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Lecture 4:
Logical Fallacies

Sometimes, people will use reasoning to try to convince you which is flawed or false because it violates the rules of logic. There are many ways to violate rules of logic; they are called "logical fallacies." There are dozens of logical fallacies. Listed below, with examples, are only a few. Once you start looking for them, you will find them everywhere: in politics, in advertising, even in your own thinking. We all fall prey to these fallacies once in a while, but being conscious of them can make us less vulnerable.

Equivocation occurs when a word has one meaning in one part of the argument and another meaning in another part. Examples:

• This is supposed to be a free country, but nothing worth having is ever free.
• All banks are beside rivers. Therefore, the financial institution where I deposit my money is beside a river.
• Sure philosophy helps you argue better, but do we really need to encourage people to argue? There's enough hostility in this world.
• Marriage is a fine institution, but I'm not ready for an institution. -- Mae West

Non Sequitur occurs when the conclusion does not follow from the claim. Examples:

• He went to the movies on three consecutive nights, so he must love movies.
• Megan drives an expensive car, so she must be making a lot of money.
• I read about a pitbull attack. My neighbor owns a pitbull. My life is in danger.
• Suppose you were an idiot, and suppose you were a member of Congress; but I repeat myself.-- Mark Twain

Post Hoc, Ergo Propter Hoc occurs when people assert that because two events occurred closely together in time, one event caused the other. Examples:

• I wore this shirt, and we won the game. Therefore, if I wear this shirt, we'll win the game.
• Most people who are read the last rites die shortly afterwards. Priests are going around killing people with magic words!
• John was in my office. Later, I found money missing from my office. John must have taken it.
• Every time I go camping, it rains. All I have to do to make it rain is put up a tent!

Hasty generalization occurs when people assume that because one or two examples are true, all similar examples are true. Examples:

• I ordered a shirt online and it was too small, so I never order clothes online anymore-they're always too small.
• You and I can't speak French, and we go to Harbor College. So nobody at Harbor College speaks French.
• I was in Seattle for three days and it was sunny the whole time. It hardly ever rains there.
• All generalizations are false, including this one. -- Mark Twain

Slippery Slope occurs when a person argues that a whole course of actions will inevitably result from one action. The argument is that once you allow one thing, a whole flood of other, disastrous, things are sure to follow. Usually this argument is made without any evidence to show that those other disastrous things will actually follow. Examples:

• If we allow gay marriage, there is nothing to stop polygamy. And once we allow this, where will it stop? Will we have to legalize incest or bestiality?
• If you allow the students to redo this test, they are going to want to redo every assignment for the rest of the year.
• We can't permit the sale of marijuana by doctor's prescription, because that will lead people to believe it's an acceptable drug; this will open the floodgates to the complete legalization of all drugs for use by everyone.
• Today, women want the vote. Tomorrow, they'll want to be doctors and lawyers, and then combat soldiers. Give them that, and before long, they'll insist on taking the initiative in sex. If you want to protect the very meaning of masculinity, you must deny them suffrage.

False Analogy occurs when you use an analogy to make a point. An analogy is a comparison between two similar items. Analogies can be useful, but their weakness is that two things are never really the same. False analogy occurs when the two things being compared appear similar but are really very different. Examples:

• No one objects to a physician looking up a difficult case in medical books. Why, then, shouldn't students taking a difficult examination be permitted to use their textbooks?
• People who have to have a cup of coffee every morning before they can function have no less a problem than alcoholics who have to have their alcohol each day to sustain them.
• Making people register their own guns is like the Nazis making the Jews register with their government. This policy is crazy.
• Employees are like nails. Just as nails must be hit in the head in order to make them work, so must employees.

Straw Man occurs when a person creates a weak, oversimplified, or exaggerated version of his opponent's argument, refutes it, and then says he has proven his opponent's argument wrong. Examples:

• After Will said that we should put more money into health and education, Warren responded by saying that he was surprised that Will hates our country so much that he wants to leave it defenseless by cutting military spending.
• Some people think we should have publicly funded healthcare, but in this age of government spending run amok, the last thing we need is another entitlement.
• Child: Can I go to the movies with my friends?
  Parent: Not tonight, you haven't finished your chores.
  Child: Ugh! You'll never let me do anything fun with my friends.
• Person 1: I think pollution from humans contributes to climate change.
  Person 2: So, you think humans are directly responsible for extreme weather, like hurricanes, and have caused
the droughts in the southwestern U.S.? If that's the case, maybe we just need to go to the southwest and perform a "rain dance."
• George supports a law reducing speed limits by 10 miles an hour. His opponent, Lucy, says, "This is part of your ultimate plan to get rid of all cars."

Begging the Question occurs when someone draws a conclusion based on a premise which actually needs proof. Here's a sample argument: Everything in the Bible is true. The Bible says that Noah built an ark. Therefore, Noah's Ark really existed. The problem with this argument is that "Everything in the Bible is true" has not been proven. The conclusion is based on a premise which needs to be proven. Examples:

• The death penalty is wrong because killing people is immoral.
• Ghosts are real because I have had experiences with them myself.
• Everyone wants the new iPhone because it is the hottest new gadget on the market!
• Prosecutor to defendant: So how did you feel when you killed your wife?

Either/Or occurs when a person says there are just two choices when in reality there are many more. Examples:

• You're either for me or you're against me!
• I can't believe you voted against building a wall along the southern border of the U.S. Either you're for protecting our borders or you aren't.
• We have to decide if we are going to support school choice or if we are going to support failing schools. Those are the only two options.
• You either support Hillary Clinton for President or you don't believe in women's rights.

Oversimplification occurs when it is assumed that there is a single, simple cause of an outcome or a problem when in reality there may be many causes or elements. Examples:

• School shootings are caused by violence in the media.
• School shootings are causerd by the easy availability of guns.
• Lead poisoning can contribute to violent behavior. Many inner city children have dangerous levels of lead in their blood. Therefore, violent crime in the inner city can be solved by curing the lead problem.
• Coach says that the reason his team won their last game is because the team had a high carbohydrate meal before the game.

Tu Quoque is Latin for "you too." Pronounced too-kwo-kwee. You avoided having to engage with criticism by turning it back on the accuser - you answered criticism with criticism. This fallacy is also known as the appeal to hypocrisy. It occurs when a person rejects an argument because the person making it doesn't follow his own advice. It's annoying when a person gives you advice he doesn't follow. But that doesn't mean his advice is bad. Examples:

• Nicole identified that Hannah had committed a logical fallacy, but instead of addressing the substance of her claim, Hannah accused Nicole of committing a fallacy earlier on in the conversation.
• Peter: "Based on the arguments I have presented, it is evident that it is morally wrong to use animals for food or clothing."
  Bill: "But you are wearing a leather jacket and you have a roast beef sandwich in your hand! How can you say that using animals for food and clothing is wrong?"
• The Romans kept slaves. Therefore we can keep slaves too.
• Person 1: 'You shouldn't smoke. It's bad for your health. I wish I'd never started.'
  Person 2: 'Didn't you always offer me cigarettes in the past?'

Appeal to Ignorance occurs when a person argues that his lack of evidence shouldn't invalidate his argument, because there's way to now what that evidence is. Examples:

• There's no way to know how many people have been deterred by the death penalty, so we shouldn't abolish the death penalty; we might be encouraging people to commit murder.
• There's no way to know how many innocent people have been wrongly convicted and executed, so we must abolish the death penalty.
• You know that scientists can't prove that UFO's do not visit the Earth, so it makes sense to believe in them.
• Although we have proven that the moon is not made of spare ribs, we have not proven that its core cannot be filled with them; therefore, the moon's core is filled with spare ribs.

Ad Hominem is Latin for "against the man." It occurs when an opponent attacks the person making an argument, rather than attacking the argument itself. This is common is political contests. Examples:

• Well, it's pretty obvious that your political party doesn't know how to be fiscally responsible, so I wouldn't expect you to, either.
• People like you don't understand what it's like to be of my race so you blatantly have no right to make an argument about this situation.
• Student: Hey, Professor Moore, we shouldn't have to read this book by Freud. Everyone knows he used cocaine.
• We cannot approve of this recycling idea. It was thought of by a bunch of hippie communist weirdos.

Appeal to Fear occurs when a person tries to persuade someone to do something by making them afraid of what will happen if they don't do it. It often looks like this: if you don't accept X as true, something terrible will happen to you. Therefore, X must be true. Examples:

• If we don't bail out the big automakers, the US economy will collapse. Therefore, we need to bail out the automakers.
• My mom is this school's biggest donor, so you should really reconsider that C you gave me on my latest paper.
• Barack Obama's support of the Dream Act will open our country to terrorism.
• Break-ins are 10 times more likely in homes that do not have security systems. Buy our security system if you want to keep your family safe!

Bandwagon occurs when someone tries to convince you to do something because "everyone else" is doing it. Examples:

• Officer, I didn't do anything wrong. Everyone else was speeding too!
• This book has been on the New York Times bestseller lists for 50 weeks. It must be good.
• Marcus wants to go to a small community college close to home, but most of the kids in his class are applying to larger colleges out of state. Marcus decides that he should also apply to those colleges.
• 9 out of 10 people drink beer. You should drink it too, or you won't be popular.