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Logical Fallacies

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Ms. Tees

on 19 February 2014

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Transcript of Logical Fallacies

Logical Fallacy
Fallacy = An argument that uses poor reasoning.

Logical Fallacy is, fundamentally, an error in logic - meaning the argument used does not hold up under logical scrutiny.
Argument from Ignorance:
Basing the truth of a premise only on whether it has been proven to satisfaction.
Argumentum ex culo
Various forms of making things up or lying.
Argumentum ad hominem
Attacking the opponent directly rather than addressing the opponent's idea.
Agumentum ad verecundiam
Begging the Question
Assuming the conclusion as part of the premise (similar to circular reasoning).
Negative Proof
Arguing that something must exist because there is no evidence it does not exist.
Argumentum ad Hitlerum
Saying something is bad because Hitler did it...
Logical Fallacies
Consider the following proposition:
1. Some men are doctors.
2. Some doctors are tall.
3. Therefore, some men are tall.

1. Some men are doctors.
2. Some doctors are women.
3. Therefore, some men are women.
One Single Proof
Dismissing all circumstantial evidence in favor of a single "smoking gun" that may not (and may not need to) exist
Ad hoc
Yanking shoddy explanations out of thin air / off the cuff - hastily constructed to support or explain a position or argument without underlying logic.

Make up excuses to dismiss contradictions - Homeopathic medicine
Moving the Goalposts
Changing evidential requirements in an argument once they have been met, "what I really meant was..."
False Analogy
Creating an analogy or metaphor (comparing objects or ideas with similar characteristics) to support an argument, but the conclusion made is not supported by the analogy due to the differences in the two.
Extending the analogy to prove one's point.
Red Herring
Bringing up a fact which is irrelevant to the issue, in an attempt to distract the opponent and/or audience.
Straw Man
Misrepresenting someone's argument to make it easier to attack by associating it to a more easily rejected position
False Fallacy Fallacy & The Fallacy Fallacy
False Fallacy Fallacy
Falsely claiming that a logically valid argument is fallacious.
The Fallacy Fallacy
Presuming that because the claim has been poorly argued, or that a fallacy has been made, that the claim is necessarily wrong.
Special Pleading
"Vegetarians want us to lice on leaves and grass!"

"Conserve Fuel? I don't have the time to go everywhere on foot or by bicycle!"
Poisoning the Well
Attempting to refute an argument based on the perceived veracity of the presenter.
Tu quoque
Where a criticism is falsely dismissed because its author is also guilty of the charge - To answer a criticism with a criticism.
Burden of Proof
Saying that the burden of proof lies NOT with the person making the claim, but with someone else to disprove.
Appeal to Authority
"ad populum"
Appeal to Ancient Wisdom
It's right because the Maya/Chinese/Hebrews said it thousands of years ago!
Appeal to Tradition
Just because it's always been that way doesn't mean it's the right way
Galileo Gambit
If someone is going against the tide of popular thinking, they must be right because the likes of Galileo were right, while in reality, Galileo was right because he had evidence.
because someone famous/powerful/respected believes it, it must be true
Circular Reasoning
The reasoner begins with what they are trying to end with - Circular reasoning works because circular reasoning works.
Sharp Shooter Fallacy
Ignoring the difference while focusing on the similarities, thus coming to an inaccurate conclusion - inserting meaning into randomness.

Cherry-picking data clusters to suit an argument, or finding a pattern to fit a presumption.
Slippery Slope
Asserting that if we allow A to happen, then Z will consequently happen too, therefore A should not happen.
Personal Incredulity
Saying that because one finds something difficult to understand that it's therefore not true.
False Cause
Presuming that a real, or perceived, relationship between things, means that one is the cause of the other.
No True Scotsman
Non sequitur
Arguably the most fundamental logical fallacy, this is claiming A implies B when it doesn't.
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