Person A makes claim X.
Person B makes an attack on person A.
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
Bill: "I believe that abortion is morally
Dave: "Of course you would say that, you're a
Bill: "What about the arguments I gave to support my
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
Person A makes claim X.
Person B asserts that A's actions or past claims are
inconsistent with the truth of claim X.
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
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
Jill: "Well, I guess smoking can't be that bad. After
all, Bill smokes."
- 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."
- Peter: "Based on the arguments I have presented, it is evident
that it is morally wrong to use animals for food or
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
Bill and Jane are arguing about the morality of
"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
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
Jane: "I don't know. But he's a world famous expert, so I
- 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.
"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
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
- 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.
- Siphwe and Sasha are having a conversation:
"I played the lottery today and I know I am going to win
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
Appeal to Belief is a
fallacy that has this general pattern:
Most people believe that a claim, X, is true.
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
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.
- God must exist. After all, I just saw a poll that says 85% of all
Americans believe in God.
- 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:
Favorable emotions are associated with X.
Therefore Appeal to Emotion, X is true.
An is a fallacy with the
Favorable emotions are associated with X.
Therefore, X is true.
The Appeal to Popularity
has the following form:
Most people approve of X (have favorable emotions
Therefore X is true.
Examples of Appeal to
"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."
- "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
- 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
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.
Premises in which the truth of the conclusion is
claimed or the truth of the conclusion is assumed (either
directly or indirectly).
Claim C (the conclusion) is true.
Examples of Begging the
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."
- "If such actions were not illegal, then they would not be
prohibited by the law."
- "The belief in God is universal. After all, everyone believes
- Interviewer: "Your resume looks impressive but I need another
Bill: "Jill can give me a good reference."
Interviewer: "Good. But how do I know that Jill is
Bill: "Certainly. I can vouch for her."
Examples of Hasty
Generalization (through a biased sample)
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.
- 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
- 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:
A occurs before B.
Examples of Post Hoc
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!
- 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.
- 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.
- 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.
- 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
- 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
A False Dilemma is a
fallacy in which a person uses the following pattern of
Either claim X is true or claim Y is true (when X and Y
could both be false).
Claim Y is false.
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:
Either 1+1=4 or 1+1=12.
It is not the case that 1+1=4.
In cases in which the two
options are, in fact, the only two options, this line of
reasoning is not fallacious. For example:
Bill is dead or he is alive.
Bill is not dead.
Therefore Bill is alive.
Examples of False Dilemma
Senator Jill: "We'll have to cut education funding
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
- Bill: "Jill and I both support having prayer in public
Jill: "Hey, I never said that!"
Bill: "You're not an atheist are you Jill?"
- "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
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:
X has happened.
X departs from what is expected to occur on average or
over the long term.
Therefore, X will come to an end soon.
Examples of Gambler's
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.
- Jane and Bill are talking:
"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
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
- Joe and Sam are at the race track betting on horses.
"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
Description of Hasty
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:
Sample S, which is too small, is taken from population
Conclusion C is drawn about Population P based on S.
Examples of Hasty
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.
- 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
- Bill: "You know, those feminists all hate men."
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
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
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:
Event X has occurred (or will or might occur).
Therefore event Y will inevitably happen
Examples of Slippery Slope
"We have to stop the tuition increase! The next
thing you know, they'll be charging $40,000 a semester!"
- "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."
- "You can never give anyone a break. If you do, they'll walk all
- "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
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:
Person A has position X.
Person B presents position Y (which is a distorted
version of X).
Person B attacks position Y.
Therefore X is false/incorrect/flawed.
Examples of Straw
- "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."
- 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."