: If all the premises are true, the
conclusion cannot be false.
That is, if you were to imagine that all the premises
were true, then it would be logically impossible for
the conclusion false at the same time
Logic guarantees of the truth of the conclusion, (now
provided that the premises are true) Valid Argument
Premise All actors are robots Premise Tom Cruise is an actor Conclusion Therefore, Tom Cruise is a robot Premise If Michigan scores the most points then they win the
game. Premise Michigan scored more points. Conclusion So, Michigan won the game Valid Argument
Premise Tom is happy only if the Tigers win, Premise the Tigers lost; Conclusion therefore, Tom is not happy.
The Argument Form is...
If A then B
A
Therefore, B When we say "If A then B" it means that, every time, if A is true or
false, then B is true or false also. Click to View the Linked YouTube Video Below Valid Argument Forms
i. If Joe makes this field goal, then Davison
wins
ii. Joe made the field goal .
iii. Therefore the Davison won. If P then Q i. If the patient has malaria, then a blood test
will indicate that his blood harbors the P.
vivax virus
ii. Blood test indicate that the patient’s blood
does not harbor the P. vivax virus.
iii. Therefore the patient does not have
malaria. If P then Q P
Therefore Q Not Q
Therefore
Not P Valid Argument Forms
i. Either the Detroit Tigers or the Giants will
win the World Series.
ii. The Tigers did not win the Word Series
iii. Therefore, the Giants won Either P or Q i. If John gets a raise, then he will buy a house.
ii. If John buys a house, he'll run for city
council.
iii. Therefore, if John gets a raise, he will run
for a position on the city council If P then Q Not P
Therefore Q If Q then R
Therefore ...
If P then R Valid Arguments
Premise If a plane is flying it is in the air. Premise Flight 999 is flying, Conclusion Therefore it is in the air. Premise If P then Q Premise P Conclusion Therefore, Q Valid Arguments
Premise If there are clouds in the sky, then rain is
possible. Premise No rain is possible. Conclusion Therefore, there are no clouds in the sky Premise If P then Q Premise Not Q Conclusion Therefore, Not P Valid Arguments
Premise Either Elizabeth owns a Honda or she
owns a Saturn. Premise Elizabeth does not own a Honda. Conclusion Therefore, Elizabeth owns a Saturn. Premise Either P or Q Premise Not P Conclusion Therefore, Q Valid Arguments
Premise All toasters are items made of gold. Premise All items made of gold are timetravel
devices. Conclusion Therefore, all toasters are timetravel
devices. Premise All P are Q Premise All Q are R Conclusion Therefore, All P are R Invalid Arguments
Invalid: An argument where the conclusion could be
false even if the premises are true
○ Premise: Steve owns a Lexus automobile.
○ Premise: Rich people own Lexus automobiles
○ Conclusion: Therefore, Steve must be rich
The Argument Form is...
● P is Q
● R is Q
● Therefore, P is R Invalid Argument Forms
i. Anyone who lives in th...
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This document was uploaded on 02/26/2014 for the course PHILOSOPHY 1101 at Douglas College.
 Winter '14

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