Argument TacticsArgument TacticsCorrectly and incorrectly appliedCorrectly and incorrectly applied
About Logical ArgumentsAbout Logical Arguments
Arguments are made up of premises and conclusions.
Premise: If A is true, then B is true.
Premise: A is true.Conclusion: Therefore, B is true.
About Logical ArgumentsAbout Logical Arguments
An argument can be valid, but not sound.
Valid: If boa constrictors bite their prey, it dies.A boa constrictor bit my dog; therefore, my dog is dead.
Sound: If boa constrictors get ahold of their prey, they squeeze it to death.A boa constrictor got ahold of my dog; therefore, my dog is dead.
A Few Types of Arguments
A Few Types of Arguments
Ad Absurdum
“Some argue that marijuana is a gateway drug to heroin and cocaine. Will popping Reeses Pieces lead to popping ecstasy?”
-Caitlin Niman
A Few Types of Arguments
A Few Types of Arguments
Modus Ponens
If A is true, then B is true.A is true; therefore, B is true.
“If the dam broke, the valley would flood. The dam broke; therefore, the valley flooded.”
A Few Types of Arguments
A Few Types of Arguments
Obviously, this can be switched around and elaborated.
If and only if A is true, then B is true.B is true; therefore, A is true.
“If and only if the dam broke, the valley would flood.
The valley has flooded; therefore, the dam broke.”
A Few Types of Arguments
A Few Types of Arguments
Argument by Analogy
“Parents look out for their children;so, teachers should look out for their
students.”
“An argument, just like a house, needs a solid structure.”
A Few Types of Arguments
A Few Types of Arguments
Mentioning things by not mentioning them
“I won’t even mention her clothes.”
“There’s no need to recount the Senator’s past indiscretions.”
(This isn’t so much an argument as a tactic.)
Some Logical FallaciesSome Logical FallaciesPost hoc ergo propter hoc: “After it, therefore because of it.
“I only caught a cold after I shook hands with you.”
“Kennedy was assassinated because the CIA failed to kill Castro.”
Some Logical FallaciesSome Logical Fallacies
Ad hominem: “At the person”
“I don’t think Sarah Palin’s qualified to be president.”
“That’s because you’re sexist.”
“It was just one dance!”“Only a man would say that.”
Some Logical FallaciesSome Logical Fallacies
Begging the question
Misused: “This new evidence begs the question of whether he can be trusted.”
It actually looks like this: “O.J. Simpson did not kill his wife, because he is a world-
class football player, not a murderer.”
Some Logical FallaciesSome Logical Fallacies
The slippery slope
“If we legalize gay marriage, the institution of marriage is going to deteriorate
everywhere.”
“If I let you do that, I have to let everyone do it.”
But, don’t be fooled: “fallacies” aren’t always fallacious.
Non-Fallacious UsesNon-Fallacious UsesPost hoc ergo propter hoc: “After it, therefore because of it”
“I only caught a cold after I shook hands with you.”
“He only stole my bike after I broke his Xbox.”
“My computer only crashed after I dropped it.”
Non-Fallacious UsesNon-Fallacious Uses
Ad hominem: “At the person”
“I don’t think Sarah Palin’s qualified to be president.”
“That’s because you’re sexist.”
“The senator broke all of his campaign promises.”“Politicians always lie during campaigns.”
Non-Fallacious UsesNon-Fallacious Uses
The slippery slope
“If we legalize gay marriage, the institution of marriage is going to deteriorate everywhere.”
“If we set a precedent with this case, more extreme rulings will follow.”