Common Logical Fallacies Beware of weak arguments! Argument

Common Logical Fallacies Beware of weak arguments! Argument

Common Logical Fallacies Beware of weak arguments! Argument An argument is not a fight. Argument

Argument = making a point about a subject and supporting it with evidence. Argument An argument can be supported with 3 types of evidence

1.Logic 2.Ethics 3.Emotions Argument An argument can be supported by... Logic (logos):

Facts Statistics Expert testimony Argument An argument can be supported by... Ethics

(ethos) an appeal to one's sense of right and wrong or good sense Argument

An argument can be supported by... Emotions (pathos) an appeal to ones patriotism, fears, or sympathies. Weak Arguments

Weak arguments rely on illogical statements called fallacies. The following slides contain examples of logical fallacies... The Fallacies Logical Fallacies

NON-SEQUITUR Non-SECK-quit-er aka: It does not follow Non-sequitur

("it does not follow") Non-SECK-quit-er An idea or conclusion that does not follow logically based upon the evidence.

Non-sequitur ("it does not follow") Example: The President graduated from Harvard. Therefore, he can't make mistakes.

perfect Non-sequitur ("it does not follow") The ocean is water. People must drink water to survive.

Therefore, people must drink the ocean to survive. Logical Fallacies BEGGING THE QUESTION Begging the Question

Basing an argument on an assumption that has not been proven or that is impossible to prove. Examples follow on the next few slides: Begging the Question

People who watch a lot of TV are less active than people who watch no TV Heres the argument being presented

because the major networks broadcast hidden waves to make people passive and lazy. Heres the assumption

thats not been proven Sleep waves zzzzz Wait Really??

Begging the Question The TV argument from the previous slide begs the question: How do you know the TV stations are broadcasting waves to make people sleepy?

zzzzz Begging the Question Evolution should not be taught in public schools

Heres the argument being presented because the theory of evolution comes directly from Satan.

Heres the assumption thats not been proven plague?.....no. Earthquake ?.....no. I knowEvolution!!

Wait Really?? Begging the Question The Evolution argument from the previous slide begs the question: How do you know the theory of

Evolution comes from Satan? Logical Fallacies Circular Reasoning Circular Reasoning

repeats an idea rather than giving a valid reason. Circular Reasoning Martha is a good supervisor because she supervises personnel effectively.

Circular Reasoning A publication is pornographic only if it contains pornography. How do I know if its pornographic?

Oh, youll know Circular Reasoning The politician was truthful because he told us he always tells the truth.

I wouldnt lie about telling the truth!! Logical Fallacies Straw-Man Argument

Straw-Man Argument Gives false characteristics to an argument and then attacks the argument based on those false characteristics. Just look at him!! He probably wants to take all your

money too!! Straw-Man Argument This argument simply ignores a person's actual position and substitutes a distorted, exaggerated or misrepresented version of that position. The school

lunch budget must be examined to cut out waste. This guy wants to STARVE our

children!! Straw-Man Argument The Straw-man argument attempts to "prove" a point by overstating, exaggerating, or oversimplifying the arguments of the opposing side. Clearly, this guy wants to bleed

taxpayers dry with these increases! Logical Fallacies Ad Hominem aka To the man

Ad Hominem (to the man) This argument focuses attention on people rather than on arguments or evidence. It attacks the person rather than the issue.

Ad Hominem (to the man) Example: Sam is out of shape, so how can he be an effective

mayor? Ad Hominem (to the man) Example:

Mr. Spock is not an effective second-in- command because he has ugly pointed ears. Ugly!! And pointed!! Ad Hominem

(to the man) Examples: Dr. Kirkegards books about plant genetics are worthless because she was caught shoplifting.

The plants know nothing about it!! Stolen merchandise Logical Fallacies Overgeneralization

Overgeneralization An overgeneralization draws a conclusion about an entire group, topic, or place based on insufficient evidence. Stereotypes are one kind of overgeneralization.

Overgeneralization Example: I know several bald musicians. Bald men must be musically talented.

Overgeneralization Example: Every time Ive been to Florida, the weather has been rainy. Its always raining in Florida! Overgeneralization

Example: My mother, sister, and girlfriend diet all the time. Women are always on a diet!! Logical Fallacies

POST HOC REASONING aka: Black cat syndrome Post hoc Reasoning The full name of this fallacy is: Post Hoc Ergo Propter Hoc

After this; therefore, because of this After a black cat crossed my path, I failed my

math test. That cat caused me to fail!! Post hoc Reasoning This fallacy is also known as: False Cause Questionable Cause Mistaking Coincidence for Cause

Post hoc Reasoning Example: He was listening to rap music before robbing the bank. The rap music caused him to commit the crime! Rap music

again!! Logical Fallacies FALSE DICHOTOMY aka: Either-or fallacy False Dichotomy

Presents the false assumption that there are only two possibilities. Sometimes called the Either/Or fallacy. Most situations provide more than two possible outcomes. False Dichotomy

Examples: Either you support sending more troops to the Middle East or you are Americas enemy. False Dichotomy Example:

If you dont drive this car, you might as well not drive at all. So its this or the bus? False Dichotomy

Example: You can either stay at your current job or quit and live in poverty. This is better than povertyI guess.

Logical Fallacies RED HERRING Red Herring ...named after a strong-smelling fish, the scent of which throws hounds off the scent of a trail.

The Red Herring occurs when one changes the subject to draw attention away from the main issue. The focus is shifted to a side issue or something irrelevant. Red Herring Example:

Youre a vegetarian because you disagree with killing animals? So then how can you support abortion rights? Abortion and vegetarianism are 2 different subjects, thats how!!

Red Herring Example: "I work 60 hours a week to support my family, and I pay my taxes; you shouldn't arrest me just because I drove a little drunk! Nice try, but I recognize a red

herring when I hear one. Red Herring Red Herring Why did your company dump

toxic chemicals in the river? Youre not looking at the big picture. Our company helps citizens with jobs and charity drives. We even

provide college scholarships for local students! Logical Fallacies APPEAL TO THE CROWD

Appeal to the Crowd argumentum ad populum relying on the emotional passion of the crowd in making an argument; playing on a group's fears or prejudices.

Appeal to the Crowd Example: Millions of people believe in astrology, so there must be some truth to it. Appeal to the Crowd

All I can say is that if enjoying junk food is unhealthy, then most of us are unhealthy! Appeal to the Crowd Speeding is not all that bad because everyone does it.

Appeal to the Crowd Of course you want our payment plan; everybody takes advantage of that! Logical Fallacies APPEAL TO TRADITION

Appeal To Tradition: This argument says something is good or correct because it is a tradition. In other words We should continue to do things as they have been done in the past.

Appeal To Tradition: ...This fallacy says We shouldn't challenge time-honored customs or traditions. Don't rock the boat Appeal To Tradition:

Of course you have to play Here Comes the Bride at your wedding, because that's always been the song that is played. But I hate that song!!!!

Appeal To Tradition: Women have never voted! Why change tradition? Tradition is not always good.

Appeal To Tradition: Tradition is not always good. Appeal To Tradition: Tradition is not always good. My family has always cooked

in lard, so why break tradition? I love lard!! I used lard!

Many more logical fallacies exist... Be on the lookout for them in all of your reading and research! End of Presentation.

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