informal fallacies 2

21
Fallacies of Presumption When an argument takes for granted a belief that is in fact debatable.

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Page 1: Informal fallacies 2

Fallacies of PresumptionWhen an argument takes for granted a belief that is in fact debatable.

Page 2: Informal fallacies 2

Begging the QuestionAn argument begs the question if and only if one or more of its premises can be accepted only if the conclusion has already been accepted. Since in any such argument, at least one premise assumes the conclusion, that premise cannot be a reason for accepting that conclusion.

The argument is said to “beg,” rather than to support, its “question” or conclusion.

Page 3: Informal fallacies 2

The treatment of the animals in our zoo is humane,

given that animals are not treated inhumanely in this

zoo.

The premise here (that animals are treated humanely) relies on the conclusion being true (that the animals are not treated inhumanely), so it begs the question.

Page 4: Informal fallacies 2

1. Homer wrote the Odyssey.

2. Homer existed.

Once again, the premise requires that the conclusion is true.

Page 5: Informal fallacies 2

Free trade will be good for this country. The reason is patently clear. Isn't it obvious that unrestricted commercial relations will bestow on all sections of this nation the benefits which result when there is an unimpeded flow of goods between countries?

Page 6: Informal fallacies 2

Begging the question against

When an argument begs the question, at least one premise assumes the conclusion being argued for.

When an argument begs the question against, at least one premise assumes something is in need of support.

Page 7: Informal fallacies 2

1. Whoever is less productive should have lower

wages.

2. Women are less productive than men.

3. Hence, women should have lower wages.

The premise that women are less productive is, besides being outrageously offensive, in serious need of evidential support. Thus it begs the question against.

Page 8: Informal fallacies 2

1. No person should be denied freedom

2. Bruno is a person

3. It follows that Bruno is entitled to freedom.

Upon first reading, this argument seems sound. But suppose I told you Bruno was a serial killer. Suddenly the argument falls apart. Why? Because premise #1 begs the question against. Some people, like serial killers, should be denied freedom.

Page 9: Informal fallacies 2

1. Socialism is an unjust system of government.

2. Unjust systems of government must be

abolished.

3. Therefore socialism must be abolished.

Premise #1 here requires a lot more evidential support to escape begging the question against.

Page 10: Informal fallacies 2

Complex Question

Asks a question that can only be answered “yes” or “no,” but which assumes either:

1. That there is only one question when there are in fact two or more, each with its own answer, or

2. That some claim is true when in fact it is either false or, at the very least, doubtful.

Page 11: Informal fallacies 2

Have you stopped beating your wife yet?

This classic example illustrates the fallacy well. The question requires a yes or no answer, but neither answer would be correct (assuming you don’t beat your wife). The question also assumes something that is false (I hope), that you beat your wife.

Page 12: Informal fallacies 2

Does my opponent agree with the president’s disastrous economic policy which is now leading our nation to ruin?

Page 13: Informal fallacies 2

Do you support freedom and the right to bear arms?

Page 14: Informal fallacies 2

False alternatives

An argument commits the fallacy of false alternatives if and only if it offers in its premises a disjunction presenting two extreme alternatives as the only ones possible, when in reality there are one or more others equally plausible.

Page 15: Informal fallacies 2

There are only two possibilities: either our country abandons its involvement in foreign wars or it continues to interfere in other nations’ affairs. If it does the former, then it will become neutral like Switzerland, but if it does the latter, it’ll get deeper in debt to China. So our country will either become neutral like Switzerland or get deeper in debt to China.

Page 16: Informal fallacies 2

1.Either all U.S. universities will convert their

programs entirely into online courses, or they’ll all

soon go bankrupt.

2.U.S. universities will not convert their programs

entirely to online courses.

3.They’ll all soon go bankrupt.

Page 17: Informal fallacies 2

"It is with absolute frankness that we speak of this struggle of the proletariat; each man must choose between joining our side or the other side. Any attempt to avoid taking sides in this issue must end in fiasco.“

- Lenin

This is a classic false alternative fallacy. Either you subscribe completely to the Bolshevik party platform, or else you are an enemy.

Page 18: Informal fallacies 2

“Either you are with us, or you are with the terrorists.”

- George W Bush

“Every nation has to either be with us, or against us. Those who harbor terrorists, or who finance them, are going to pay a price.”

- Hillary Clinton

The false alternative fallacy is an extremely common one in politics.

Page 19: Informal fallacies 2

accident

The fallacy of accident is committed by an argument that treats a certain case as falling under a general rule or principle when in fact the case counts as an exception to it.

Page 20: Informal fallacies 2

1. Dogs are friendly animals

2. My Rottweiler, Otto, is a dog.

3. Otto is a friendly animal.

It’s generally true that dogs are friendly, but there are plenty of exceptions.

Page 21: Informal fallacies 2

1. Cutting people with a knife is a crime.

2. Surgeons cut people with knives.

3. Surgeons are criminals.

Again, it’s usually a bad thing to cut people with knives, but there are exceptions.