1. Common Logical Fallacies
Beware of weak arguments!
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2. An “argument” is not a fight.
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3. Argument = making a point about a subject and supporting it with evidence.
Attorneys make many arguments
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4. An argument can be supported with 3 types of evidence…
Logic
Ethics
Emotions
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5. An argument can be supported by...
Logic (logos):
Facts
Statistics
Expert testimony
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6. An argument can be supported by...
Ethics (ethos)
an appeal to one's sense of right and wrong or fairness
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7. An argument can be supported by...
Emotions (pathos)
an appeal to one’s patriotism, fears, or sympathies.
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8. Weak arguments rely on illogical statements called fallacies.
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9. The Fallacies
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10. False Dichotomy (aka Black and white thinking) “Either-Or fallacy”
Logical Fallacies
False Dichotomy (aka Black and white thinking) “Either-Or fallacy”
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11. False Dichotomy
Presents the false assumption that there are only two possibilities.
Sometimes called the “Either/Or” fallacy.
No other choices!
This
That or
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12. False Dichotomy
Most situations provide more than two possible outcomes.
College
Tech school
Intern
Travel
Military
Volunteer
Job
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13. False Dichotomy
Either you support sending more troops to the Middle East or you are America’s enemy. or
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14. False Dichotomy
“If you don’t drive this car, you might as well not drive at all.”
So it’s this or the bus?
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15. False Dichotomy here poverty
“You can either stay at your current job or quit and live in poverty.”
This is better than poverty…I guess.
here
poverty
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16. Logical Fallacies
Circular Reasoning
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17. …repeats an idea rather than giving a valid reason.
Circular Reasoning
…repeats an idea rather than giving a valid reason.
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18. Circular Reasoning
Martha is a good supervisor because she supervises personnel effectively.
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19. Circular Reasoning
The politician was truthful because he told us he always tells the truth.
I wouldn’t lie about telling the truth!!
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20. Logical Fallacies
Overgeneralization
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21. Overgeneralization
An overgeneralization draws a conclusion about an entire group, based on insufficient evidence.
Chihuahuas just want to trip people!
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22. Overgeneralization Stereotypes are one kind of overgeneralization.
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23. Overgeneralization
“I know several bald musicians. Bald men must be musically talented.”
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24. Overgeneralization
“Every time I’ve been to Florida, the weather has been rainy. It’s always raining in Florida!”
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25. Overgeneralization
“My mother, sister, and girlfriend diet all the time. Women are always on a diet!!”
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26. Post hoc Reasoning “Black cat reasoning”
Logical Fallacies
Post hoc Reasoning “Black cat reasoning”
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27. The full name of this fallacy is: “Post Hoc Ergo Propter Hoc”
Post hoc Reasoning
The full name of this fallacy is:
“Post Hoc Ergo Propter Hoc”
After this;
therefore,
because of this
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28. Post hoc Reasoning
After a black cat crossed my path, I failed my math test. That cat caused me to fail!!
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29. This fallacy is also known as:
Post hoc Reasoning
This fallacy is also known as:
False Cause
Questionable Cause
Mistaking Coincidence for Cause
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30. Post hoc Reasoning
He was listening to rap music before robbing the bank. The rap music caused him to commit the crime!
a-ha! Rap music again!!
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31. Appeal to the Crowd (aka Bandwagon)
Logical Fallacies
Appeal to the Crowd (aka Bandwagon)
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32. 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.
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33. Appeal to the Crowd
“Millions of people believe in astrology, so there must be some truth to it.”
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34. Appeal to the Crowd
“All I can say is that if enjoying junk food is unhealthy, then most of us are unhealthy!”
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35. Appeal to the Crowd
Speeding is not all that bad because everyone does it.
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36. Appeal to the Crowd
“Of course you want our payment plan; everybody takes advantage of that!”
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37. Logical Fallacies
Ad Hominem “To the man”
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38. Ad Hominem (to the man)
This weak argument focuses attention on people rather than on arguments or evidence.
It attacks the person rather than the issue.
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39. Ad Hominem (to the man)
Sam is out of shape… he will make a terrible mayor!
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40. Ad Hominem (to the man)
Mr. Spock is not an effective second-in- command because he has ugly pointed ears.
Ugly!! And pointed!!
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41. Ad Hominem (to the man)
Dr. Keen’s theories about plant genetics are worthless because she’s a compulsive shopper!
The plants know nothing about it!!
She spent thousands!!
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42. Logical Fallacies
Straw-Man Argument
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43. 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!!
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44. Straw-Man Argument
This argument simply ignores a person's actual position and substitutes a distorted, exaggerated or misrepresented version of that position.
This guy wants to STARVE our children!!
“The school lunch budget must be examined to cut out waste.”
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45. Straw-Man Argument
The Straw-man argument attempts to "prove" a point by overstating, exaggerating, or over-simplifying the arguments of the opposing side.
We will have to delay purchasing new cheerleading uniforms.
He wants to see our cheerleaders naked!
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46. Logical Fallacies
Appeal To Tradition
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47. 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.”
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48. Appeal To Tradition:
...This fallacy says
“We shouldn't challenge time-honored customs or traditions.”
“Don't rock the boat”
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49. 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!!!!
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50. Appeal To Tradition: “Tradition” is not always good.
Women have never voted! Why change tradition?
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51. Appeal To Tradition:
“Tradition” is not always good.
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52. Appeal To Tradition: “Tradition” is not always good. Click for next 
My family has always cooked in lard, so why break tradition?
I love lard!!
I used lard!
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53. Many more logical fallacies exist...
Be on the lookout for them in all of your reading and research!
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