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Entries Tagged as 'Fallacy Friday'

Friday Fallacy: Affirming the Consequent

May 13th, 2011 1 Comment

In my last Friday Fallacy post, I looked at the fallacy of  denying the antecedent. There I discussed conditional statements, statements of the form “if P then Q”. Examples would be statements such as “if it is raining then the grass will be wet” or “if the US had not shot Bin Laden then he would still […]

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Fallacy Friday: Denying the Antecedent

April 30th, 2011 31 Comments

This week I will look at the fallacy of denying the antecedent. Before I can elaborate exactly what is involved in this fallacy, it is important to introduce and analyse some valid arguments that are superficially similar. Modus Ponens One of the very first valid inferences one learns in logic is modus ponens. To use […]

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Friday Fallacy: Equivocation

April 16th, 2011 14 Comments

In my post on Assessing Arguments I noted that a valid argument is one where it is impossible for the premises to be true and the conclusion false. I gave the following example: Premise: All men are under 10 feet tall; Premise: John is a man; Conclusion: John is under 10 feet tall. This argument […]

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Fallacy Friday: Ad Ignorantiam (Arguments from Ignorance)

April 8th, 2011 4 Comments

In the discussion following last week’s Fallacy Friday topic, Ad Populum, LJ asked about the ad ignorantiam fallacy. In particular she wanted to know about its relationship to creationism. I suspect LJ was being sarcastic but despite this it is worth exploring this issue a bit. First, we should recall that a fallacy is not simply […]

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Fallacy Friday: Ad Populum (Appeals to Popularity)

April 2nd, 2011 16 Comments

This week I am going to look at the ad populum fallacy. Ad populum is Latin for “appeal to the people”. This fallacy occurs when a person argues that a particular claim is true because a large number of people accept it. Put crudely it contends that a position is true because it is popular – […]

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Fallacy Friday: Ad Misericordiam (Appeal to Pity)

March 25th, 2011 13 Comments

This week I will look at the ad misericordiam fallacy, the fallacy of appealing to pity. Perhaps the best example I have come across is one used by my friend Francis Beckwith; In his book Politically Correct Death: Answering Arguments for Abortion Rights, Beckwith cites the following letter to the editor: The fallacy in this […]

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Fallacy Friday: Petitio Principii (Begging the Question)

March 19th, 2011 7 Comments

For the last few Fridays I have been publishing a blog series on logical fallacies. This begs the question, what fallacy will I discuss today? The above sentence illustrates how the  phrase “begs the question” is commonly misused. To test how pervasive this misuse is I typed “this begs the question” into Google and limited it […]

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