Five Common Thinking Errors

 

1. Non Sequitur= “it does not follow”; The conclusion does not follow logically from the premises used to support it.

i.e. Premise: There is a rock in my backyard

Premise: There are no tigers in my backyard

Conclusion: The rock keeps tigers away

The first premise says “backyard à rock”

The second premise says “backyard à no tigers”

The conclusion says “rock à no tigers”

The conclusion does not logically follow the premises used to

support it, so therefore it is a Non Sequitur.

 

2. False and/or Vague Premises= The conclusions do follow logically, but the premises are either vague or false, therefore the conclusion is untrue.

i.e. Premise: All people are Catholic

Premise: My dog is a person

Conclusion: My dog is Catholic

The first premise says “people à Catholic”

The second premise says “dog à person”

The conclusion says “dog à Catholic”

The conclusion logically follows the premises; however, the premises are false, so therefore the conclusion is false.

 

i.e. Premise: Men are fools

Premise: Albert Einstein was a man

Conclusion: Therefore Einstein was a fool

 

The first premise says “men à fools”

The second premise says “Einstein à man”

The conclusion says “Einstein à fool”

The conclusion logically follows the premises; however, the first premise is vague, so therefore the conclusion is false.

 

3. Ad Hominem= “against the person”; Instead of attacking a person’s argument, one attacks a certain quality in the person which is not directly related to the argument itself.

 

i.e. Premise: William Bennett preaches the necessity of virtues

Premise: William Bennett is rich, anti-gay, anti-choice, etc.

Conclusion: William Bennett is wrong.

 

The second premise does necessarily mean that Bennett’s preaching of virtues is wrong and it attacks his personal qualities, so therefore the argument is an Ad Hominem.

 

4. Begging the Question= “petition principii”; Trying to demonstrate that a certain point is true, but in the process already assuming that the point is true.

 

i.e. “I believe that God exists because He created us.”

“He” is a pronoun for God, so the speaker is essentially saying

“I believe God exists because God created us.” For God to

have created us he must exist, though, so therefore the speaker is begging the question.

 

5. Red Herring= Saying something inflammatory or beside-the-point in order to distract everyone from the real issue.

i.e. "You may claim that the death penalty is an ineffective deterrent against crime -- but what about the victims of crime? How do you think surviving family members feel when they see the man who murdered their son kept in prison at their expense? Is it right that they should pay for their son's murderer to be fed and housed?"

Instead of attacking the belief that the death penalty is an “ineffective deterrent” against crime, the speaker instead brings up the more emotionally charged issue of how the victim’s relatives would feel, which does not address whether it is a “deterrent” against crime.