1.      Person A makes claim X.

2.      Person B makes an attack on person A.

3.      Therefore A's claim is false.

The reason why an Ad Hominem (of any kind) is a fallacy is that the character, circumstances, or actions of a person do not (in most cases) have a bearing on the truth or falsity of the claim being made (or the quality of the argument being made).

Example of Ad Hominem

1.      Bill: "I believe that abortion is morally wrong."
Dave: "Of course you would say that, you're a priest."
Bill: "What about the arguments I gave to support my position?"
Dave: "Those don't count. Like I said, you're a priest, so you have to say that abortion is wrong. Further, you are just a lackey to the Pope, so I can't believe what you say."

1.      Person A makes claim X.

2.      Person B asserts that A's actions or past claims are inconsistent with the truth of claim X.

3.      Therefore X is false.

The fact that a person makes inconsistent claims does not make any particular claim he makes false (although of any pair of inconsistent claims only one can be true - but both can be false). Also, the fact that a person's claims are not consistent with his actions might indicate that the person is a hypocrite but this does not prove his claims are false.

Examples of Ad Hominem Tu Quoque

1.      Bill: "Smoking is very unhealthy and leads to all sorts of problems. So take my advice and never start."
Jill: "Well, I certainly don't want to get cancer."
Bill: "I'm going to get a smoke. Want to join me Dave?"
Jill: "Well, I guess smoking can't be that bad. After all, Bill smokes."

2. Jill: "I think the gun control bill shouldn't be supported because it won't be effective and will waste money."
   Bill: "Well, just last month you supported the bill. So I guess you're wrong now."
3. 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!"

Examples of Appeal to Authority

1.      Bill and Jane are arguing about the morality of abortion:

Bill: "I believe that abortion is morally acceptable. After all, a woman should have a right to her own body."
Jane: "I disagree completely. Dr. Johan Skarn says that abortion is always morally wrong, regardless of the situation. He has to be right, after all, he is a respected expert in his field."
Bill: "I've never heard of Dr. Skarn. Who is he?"
Jane: "He's the guy that won the Nobel Prize in physics for his work on cold fusion."
Bill: "I see. Does he have any expertise in morality or ethics?"
Jane: "I don't know. But he's a world famous expert, so I believe him."

2. Dave and Kintaro are arguing about Stalin's reign in the Soviet Union. Dave has been arguing that Stalin was a great leader while Kintaro disagrees with him.

Kintaro: "I don't see how you can consider Stalin to be a great leader. He killed millions of his own people, he crippled the Soviet economy, kept most of the people in fear and laid the foundations for the violence that is occuring in much of Eastern Europe."
Dave: "Yeah, well you say that. However, I have a book at home that says that Stalin was acting in the best interest of the people. The millions that were killed were vicious enemies of the state and they had to be killed to protect the rest of the peaceful citizens. This book lays it all out, so it has to be true."

3. I'm not a doctor, but I play one on the hit series "Bimbos and Studmuffins in the OR." You can take it from me that when you need a fast acting, effective and safe pain killer there is nothing better than MorphiDope 2000. That is my considered medical opinion.
4. Siphwe and Sasha are having a conversation:

Sasha: "I played the lottery today and I know I am going to win something."
Siphwe: "What did you do, rig the outcome?"
Sasha: "No, silly. I called my Super Psychic Buddy at the 1-900-MindPower number. After consulting his magic Californian Tarot deck, he told me my lucky numbers."
Siphwe: "And you believed him?"
Sasha: "Certainly, he is a certified Californian Master-Mind Psychic. That is why I believe what he has to say. I mean, like, who else would know what my lucky numbers are?"

Appeal to Belief is a fallacy that has this general pattern:

1.      Most people believe that a claim, X, is true.

2.      Therefore X is true.

This line of "reasoning" is fallacious because the fact that many people believe a claim does not, in general, serve as evidence that the claim is true.

There are, however, some cases when the fact that many people accept a claim as true is an indication that it is true. For example, while you are visiting Maine, you are told by several people that they believe that people older than 16 need to buy a fishing license in order to fish. Barring reasons to doubt these people, their statements give you reason to believe that anyone over 16 will need to buy a fishing license.

There are also cases in which what people believe actually determines the truth of a claim. For example, the truth of claims about manners and proper behavior might simply depend on what people believe to be good manners and proper behavior. Another example is the case of community standards, which are often taken to be the standards that most people accept. In some cases, what violates certain community standards is taken to be obscene. In such cases, for the claim "x is obscene" to be true is for most people in that community to believe that x is obscene. In such cases it is still prudent to question the justification of the individual beliefs.

 Examples of Appeal to General Belief

1.      At one time, most people in Europe believed that the earth was the center of the solar system (at least most of those who had beliefs about such things). However, this belief turned out to be false.

2. God must exist. After all, I just saw a poll that says 85% of all Americans believe in God.
3. Of course there is nothing wrong with drinking. Ask anyone, he'll tell you that he thinks drinking is just fine.

An Appeal to Emotion is a fallacy with the following structure:

1.      Favorable emotions are associated with X.

2.      Therefore Appeal to Emotion, X is true.

An is a fallacy with the following structure:

1.      Favorable emotions are associated with X.

2.      Therefore, X is true.

The Appeal to Popularity has the following form:

1.      Most people approve of X (have favorable emotions towards X).

2.      Therefore X is true.

Examples of Appeal to Popularity

1.      "My fellow Americans...there has been some talk that the government is overstepping its bounds by allowing police to enter peoples' homes without the warrants traditionally required by the Constitution. However, these are dangerous times and dangerous times require appropriate actions. I have in my office thousands of letters from people who let me know, in no uncertain terms, that they heartily endorse the war against crime in these United States. Because of this overwhelming approval, it is evident that the police are doing the right thing."

2. "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."
3. Jill and Jane have some concerns that the rules their sorority has set are racist in character. Since Jill is a decent person, she brings her concerns up in the next meeting. The president of the sorority assures her that there is nothing wrong with the rules, since the majority of the sisters like them. Jane accepts this ruling but Jill decides to leave the sorority.

Description of Begging the Question

Begging the Question is a fallacy in which the premises include the claim that the conclusion is true or (directly or indirectly) assume that the conclusion is true. This sort of "reasoning" typically has the following form.

1.      Premises in which the truth of the conclusion is claimed or the truth of the conclusion is assumed (either directly or indirectly).

2.      Claim C (the conclusion) is true.  

Examples of Begging the Question

1.      Bill: "God must exist."
Jill: "How do you know."
Bill: "Because the Bible says so."
Jill: "Why should I believe the Bible?"
Bill: "Because the Bible was written by God."

2. "If such actions were not illegal, then they would not be prohibited by the law."
3. "The belief in God is universal. After all, everyone believes in God."
4. Interviewer: "Your resume looks impressive but I need another reference."
   Bill: "Jill can give me a good reference."
   Interviewer: "Good. But how do I know that Jill is trustworthy?"
   Bill: "Certainly. I can vouch for her."

Examples of Hasty Generalization (through a biased sample)

1.      Bill is assigned by his editor to determine what most Americans think about a new law that will place a federal tax on all modems and computers purchased. The revenues from the tax will be used to enforce new online decency laws. Bill, being technically inclined, decides to use an email poll. In his poll, 95% of those surveyed opposed the tax. Bill was quite surprised when 65% of all Americans voted for the taxes.

2. The United Pacifists of America decide to run a poll to determine what Americans think about guns and gun control. Jane is assigned the task of setting up the study. To save mailing costs, she includes the survey form in the group's newsletter mailing. She is very pleased to find out that 95% of those surveyed favor gun control laws and she tells her friends that the vast majority of Americans favor gun control laws.
3. Large scale polls were taken in Florida, California, and Maine and it was found that an average of 55% of those polled spent at least fourteen days a year near the ocean. So, it can be safely concluded that 55% of all Americans spend at least fourteen days near the ocean each year.

Description of Post Hoc

A Post Hoc is a fallacy with the following form:

1.      A occurs before B.

Examples of Post Hoc

1.      I had been doing pretty poorly this season. Then my girlfriend gave me this neon laces for my spikes and I won my next three races. Those laces must be good luck...if I keep on wearing them I can't help but win!

2. Bill purchases a new PowerMac and it works fine for months. He then buys and installs a new piece of software. The next time he starts up his Mac, it freezes. Bill concludes that the software must be the cause of the freeze.
3. Joan is scratched by a cat while visiting her friend. Two days later she comes down with a fever. Joan concludes that the cat's scratch must be the cause of her illness.
4. The Republicans pass a new tax reform law that benefits wealthly Americans. Shortly thereafter the economy takes a nose dive. The Democrats claim that the the tax reform caused the economic woes and they push to get rid of it.
5. The picture on Jim's old TV set goes out of focus. Jim goes over and strikes the TV soundly on the side and the picture goes back into focus. Jim tells his friend that hitting the TV fixed it.
6. Jane gets a rather large wart on her finger. Based on a story her father told her, she cuts a potato in half, rubs it on the wart and then buries it under the light of a full moon. Over the next month her wart shrinks and eventually vanishes. Jane writes her father to tell him how right he was about the cure.

Description of False Dilemma

A False Dilemma is a fallacy in which a person uses the following pattern of "reasoning":

1.      Either claim X is true or claim Y is true (when X and Y could both be false).

2.      Claim Y is false.

3.      Therefore claim X is true.

This line of "reasoning" is fallacious because if both claims could be false, then it cannot be inferred that one is true because the other is false. That this is the case is made clear by the following example:

1.      Either 1+1=4 or 1+1=12.

2.      It is not the case that 1+1=4.

3.      Therefore 1+1=12.

In cases in which the two options are, in fact, the only two options, this line of reasoning is not fallacious. For example:

1.      Bill is dead or he is alive.

2.      Bill is not dead.

3.      Therefore Bill is alive.

Examples of False Dilemma

1.      Senator Jill: "We'll have to cut education funding this year."
Senator Bill: "Why?"
Senator Jill: "Well, either we cut the social programs or we live with a huge deficit and we can't live with the deficit."

2. Bill: "Jill and I both support having prayer in public schools."
   Jill: "Hey, I never said that!"
   Bill: "You're not an atheist are you Jill?"
3. "Look, you are going to have to make up your mind. Either you decide that you can afford this stereo, or you decide you are going to do without music for a while."

Description of Gambler's Fallacy

The Gambler's Fallacy is committed when a person assumes that a departure from what occurs on average or in the long term will be corrected in the short term. The form of the fallacy is as follows:

1.      X has happened.

2.      X departs from what is expected to occur on average or over the long term.

3.      Therefore, X will come to an end soon.  

Examples of Gambler's Fallacy

1.      Bill is playing against Doug in a WWII tank battle game. Doug has had a great "streak of luck" and has been killing Bill's tanks left and right with good die rolls. Bill, who has a few tanks left, decides to risk all in a desperate attack on Doug. He is a bit worried that Doug might wipe him out, but he thinks that since Doug's luck at rolling has been great Doug must be due for some bad dice rolls. Bill launches his attack and Doug butchers his forces.

2. Jane and Bill are talking:

Jane: "I'll be able to buy that car I always wanted soon."
Bill: "Why, did you get a raise?"
Jane: "No. But you know how I've been playing the lottery all these years?"
Bill: "Yes, you buy a ticket for every drawing, without fail."
Jane: "And I've lost every time."
Bill: "So why do you think you will win this time?"
Jane: "Well, after all those losses I'm due for a win."

3. Joe and Sam are at the race track betting on horses.

Joe: "You see that horse over there? He lost his last four races. I'm going to bet on him."
Sam: "Why? I think he will probably lose."
Joe: "No way, Sam. I looked up the horse's stats and he has won half his races in the past two years. Since he has lost three of his last four races, he'll have to win this race. So I'm betting the farm on him."
Sam: "Are you sure?"
Joe: "Of course I'm sure. That pony is due, man...he's due!"

Description of Hasty Generalization

This fallacy is committed when a person draws a conclusion about a population based on a sample that is not large enough. It has the following form:

1.      Sample S, which is too small, is taken from population P.

2.      Conclusion C is drawn about Population P based on S.

Examples of Hasty Generalization

1.      Smith, who is from England, decides to attend graduate school at Ohio State University. He has never been to the US before. The day after he arrives, he is walking back from an orientation session and sees two white (albino) squirrels chasing each other around a tree. In his next letter home, he tells his family that American squirrels are white.

2. Sam is riding her bike in her home town in Maine, minding her own business. A station wagon comes up behind her and the driver starts beeping his horn and then tries to force her off the road. As he goes by, the driver yells "get on the sidewalk where you belong!" Sam sees that the car has Ohio plates and concludes that all Ohio drivers are jerks.
3. Bill: "You know, those feminists all hate men."
   Joe: "Really?"
   Bill: "Yeah. I was in my philosophy class the other day and that Rachel chick gave a presentation."
   Joe: "Which Rachel?"
   Bill: "You know her. She's the one that runs that feminist group over at the Women's Center. She said that men are all sexist pigs. I asked her why she believed this and she said that her last few boyfriends were real sexist pigs. "
   Joe: "That doesn't sound like a good reason to believe that all of us are pigs."
   Bill: "That was what I said."
   Joe: "What did she say?"
   Bill: "She said that she had seen enough of men to know we are all pigs. She obviously hates all men."
   Joe: "So you think all feminists are like her?"
   Bill: "Sure. They all hate men."

Description of Slippery Slope

The Slippery Slope is a fallacy in which a person asserts that some event must inevitably follow from another without any argument for the inevitability of the event in question. In most cases, 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. This "argument" has the following form:

1.      Event X has occurred (or will or might occur).

2.      Therefore event Y will inevitably happen

Examples of Slippery Slope

1.      "We have to stop the tuition increase! The next thing you know, they'll be charging $40,000 a semester!"

2. "The US shouldn't get involved militarily in other countries. Once the government sends in a few troops, it will then send in thousands to die."
3. "You can never give anyone a break. If you do, they'll walk all over you."
4. "We've got to stop them from banning pornography. Once they start banning one form of literature, they will never stop. Next thing you know, they will be burning all the books!"

Description of Straw Man

The Straw Man fallacy is committed when a person simply ignores a person's actual position and substitutes a distorted, exaggerated or misrepresented version of that position. This sort of "reasoning" has the following pattern:

1.      Person A has position X.

2.      Person B presents position Y (which is a distorted version of X).

3.      Person B attacks position Y.

4.      Therefore X is false/incorrect/flawed.

 Examples of Straw Man

1. "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."
2. Bill and Jill are arguing about cleaning out their closets:
   Jill: "We should clean out the closets. They are getting a bit messy."
   Bill: "Why, we just went through those closets last year. Do we have to clean them out everyday?"
   Jill: "I never said anything about cleaning them out every day. You just want too keep all your junk forever, which is just ridiculous."