Monday, February 16, 2015

Common Errors of Reasoning

lsat logical-reasoning logic

Here is a collection of the common logical fallacies

#. Sufficiency. Confusing weakening an argument in support of a given conclusion with proving the conclusion itself to be false. Treating evidence showing mere plausibility as if it proves that the conclusion is in fact true.

"Some historians claim that a lengthy drought preceded the fall of the Aztec empire. But we know from Aztec writings that in at least one year during the supposed drought there was minor flooding. Thus, the claim that there was a lengthy drought prior to the fall of the Aztec empire is false."

"We know that the defendant was in the vicinity of the robbery when the robbery occurred. Therefore, the defendant is guilty of the robbery"

#. Internal Contradiction: Making conflicting statements.

"Everyone should join our country club. After all, it's an exclusive group that links many of the influential members of the community."

1. Ad Hominem: Attacking a person or their character rather than making a claim based on reasoning.

2. Adedote: Using a personal or isolated experience as compelling and worthwhile evidence; suggesting that a personal or unique experience can be applied to other circumstances

3. Appeal to Ignorance: Using human ignorance or the inability to prove something in order make a claim.

4. Appeal to Tradition: Using tradition or cultural belief to suggest that something is true or accurate; suggesting that, because something has long been done in a certain way, it must be the correct way.

5. Appeal to Consequences: Concluding that a premise is either true or false base on what the consequence of that premise would be.

6. Argumentum ad Baculum: Making an argument by inciting fear or making threat.

7. Argumentum ad Ignorantiam: Relying a person's or group of people's ignorance to make a claim; misleading a person or group by appealing to their lack of knowledge in a particular topic.

8. Argumentum ad Populum: Attempting to sway popular support by appealing to sentimental weakness rather than with facts to reason.

9. Badwagon: Claiming something to be true or accurate simply because most people believe it to be true or accurate.

10. Begging the question: Making a claim that uses a tacit or implied assumption; raises a question by assuming an answer or shared belief.

11. Black or White: Suggesting only two alternate conclusions exist when, in reality, several possibilities exist.

12. Cherry-pick: Cherry-picking a particular data set or collection of facts while ignoring others in order to make an argument that suits a particular purpose.

13. Circular Reasoning: Using evidence that hasn't been proven in order to prove something else, then using that something else to prove the original claim.

14. Composition: Making erroneous conclusions about the composition of a whole or part of something.

15. Confirmation Bias: Making an argument that relies heavily on a personal bias.

16. Confusion of Correlation and Causation: Making claims about the cause of something simply because there exists a correlation between two things.

17. Exclude Middle: Considering only the extremes in any argument and ignoring the possibilities that exist in between.

18. Half Truth: Intentionally misleading a person to believe something by telling something that is, in fact, true, but leaving out important information.

19. Loaded Question: Asking a question that, if answered, will imply a shared agreement.

20. Misunderstanding Statistics: Making strange or erroneous claims about a particular idea by using statistics that have little or no ability to make such a claim.

21. Non Sequitur: "It does not follow". Making a conclusion that does not follow from previously established premises or conclusions.

"Some critics claim that scientific progress has increased the polarization of society and alienated large segments of the population. But these critics are wrong because even a cursory glance at the past shows that society is always somewhat polarized and some groups are inevitably alienated."

The author attempted to use the following premise:

"...society is always somewhat polarized and some groups are inevitably alienated."

to prove the following conclusion:

"...these critics [scientific progress has increased the polarization of society and alienated large segments of the population] are wrong."

The fact that such a situation has always existed does not disprove that scientific progress has increased the severity of the situation.

22. Omniscience: Using non-qualified statement to suggest ideas that imply "all" or "every" thing or situation.

"Two of my friends were shortchanged at that store. Therefore, everyone gets shortchanged at that store."

23. Post Hoc, Ergo Propter Hoc: "It happened after, so it was caused by." Suggesting that, because something previously happened that is related to an event, the previous happening caused the new event.

24. Failure to Prove Otherwise: Taking lack of evidence for a position to prove that position is false or taking lack of evidence against a position to prove that position is true. Instead of proving something to exist or be true, an arguer asks his/her opponent to prove that it doesn't exist.

"The White House has failed to offer any evidence that they have reached a trade agreement with China. Therefore no such agreement has been reached."

Instead of proving A (no agreement established), the author asks his/her opponent (the White House) to disprove A and draw the conclusion that A is true based on his/her opponent's failure of disproving A.

"There has been no evidence given against the existence of God, so God must exist."

25. Red Herring: Diverting attention by changing the subject.

26. Reification: Treating abstract or hypothetical things or ideas as concrete realities.

27. Slippery Slope: Arguing that a change in procedure, law, or action will create a domino-effect of adverse consequences, suggesting if one thing happens, a series of things will inevitably happen.

28. Small Number Statistics: Using an instance of a small fraction of the population to make an argument for the greater population.

29. Straw Man: Concocting a false or made up scenario and then attacking that scenario in order to make an opponent look bad.

30. Tu Quoque: Avoiding engagement with another's arugment by arguing something unrelated in return.