The document provides an introduction to common logical fallacies. It defines fallacies as arguments that seem correct but are not valid upon examination. It focuses on three main categories of fallacies: fallacies of relevance, ambiguity, and presumption. Under fallacies of relevance, it discusses the argument from ignorance, appeal to inappropriate authority, appeal to popular opinion, complex question, begging the question, false dilemma, and ad hominem. It also covers fallacies of ambiguity like equivocation and accent. The document aims to help readers identify and avoid using fallacious reasoning.
With a view to employing logic appropriately we should be aware of logical fallacies we might commit. Some are common and unintentional , others are deliberate .Some are tricks to win an argument, others are simply immoral and should be avoided.
With a view to employing logic appropriately we should be aware of logical fallacies we might commit. Some are common and unintentional , others are deliberate .Some are tricks to win an argument, others are simply immoral and should be avoided.
Why are we doing this again1) Generally speaking,.docxphilipnelson29183
Why are we doing this again?1) Generally speaking, humans are not very good at reasoning.2) The purpose of this class is to make you better at reasoning.3) Fallacies are specific examples of bad reasoning, and they are all around us.Thus, learning to recognize fallacies is likely to make you commit them less often, and consequently become a better reasoner.
Hasty generalizationHasty generalization: inappropriately generalizing from too few examples.Anecdotal evidence
Freewrite: Hasty Generalization
Is there reasoning behind prejudice? What is the motivating force of prejudice or racism (as a subcategory of prejudice)? Does a person’s limited experiences with another group lead them to unjustified conclusions about an entire race (in which case it’s a hasty generalization)? Or is it some deep-seated prejudice that goes beyond reason?
Generalization from an exceptional caseGeneralization from an exceptional case: Inappropriately generalizing from cases that are unique, or unusual.Biased sampleSelf-selection fallacy
AccidentAccident: Assuming a general claim applies to a specific case that could be unusual.Example: “In America we have the right to bear arms. So if I want to point a gun at a police officer, I should be able to do so.”
Weak AnalogyWeak analogy: a weak argument based on unimportant or irrelevant similarities between the things being compared.Example: “Going to SWC is like being in prison. After all, both the campus and the prison are buildings constructed by humans.”Example: “Corporations are like people. If people can be tried in a court of law, then so can corporations.”
Untestable ExplanationUntestable explanation: when someone provides an explanation that cannot even be tested in principle.Example: “Charlene is really good at helping people because she gives off such good vibes.”
Slippery SlopeSlippery Slope: the suggestion that something will progress by degrees to an exaggerated or undesirable outcome.
False cause/correlation is not causationFalse cause: assuming that because one event happened after (or around the same time as) another that it was caused by the other.In assuming that one event causes another, the person committing this fallacy can overlook:CoincidenceA common causeRandom variationRegression to the mean
False cause (random variation)“In our tests, we randomly selected men to drive a golf ball as far as they could. We then had them wear our magnetic bracelet and try again. On the second occasion the men hit the ball an average of ten feet further. Our bracelet can lengthen your drive as well.”
False cause (regression to the mean)“The girls were well below their average on Monday, so I made them do 50 sets of pushups. Guess what? Their average was much better on Tuesday. Pushups did the trick.”
Appeal to AuthorityAppeal to authority: giving the opinion of a non-authoritative source to support a claim.Example: “My smart friend says that Obamacare is bad for the country. So he mu.
Chapter 3Evaluating Moral ArgumentsWhat Is Moral Reasoning.docxwalterl4
Chapter 3
Evaluating Moral Arguments
What Is Moral Reasoning?
Moral reasoningis ordinary critical reasoning applied to ethics.
Critical reasoning(also called critical thinking) is the careful, systematic evaluation of statementsand arguments.
Statements
A statement(or claim) is the assertion that something is either true or false. The following are examples of statements:“Murder is wrong.”“1 + 1 = 2”“Shakespeare wrote The Tempest.”
Statements and Arguments –1
When at least one statement attempts to provide reasons for believing another statement, we have an argument—a group of statements, one of which is supposed to be supported by the rest.
Statements and Arguments –2
The supporting statements are called premises.
The statement that is being supported by the others is the conclusion.
Identifying ArgumentsAn argumentis intended to prove something.All arguments share a pattern: at least one premise is required to support a conclusion.A cluster of unsupported claims is not an argument.The most reliable way to identify arguments is to look for the conclusion first.Look for indicator words:terms that often appear in arguments and signal that a premise or conclusion may be nearby.
Some words indicating a conclusion:
Therefore, consequently, hence, it follows that, thus, so, it must be thatSome words indicating a premise:
Because, since, for, given that, due to the fact that, for the reason that, the reason being, assuming that, as indicated by
Two Forms of Argument
A deductive argumentis supposed to give logically conclusivesupport to its conclusion.
An inductive argumentis supposed to offer probablesupport to its conclusion.
Common Deductive Argument FormsValid forms:Denying the antecedentAffirming the consequent Invalid forms:Affirming the antecedent(modus ponens)Denying the consequent(modus tollens)The hypothetical syllogism
Deductive Arguments
A deductive argument isvalidif the premises support the conclusion. That is, the conclusion follows necessarily from the premises. If the premises are true, then the conclusion must be true.
A deductive argument is invalidif the premises do not support the conclusion. That is, the conclusion does not follow necessarily from the premises. If the premises are true, then the conclusion may or may not be true.
A deductive argument is sound if it is valid and all its premises are true.
A deductive argument is unsound if it is invalid and/or any of its premises are false.
Inductive Arguments
An inductive argument is strongif it gives probable support to its conclusion. That is, if its premises are true, its conclusion is also likely to be true.
An inductive argument is weak if it does not give probable support to its conclusion. That is, if its premises are true, its conclusion is not more probable than not to be true.
An inductive argument is cogentif it is strong and all of its premises are true.
An inductive argument is not cogent if it is weakand/or any of.
03. intro to argument, informal fallaciesJustin Morris
Thank You for Arguing (TYFA) Selected pages:
Team 1: Ch. 1 (3-15)
Team 2: Ch. 2 (15-26)
Team 3: Ch. 3 (27-37)
Team 4: Ch. 14 (137-154)
Team 5: Ch. 15 (155-170)
Team 6: Ch. 16 (171-180)
Similar to FALLACIES Critical Thinking First PPT July 2016 (20)
These slides are for the first week class where we go through the course outline, and introduce the idea of Critical Thinking within University Education.
Critical Thinking course at Strathmore University is a core Unit and hence a requirement for graduation. This slides were used for the first class hence a lot of focus is on course content and and a little part of topic one.
This is a group work that was done by students studying Ethics at Strathmore University, School of Accountancy. Visit the class blog- http://ethics-talk.bogspot.com. for more details.
This slides are meant ti introduce a course on moral philosophy. All photos in it came from the net. Sources are not included though they are mainly from Google images.
3. Fallacies
ILO
1. Define various types of fallacies
2. Identify fallacies in arguments
3. Show weaknesses of a fallacious
argument and correct the identified
fallacies.
4.
5. What are fallacies
• Fallacy is a type of argument that may
seem to be correct, but that proves, on
examination, not to be so.
• Most fallacies are normally
psychologically persuasive- although
some fallacies can hardly persuade or
deceive any normal person
7. Copi and Cohen’s text book
• We shall focus on
– Fallacies of relevance
– Fallacies of ambiguity
– Fallacies presumption
8. Fallacies of Relevance
• Fallacies of Relevance are committed
when an argument relies on premises that
are not relevant to its conclusion and that
therefore cannot possibly establish its
truth.
• Unwary persons fall into fallacies of
relevance due to their persuasiveness
and their seeming correctness- premises
that are psychologically relevant
9. The argument from
ignorance
argument ad ignorantiam
• In an argument from ignorance, it is
argued that a proposition is true simply on
the basis that it has not been proven
false, that it is false because it has not
been proven true
For example: “You can’t prove that there
aren’t Martians living in caves under the
surface of Mars, so it is reasonable for me
to believe there are.”
10. The appeal to inappropriate
authority: argument ad
verecudiam
• When the appeal is made to parties
having no legitimate claim to authority
in the matter at hand.
• Buy Samsung because Drogba
recommends it
• Also common in moral debates
11. Appeal to Popular
Opinion
• This type of appeal is when someone
claims that an idea or belief is true
simply because it is what most people
believe.
For example: “Lots of people bought this
album, so it must be good.”
12. Complex Question
• Asking a question in such a way as to
presuppose the truth of some
conclusion buried in the question
• For example: “If aliens didn’t steal my
newspaper, who did?” (assume that the
newspaper was actually stolen).
13. Begging the question: petitio
principii
• Assuming the truth of what one seeks
to prove.
• All of us cannot be famous, because all of us
cannot be well known
14. False
Dilemma/Dichotomy
• Sometimes referred to as Bifurcation,
this type of fallacy occurs when
someone presents their argument in
such a way that there are only two
possible options.
• For example: “If you don’t vote for this
candidate, you must be a Communist.”
15. Argument ad hominem
• A fallacious attack in which the thrust is
directed, not at a conclusion, but at the
person who asserts or defends it.
– Argument ad hominem abusive: attacking
the intelligence, integrity, reasonableness
of others etc
– Argument ad hominem circumstantial
16. Accident and converse
accident
• When we apply a generalization to
individual cases that it does not
properly govern.
• Or when we by design or carelessly
apply a principle that is true of a
particular case to the great run of case.
• i.e. Are there Jews in your house? From a Gestapo. No!
17. False cause
• Treating something as the cause of
something else when in reality it is not
the cause.
Post hoc ergo propter hoc
After a thing therefore because of a thing
18. Appeal to Emotions
• Replaces the laborious task of
presenting evidence and rational
argument with expressive language
and other devices calculated to excite
enthusiasm, excitement, anger, or
hate.
• Politics, adverts
19. The appeal to pity; argument
ad misericordiam
• Going for the mercy
The appeal to force; argument ad
baculum
• To the stick- abandonment of reason
20. Fallacies of Ambiguity
• Equivocation- when we confuse
several meanings of a word or phrase-
accidentally or deliberately- we are
using the word equivocally
21. Amphiboly
• A statement is rendered amphibolous
when the loose or awkward
combination of its words renders its
meaning indeterminate.
• Passing someone
on the road
a load
22. Accent
• When a premises relies for its apparent
meaning on one possible emphasis,
but a conclusion drawn from it relies on
the meaning of the same word
accented differently.
i.e. We should not speak ill of our friends
23. Hasty Generalization
• Definition: Making assumptions about a whole
group or range of cases based on a sample that is
inadequate (usually because it is atypical or just too
small).
– Stereotypes about people are a common example of the
principle underlying hasty generalization.
• Example: "My roommate said her philosophy class
was hard, and the one I'm in is hard, too. All
philosophy classes must be hard!"
– Two people's experiences are, in this case, not enough on
which to base a conclusion.
24. Missing the Point
• Definition: The premises of an argument do support
a particular conclusion--but not the conclusion that
the arguer actually draws.
• Example: "The seriousness of a punishment should
match the seriousness of the crime. Right now, the
punishment for drunk driving may simply be a fine.
But drunk driving is a very serious crime that can kill
innocent people. So the death penalty should be the
punishment for drunk driving."
– The argument actually supports several conclusions-- "The
punishment for drunk driving should be very serious," in
particular--but it doesn't support the claim that the death
penalty, specifically, is warranted.
25. Slippery Slope
• Definition: The arguer claims that a sort of chain reaction, usually
ending in some dire consequence, will take place, but there's really
not enough evidence for that assumption.
– The arguer asserts that if we take even one step onto the "slippery
slope," we will end up sliding all the way to the bottom; he or she
assumes we can't stop halfway down the hill.
• Example: "Animal experimentation reduces our respect for life. If we
don't respect life, we are likely to be more and more tolerant of
violent acts like war and murder. Soon our society will become a
battlefield in which everyone constantly fears for their lives. It will be
the end of civilization. To prevent this terrible consequence, we
should make animal experimentation illegal right now."
– Since animal experimentation has been legal for some time and
civilization has not yet ended, it seems particularly clear that this chain
of events won't necessarily take place.
Also known as
“the Camel’s Nose
26. Weak Analogy
• Definition: Many arguments rely on an analogy between two or more
objects, ideas, or situations. If the two things that are being compared aren't
really alike in the relevant respects, the analogy is a weak one, and the
argument that relies on it commits the fallacy of weak analogy.
• Example: "Guns are like hammers--they're both tools with metal parts that
could be used to kill someone. And yet it would be ridiculous to restrict the
purchase of hammers--so restrictions on purchasing guns are equally
ridiculous."
– While guns and hammers do share certain features, these features (having metal
parts, being tools, and being potentially useful for violence) are not the ones at
stake in deciding whether to restrict guns. Rather, we restrict guns because they
can easily be used to kill large numbers of people at a distance. This is a feature
hammers do not share--it'd be hard to kill a crowd with a hammer. Thus, the
analogy is weak, and so is the argument based on it.
• If you think about it, you can make an analogy of some kind between almost
any two things in the world: "My paper is like a mud puddle because they
both get bigger when it rains (I work more when I'm stuck inside) and they're
both kind of murky." So the mere fact that you draw an analogy between two
things doesn't prove much, by itself.
27. Appeal to Ignorance
• Definition: In the appeal to ignorance, the arguer basically says,
"Look, there's no conclusive evidence on the issue at hand.
Therefore, you should accept my conclusion on this issue."
• Example: "People have been trying for centuries to prove that God
exists. But no one has yet been able to prove it. Therefore, God does
not exist."
Here's an opposing argument that commits the same fallacy:
• "People have been trying for years to prove that God does not exist.
But no one has yet been able to prove it. Therefore, God exists."
– In each case, the arguer tries to use the lack of evidence as support for a
positive claim about the truth of a conclusion. There is one situation in
which doing this is not fallacious: If qualified researchers have used well-
thought-out methods to search for something for a long time, they haven't
found it, and it's the kind of thing people ought to be able to find, then the
fact that they haven't found it constitutes some evidence that it doesn't
exist.
28. Straw Man
• Definition: One way of making our own arguments stronger is to
anticipate and respond in advance to the arguments that an
opponent might make. The arguer sets up a wimpy version of the
opponent’s position and tries to score point by knocking it down.
• Example: "Feminists want to ban all pornography and punish
everyone who reads it! But such harsh measures are surely
inappropriate, so the feminists are wrong: porn and its readers
should be left in peace."
– The feminist argument is made weak by being overstated--in fact, most
feminists do not propose an outright "ban" on porn or any punishment
for those who merely read it; often, they propose some restrictions on
things like child porn, or propose to allow people who are hurt by porn to
sue publishers and producers, not readers, for damages.
29. Red Herring
• Definition: Partway through an argument, the arguer goes off on a
tangent, raising a side issue that distracts the audience from what's
really at stake. Often, the arguer never returns to the original issue.
• Example: "Grading this exam on a curve would be the most fair thing
to do. After all, classes go more smoothly when the students and the
professor are getting along well." Let's try our premise-conclusion
outlining to see what's wrong with this argument:
– Premise: Classes go more smoothly when the students and the professor
are getting along well.
– Conclusion: Grading this exam on a curve would be the most fair thing to
do.
• When we lay it out this way, it's pretty obvious that the arguer went off
on a tangent--the fact that something helps people get along doesn't
necessarily make it more fair; fairness and justice sometimes require
us to do things that cause conflict. But the audience may feel like the
issue of teachers and students agreeing is important and be
distracted from the fact that the arguer has not given any evidence as
to why a curve would be fair.
30. False Dichotomy
• Definition: In false dichotomy, the arguer sets up
the situation so it looks like there are only two
choices. The arguer then eliminates one of the
choices, so it seems that we are left with only one
option: the one the arguer wanted us to pick in the
first place.
• Example: "Caldwell Hall is in bad shape. Either we
tear it down and put up a new building, or we
continue to risk students' safety. Obviously we
shouldn't risk anyone's safety, so we must tear the
building down."
– The argument neglects to mention the possibility that we
might repair the building or find some way to protect
students from the risks in question--for example, if only a
few rooms are in bad shape, perhaps we shouldn't hold
classes in those rooms.
31. Begging the Question
• Definition: A complicated fallacy, an argument that begs the question asks the reader
to simply accept the conclusion without providing real evidence
– the argument either relies on a premise that says the same thing as the conclusion (which
you might hear referred to as "being circular" or "circular reasoning"), or simply ignores an
important (but questionable) assumption that the argument rests on.
– Sometimes people use the phrase "beg the question" as a sort of general criticism of
arguments, to mean that an arguer hasn't given very good reasons for a conclusion, but
that's not the meaning we're going to discuss here.
• Examples: "Active euthanasia is morally acceptable. It is a decent, ethical thing to
help another human being escape suffering through death." Let's lay this out in
premise-conclusion form:
– Premise: It is a decent, ethical thing to help another human being escape suffering through
death.
– Conclusion: Active euthanasia is morally acceptable.
• If we "translate" the premise, we'll see that the arguer has really just said the same
thing twice: "decent, ethical" means pretty much the same thing as "morally
acceptable," and "help another human being escape suffering through death" means
"active euthanasia." So the premise basically says, "active euthanasia is morally
acceptable," just like the conclusion does! The arguer hasn't yet given us any real
reasons why euthanasia is acceptable; instead, she has left us asking "well, really,
why do you think active euthanasia is acceptable?" Her argument "begs" (that is,
evades) the real question (think of "beg off").
32. Equivocation
• Definition: Equivocation is sliding between two or
more different meanings of a single word or phrase
that is important to the argument.
• Example: "Giving money to charity is the right thing
to do. So charities have a right to our money."
– The equivocation here is on the word "right": "right" can
mean both something that is correct or good (as in "I got
the right answers on the test") and something to which
someone has a claim (as in "everyone has a right to life").
– Sometimes an arguer will deliberately, sneakily equivocate,
often on words like "freedom," "justice," "rights," and so
forth; other times, the equivocation is a mistake or
misunderstanding. Either way, it's important that you use
the main terms of your argument consistently.
33.
34. Can you name this
Fallacy?
It is ridiculous to have spent thousands
of dollars to rescue those two whales
trapped in the Arctic ice. Why look at all
the people trapped in jobs they don’t
like.
RED HERRING
35. Can you name this
Fallacy?
Plagiarism is deceitful because it is
dishonest.
BEGGING THE QUESTION
36. Can you name this
Fallacy?
Water fluoridation affects the brain.
Citywide, student’s test scores began
to drop five months after fluoridation
began.
POST HOC (false cause)
37. Can you name this
Fallacy?
I know three redheads who have terrible
tempers, and since Annabel has red
hair, I’ll bet she has a terrible temper
too.
HASTY GENERALIZATION
38. Can you name this
Fallacy?
Supreme Court Justice Byron White was
an All-American football player while in
college, so how can you say that
athletes are dumb?
HASTY GENERALIZATION
39. Can you name this
Fallacy?
Why should we put people on trial when
we know they are guilty?
BEGGING THE QUESTION
40. Can you name this
Fallacy?
You support capital punishment just
because you want an “eye for an eye,”
but I have several good reasons to
believe that capital punishment is
fundamentally wrong…
STRAW MAN
41. Can you name this
Fallacy?
The meteorologist predicted the wrong
amount of rain for May. Obviously the
meteorologist is unreliable.
HASTY GENERALIZATION
42. Can you name this
Fallacy?
You know Jane Fonda’s exercise video’s
must be worth the money. Look at the
great shape she’s in.
POST HOC (false cause)
43. Can you name this
Fallacy?
We have to stop the tuition increase! The
next thing you know, they'll be charging
$40,000 a semester!
SLIPPERY SLOPE
44. Can you name this
Fallacy?
The book Investing for Dummies really
helped me understand my finances
better. The book Chess for Dummies
was written by the same author, was
published by the same press, and
costs about the same amount, so it
would probably help me understand my
finances as well.
WEAK ANALOGY
45. Can you name this
Fallacy?
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.
FALSE DICHOTOMY (Dilemma)
46. Can you name this
Fallacy?
I'm positive that my work will meet your
requirements. I really need the job
since my grandmother is sick.
APPEAL TO PITY
47. Can you name this
Fallacy?
Crimes of theft and robbery have been
increasing at an alarming rate lately.
The conclusion is obvious, we must
reinstate the death penalty
immediately.
MISSING THE POINT
48. Can you name this
Fallacy?
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.
APPEAL TO AUTHORITY
49. Can you name this
Fallacy?
Buy Samsung because Drogba
recommends it.
The appeal to inappropriate authority:
argument ad verecudiam
50. Can you name this
Fallacy?
“Lots of people bought this album, so it
must be good.”
Appeal to Popular Opinion
51. Can you name this
Fallacy?
“If aliens didn’t steal my newspaper, who
did?”
Complex Question
52. Can you name this
Fallacy?
All of us cannot be famous, because all
of us cannot be well known
Begging the question: petitio principii
53. Can you name this
Fallacy?
“If you don’t vote for this candidate, you
must be a Communist.”
False Dilemma/Dichotomy
54. Can you name this
Fallacy?
“All Dubliners are from Ireland. Ronan is
not a Dubliner, therefore, he is not Irish.”
• Non Sequitur