Informal Reasoning

FallaciesThe ten deadly fallacies

Ad Ignorantiam Claiming something is true because it cannot be proved to be false

Hasty generalization Generalizing from insufficient evidence

Post hoc ergo propter hoc Confusing a correlation with a casual connection

Ad hominem Attacking/supporting the person rather than the argument

Circular reasoning Assuming the truth of what you are supposed to be proving

Special pleading Using double standards to excuse an individual or group

Equivocation Using language ambiguously

False analogy Assuming that because two things are alike in some respects they are alike in other respects

False Dilemma Assuming the only two black and white alternatives exist

Loaded question A question that is biased because it contains a built-in assumption

Ad Ignorantiam: Something is true on the grounds that there is no evidence to

disprove it.

• The Communist witch hunt in the 1960’s• “ There is nothing in his files to say he is not a

communist”– Senator Joe McCarthy

Post hoc ergo propter hoc

• A follows B then B must be the cause of A• Murder rate goes up after the abolition of

capital punishment, therefore can we say that capital punishment is an effective deterrent

• It could be the case but we need more evidence

Smoking causes causes

Explain this• As the number of churches in American cities

increase so does the number of prostitutes!!!

Ad hominem

• You attack the supporters of an argument• You may have a vested interest in something

but that does not mean you cannot be fair.

Circular reasoning

• Assuming the truth in something you are supposed to be proving

• Page 126 in book

False Dilemma

• Assuming there are only 2 ways of solving something when there are other options

• Binary thinking• Pro life/ pro choice

Loaded Question

• Do you always cheat in exams

FallaciesThe ten deadly fallacies

Ad Ignorantiam Claiming something is true because it cannot be proved to be false

Hasty generalization Generalizing from insufficient evidence

Post hoc ergo propter hoc Confusing a correlation with a casual connection

Ad hominem Attacking/supporting the person rather than the argument

Circular reasoning Assuming the truth of what you are supposed to be proving

Special pleading Using double standards to excuse an individual or group

Equivocation Using language ambiguously

False analogy Assuming that because two things are alike in some respects they are alike in other respects

False Dilemma Assuming the only two black and white alternatives exist

Loaded question A question that is biased because it contains a built-in assumption