A selection of examples of different types of logical fallacies.

1. Fallacies
bad arguments that might look good
George W. Matthews
Pennsylvania College of Technology
Fall 2015

2. types of logical fallacies
1. fallacies of relevance
These have in common the use of irrelevant
information to try to persuade us into believing
the conclusion.
2. fallacies of ambiguity
These rest on the multiple meanings that often
are attached to individual words and concepts.
3. fallacies of presumption
These make additional unstated assumptions not
warranted by the context.

3. fallacies of relevance
appeal to authority
Experts say that drinking a glass of milk a
day is the best way to lose weight. Thus it
is a good idea to drink a glass of milk a
day.

4. fallacies of relevance
appeal to authority
Experts say that drinking a glass of milk a
day is the best way to lose weight. Thus it
is a good idea to drink a glass of milk a
day.
It is always a bad idea to trust someone just because
they have the status of an expert. The experts might
be right, but then don’t we need to see their evidence?

5. fallacies of relevance
ad hominem
Ms. X says that animals deserve rights.
But we don’t have to listen to her since
she is wearing leather shoes.

6. fallacies of relevance
ad hominem
Ms. X says that animals deserve rights.
But we don’t have to listen to her since
she is wearing leather shoes.
Ad hominem means “against the person.” This is a
fallacy because it ignores what is being said and
focuses on who is saying it.

7. fallacies of relevance
popular appeal
The death penalty is supported by a
majority of people. Therefore it is a
justified punishment.

8. fallacies of relevance
popular appeal
The death penalty is supported by a
majority of people. Therefore it is a
justified punishment.
Once again there is an irrelevant appeal made here to
something that has no bearing on the truth of the
conclusion. Just because many people believe
something does not by itself mean that they are correct.

9. fallacies of relevance
appeal to force
Either my work is good enough for me to
pass this course or you are a dead man.

10. fallacies of relevance
appeal to force
Either my work is good enough for me to
pass this course or you are a dead man.
Yes, threats may get people to do what you want them
to do, but they fail to provide reasons to believe what
you are saying.

11. fallacies of relevance
appeal to consequences
If evolution is true, then we are all related
to apes. But this is something I really don’t
like to admit. So evolution must be false.

12. fallacies of relevance
appeal to consequences
If evolution is true, then we are all related
to apes. But this is something I really don’t
like to admit. So evolution must be false.
Remember that the merely uncomfortable
consequences of a theory do not make that theory
false. Truth or falsity depends on evidence that directly
bears on the case.

13. fallacies of relevance
naturalistic fallacy
Women alone are capable of getting
pregnant and having babies. Therefore us
men should not be responsible for changing
diapers.

14. fallacies of relevance
naturalistic fallacy
Women alone are capable of getting
pregnant and having babies. Therefore us
men should not be responsible for changing
diapers.
The premise is about the facts of human nature and is
clearly true. But the conclusion is about something
very different – the question of social roles which are
up to us to create as we see fit. Hence appealing to
nature here is irrelevant.

15. fallacies of relevance
red herring
That guy claims that animals have rights.
Well he should consider doing something
more to protect humans. After all, there
are plenty of people who are in need of
protection from tyranny and abuse.

16. fallacies of relevance
red herring
That guy claims that animals have rights.
Well he should consider doing something
more to protect humans. After all, there
are plenty of people who are in need of
protection from tyranny and abuse.
This fallacy gets its name from a tactic used to throw
off bloodhounds – wipe a (reddish colored) piece of
smoked fish across the trail and toss it into the bushes
nearby. Changing the subject is not arguing fairly.

17. fallacies of relevance
weak analogy
Asking me to pay taxes is like asking me to
let you steal money directly from by
banking account, and that’s just not right!

18. fallacies of relevance
weak analogy
Asking me to pay taxes is like asking me to
let you steal money directly from by
banking account, and that’s just not right!
We should be careful with our use of analogies,
especially when one of the terms has very strong
emotional content. A weak analogy is one where
relevant differences between two analogous things are
ignored.

19. fallacies of ambiguity
equivocation
If you can think whatever you want, you
are really free. People in jail can think
whatever they want. So they should stop
whining about wanting to be free.

20. fallacies of ambiguity
equivocation
If you can think whatever you want, you
are really free. People in jail can think
whatever they want. So they should stop
whining about wanting to be free.
Note the change in meanings of the word “free” here.
To equivocate is to confuse multiple different meanings
of a word with each other.

21. fallacies of ambiguity
straw person
By asking for us to withdraw our troops
from that country those hippies are saying
we shouldn’t ever defend ourselves from
attack!

22. fallacies of ambiguity
straw person
By asking for us to withdraw our troops
from that country those hippies are saying
we shouldn’t ever defend ourselves from
attack!
We should always be careful to avoid creating a
caricature of any position we oppose. Such a view
might be easy to knock down but if we are after the
truth, misrepresenting other viewpoints does not get us
any closer to it.

23. fallacies of presumption
mere assertion
There are simply no grounds for believing
that global warming is caused by humans.

24. fallacies of presumption
mere assertion
There are simply no grounds for believing
that global warming is caused by humans.
Is there even a reason given here?

25. fallacies of presumption
begging the question
You should be a Christian. After all, the
Bible says that you will go to Hell if you
are not a Christian.

26. fallacies of presumption
begging the question
You should be a Christian. After all, the
Bible says that you will go to Hell if you
are not a Christian.
We beg the question whenever we assume in the
premises of our argument the very question we are
claiming to prove. This is also known as “preaching to
those already converted.”

27. fallacies of presumption
appeal to ignorance
Nobody has ever proven that the death
penalty deters crime. It is most likely not
even possible to prove this. Thus it does
not deter crime.

28. fallacies of presumption
appeal to ignorance
Nobody has ever proven that the death
penalty deters crime. It is most likely not
even possible to prove this. Thus it does
not deter crime.
To quote from Dick Cheney – “lack of evidence is not
evidence of a lack.” Just because we do not know
something does not mean we are entitled to conclude
that it is false.

29. fallacies of presumption
false dilemma
Either you agree with me that Donald
Trump would be a great president or you
are a communist. Since you do not agree
with me, you are clearly a communist.

30. fallacies of presumption
false dilemma
Either you agree with me that Donald
Trump would be a great president or you
are a communist. Since you do not agree
with me, you are clearly a communist.
In spite of its popularity in political campaigns this
argument strategy clearly doesn’t work – how many
other possibilities are just not mentioned? Another
name for this fallacy is the “black or white fallacy.”

31. fallacies of presumption
hasty generalization
Most people are against raises taxes to
fund public transportation. After all 95
percent of my friends are.

32. fallacies of presumption
hasty generalization
Most people are against raises taxes to
fund public transportation. After all 95
percent of my friends are.
It is possible to legitimately generalize from a sampling
of data from a larger set, but only if you take steps to
avoid a biased sample.

33. fallacies of presumption
slippery slope
If we legalize physician assisted suicide or
euthanasia, anyone over 60 had better
watch their backs.

34. fallacies of presumption
slippery slope
If we legalize physician assisted suicide or
euthanasia, anyone over 60 had better
watch their backs.
This fallacy involves arguing against something
relatively uncontroversial by highlighting a possible, but
highly improbable, and highly undesirable consequence.
What is the mechanism that would propel us down the
slippery slope? Often it is not spelled out.

35. fallacies of presumption
false cause
Two days ago I had a bad cold. Then I
drank a bottle of whiskey. Thus whiskey
must cure colds.

36. fallacies of presumption
false cause
Two days ago I had a bad cold. Then I
drank a bottle of whiskey. Thus whiskey
must cure colds.
This fallacy confuses correlation with causation and is
especially popular among peddlers of remedies for a
disease that has no cure – the common cold. It is also
known by the fancy Latin name: post hoc, ergo propter
hoc, which translates as “after which, therefore
because of which.”

37. fallacies of presumption
circular reasoning
He definitely did it, since he has a guilty
look on his face. And it is clear that it is a
guilty look, since he is the one who did it.

38. fallacies of presumption
circular reasoning
He definitely did it, since he has a guilty
look on his face. And it is clear that it is a
guilty look, since he is the one who did it.
Which is the premise here and which is the conclusion?
Both and neither since the first leads to the second
which leads to the first. Round and round we go.

39. For more types of fallacies and many more
examples, check out the links below. Or
pick up any newspaper.