Logic Fallacies

1. Logic Fallacies Presented by Trisha Cummings

2. Fallacies • Fallacies are types of errors in reasoning. • They are most likely to happen when people get overly emotional about an issue. • In the heat of the moment they can seem persuasive and correct, but they are errors in reasoning and they do not reliably lead to the truth. • You want to be on the lookout for them when considering arguments, asking questions, listening to answers, writing papers or having an active discussion with someone.

3. Ad Hominem Fallacy • Attack the person rather than the statement . • Ad hominem abusive • Belittling or insulting the person • Candidate Jane's proposal about zoning is ridiculous. • She was caught cheating on her taxes in 2003. • Ad hominem circumstantial • Someone is in a circumstance that he is disposed to take a particular position • "What do you know about politics? You're too young to vote!"

4. Ad hominem tuquoque • Refers to a claim that the source making the argument has spoken or acted in a way inconsistent with the argument. • You too. • You say that stealing is wrong, but you do it as well • Inverse ad hominem • Praises a source in order to add support for that source's argument or claim • "Elizabeth has never told a lie in her entire life, and she says she saw him take the bag. She must be telling the truth.“ • What if Elizabeth is visually impaired?

5. Fallacy of the False Cause • Identifying an improper or unrelated cause for an observed effect – after this, therefore because of this • We draw conclusions based on our knowledge of the world and how it operates.  • Example - when dark clouds roll across the horizon, we can conclude that it will rain very soon. Because we have seen this happen before. • However this can wrong – if you associate the wrong events • Two fellow classmates got sick right after science class; therefore, science class must have made them sick.”

6. Straw Man fallacy • This happens when a person simply ignores a person's actual position and substitutes a distorted, exaggerated or misrepresented version of that position. • Senator Jones says that we should not fund the attack submarine program. I disagree entirely. I can't understand why he wants to leave us defenseless like that."

7. Appeal to Ignorance • Appeals to ignorance and the burden of proof • Whatever has not been proved or disproved must be correct. • No one has ever proved that the Loch Ness Monster exists, so it must not exist." • "No one has ever proved that the Loch Ness Monster does not exist, so it must exist." • Burden of Proof • In general, it is up to the person making an argument to try to prove it

8. Appeal to Emotion • Using the manipulation of the recipient's emotions, rather than valid logic, to win an argument. • Appeal to consequences • The speaker points to the disagreeable consequences of holding a particular belief in order to show that this belief is false. • You can't agree that evolution is true, because if it were, then we would be no better than monkeys and apes. • Appeal to fear • Attempts to create support for his or her idea by using deception and propaganda in attempts to increase fear and prejudice toward a competitor • You know, Professor Cummings, I really need to get an A in this class. I'd like to stop by during your office hours later to discuss my grade. I'll be in your building anyways, visiting my father. He's your dean, by the way. I'll see you later."

9. Appeal to flattery • A person uses flattery, excessive compliments, in an attempt to win support for their side. • Surely a man as smart as you can see this is a brilliant proposal." (failing to accept the proposal is a tacit admission of stupidity) • Appeal to pity • Tries to win support for their argument or idea by exploiting her or his opponent's feelings of pity or guilt. • You must have graded my exam incorrectly. I studied very hard for weeks specifically because I knew my career depended on getting a good grade. If you give me a failing grade I'm ruined!"

10. Appeal to ridicule • Which presents the opponent's argument in a way that appears ridiculous • It's funny you think you know so much about money, even though you're not an economist. • Appeal to spite • attempts to win favor for an argument by exploiting existing feelings of bitterness, or spite • "If you vote for this tax cut, it will mean that the fat cats will get even more money to spend on their expensive luxury yachts, while you and I keep struggling to pay the bills."

11. Wishful thinking • The formation of beliefs and making decisions according to what might be pleasing to imagine instead of by appealing to evidence or rationality • I want this to be true. Therefore, this is true.

12. Slippery Slope • The person asserts that some event must inevitably follow from another without any argument for the inevitability of the event in question. • Usually there are a series of steps or gradations between one event and the one in question and no reason is given as to why the intervening steps or gradations will simply be bypassed. • We have to stop the tuition increase! The next thing you know, they'll be charging $40,000 a semester!"

13. Fallacy of Equivocation • a single term is used with two or more meanings in the same argument. • It is well known that the average family has 2.5 children (premise #1). • Well, Jane's family is very average (premise #2) • So Jane’s family must have 2.5 children (conclusion).

14. Appeal to Popularity • The basic idea is that a claim is accepted as being true simply because most people are favorably inclined towards the claim. • The fact that most people have favorable emotions associated with the claim is substituted in place of actual evidence for the claim. • A person falls prey to this fallacy if he accepts a claim as being true simply because most other people approve of the claim. • I read the other day that most people really like the new gun control laws. • I was sort of suspicious of them, but I guess if most people like them, then they must be okay." • Mom’s favorite – • If everyone jumped of a cliff – would you?

15. Appeal to Tradition • This is right because we've always done it this way. • An appeal to tradition essentially makes two assumptions: • The old way of thinking was proven correct when introduced. • The truth could well be — the tradition might be entirely based on incorrect grounds. • The past justifications for the tradition are still valid at present. In cases where circumstances have changed, this assumption may be false. • My father and his father before him polished wood this way. Don't tell me how to polish wood. • We've been doing this for thirty years, and we've never had problems with it. • The tradition in this town is to buy from local traders.

16. Resources • How to Ask a Smart Question - By S. Snyder(Last revised:11/19/03) http://faculty.gvc.edu/ssnyder/121/Goodquestions.html • http://en.wikipedia.org/wiki/Ad_Hominem • http://ksuweb.kennesaw.edu/~shagin/logfal-pbc-falsecause.htm • http://www.nizkor.org/features/fallacies/straw-man.html • http://info-pollution.com/ignorance.htm • http://www.fallacyfiles.org/wishthnk.html • http://atheism.about.com/library/FAQs/skepticism/blfaq_fall_equivocation.htm

17. http://en.wikipedia.org/wiki/Appeal_to_spite • http://en.wikipedia.org/wiki/Appeal_to_ridicule • http://en.wikipedia.org/wiki/Appeal_to_pity • http://en.wikipedia.org/wiki/Appeal_to_flattery • http://en.wikipedia.org/wiki/Appeal_to_fear • http://nizkor.org/features/fallacies/appeal-to-fear.html • http://www.nizkor.org/features/fallacies/slippery-slope.html • http://www.nizkor.org/features/fallacies/appeal-to-popularity.html • http://en.wikipedia.org/wiki/Appeal_to_tradition • http://www.changingminds.org/disciplines/argument/fallacies/appeal_tradition.htm