Fallacies and Foul Play — Critical Thinking 4 (C1)

CRITICAL THINKING · LESSON 4

Fallacies and Foul Play

C1 (B2–C2) · 90 minutes

Where do you stand?

Task Write a number from 1 to 5 for each statement.

1

strongly agree

2

mostly agree

3

on the fence

4

mostly disagree

5

strongly disagree

1. If an argument contains a fallacy, its conclusion is probably false.

2. A politician's private life is irrelevant to the quality of their arguments.

3. Believing something because an expert says so is lazy thinking.

4. Naming your opponent's fallacy is the best way to win a debate.

READING

Bad arguments that work

An argument can go wrong in two ways. Its premises can be false, or its premises can fail to support its conclusion. A fallacy is a failure of the second kind that is easy to miss: a pattern of reasoning that looks stronger than it is. That appearance is what makes fallacies worth studying. Nobody is fooled by an argument that looks bad.

Logicians distinguish two families. A formal fallacy is an error in the structure of an argument, so it fails whatever the argument is about. "If it rained, the street is wet; the street is wet; so it rained" is invalid in form: a burst pipe would wet the street too. This one is called affirming the consequent. An informal fallacy cannot be seen in the form alone. The problem lies in the content and the context: reasons that are irrelevant, evidence that is

too thin, words that quietly change their meaning. Almost all the fallacies met in advertising, politics and online argument are informal.

The study is old. Aristotle's Sophistical Refutations described thirteen kinds of deceptive argument, six that depend on language and seven that do not. Textbooks have repeated lists of fallacies ever since. In 1970 the Australian philosopher Charles Hamblin attacked this "standard treatment" as "debased, worn-out and dogmatic", and argued that fallacies should be judged in the context of real dialogue between real people. That is the approach of this lesson: the same move can be foul play in one exchange and fair in another.

Bad arguments that work

Bad argument

False premises

Faulty reasoning

Formal fallacy: the form is invalid

Informal fallacy: the content or context fails

A field guide to foul play

Straw man

Ad hominem

Attacking a distorted, weaker version of someone's view instead of the view they actually hold.

Latin for "to the person". Rejecting a claim by attacking the person who makes it, rather than their reasons.

False dilemma

Slippery slope

Presenting two options as the only ones, when there are others.

Claiming that one step will lead, through a chain of further steps, to disaster, without showing that the links will hold.

A field guide to foul play (continued)

Appeal to authority

Tu quoque, or whataboutism

Treating someone's say-so as proof when they are not an expert in the field, or when the experts disagree.

Latin for "you too". Answering a criticism by accusing the critic of the same fault, or another one. The word whataboutism spread after 2008, when The Economist used it for a Soviet-era propaganda habit.

Hasty generalisation

Post hoc

Drawing a general conclusion from too few cases, or from cases that are not representative.

Short for post hoc ergo propter hoc, "after this, therefore because of this". Assuming that because B followed A, A caused B.

READING

When the "fallacy" is fair

Fallacy lists give the impression that each move is always wrong. Most informal fallacies are better seen as ordinary, useful kinds of argument that can be misused. The Canadian philosopher Douglas Walton called them argumentation schemes: reasonable but defeasible patterns, which give a presumption in favour of a conclusion until a good objection defeats it. Each scheme comes with critical questions that test whether this particular use holds up.

Take appeal to authority. Nobody can check everything; we rely on doctors, engineers and reference works every day. Walton's six critical questions for an appeal to expert opinion ask, in effect: Is this person really an expert? In this field? What exactly did they say? Are they trustworthy here, with

nothing to gain? Do other experts agree? Is the claim backed by evidence? A tennis star selling a bank fails these questions; a medicines agency summarising trials can pass them.

Ad hominem is fair when the argument rests on the person. If a witness's testimony is the only evidence, or an "independent" report was paid for by the company it praises, credibility is exactly the question. It is foul when the person's reasons could stand on their own and are ignored.

Slippery slope is fair when each link has a mechanism: a legal precedent, a rule of equal treatment, a known incentive. It is foul when the links are merely imagined, or when nothing explains why nobody could stop halfway down.

Fallacy hunt (items 1–2)

Task For each of items 1–8 (this slide and the next three), write the name of the move, or none. Then write one sentence on why it misleads, or why it is fair. Some items use two moves. Not every item is a fallacy.

SOCIAL POST

1

ADVERT

Norvane Bank

2

@kenji_runs

"Tennis champion Anya Sorensen switched to Norvane and never looked back. 90% of our customers would recommend us."

"Started drinking Kestrel Leaf green tea in January. Not a single cold since. This stuff WORKS."

Small print: survey of 50 customers in their first week.

Fallacy hunt (items 3–4)

SPEECH EXTRACT

3

Senator Ilona Varga, Republic of Marenland

4

RADIO INTERVIEW

Minister Tomás Ferreira

"My opponent wants to cut the defence budget by three per cent. Why does he want to leave our borders open to anyone who wishes us harm?"

Asked about chemical waste in the Sela river, he replies: "Our neighbours in Lindmark love to lecture us about the Sela. Perhaps they should clean up their own coal plants first."

Fallacy hunt (items 5–6)

5

SOCIAL POST

@amara.o

6

SPEECH EXTRACT

Mayor Lucía Ortega

"Interesting that the 'independent' study saying Brisko energy drinks are healthy was paid for by Brisko, and two of its authors work for the company. I'd wait for other studies."

"Either we build the new airport, or our city becomes a ghost town within a decade. There is no third way."

Fallacy hunt (items 7–8)

EMAIL FROM

7

COMMENT UNDER A NEWS ARTICLE

Dimitri K.

8

Professor Wei Lin, head of department

"Why would anyone take housing advice from Farid Haddad? He failed as an actor and he still rents a flat at 45."

"If I extend the deadline for one student without a medical certificate, our rules on equal treatment mean I must offer the same to every student who asks. So I can't make an exception."

Argue badly on purpose

Task

Groups of 3 or 4.

Round 1 uses cards 1–4, round 2 cards 5–8 (groups of 3: cards 1–3, then 5–7).

Each speaker secretly chooses one of the two fallacies on their card and defends the position for 45 seconds without naming the fallacy.

Listeners say "Foul!" when they spot it, name the move and say why it misleads.

Then the speaker reveals.

Finally, one listener gives the best honest reason for the same position, in one sentence.

Argue badly on purpose · The cards

1

Pineapple belongs on pizza

Socks with sandals are perfectly acceptable

False dilemma or appeal to authority.

5

Tu quoque or straw man.

Cats make better companions than dogs

Board games are better than video games

2

Ad hominem or hasty generalisation.

6

Hasty generalisation or slippery slope.

3

Breakfast is the most important meal of the day

7

Films should be watched with subtitles, never dubbed

Post hoc or appeal to authority.

Ad hominem or false dilemma.

4

Everyone should learn to whistle

Slippery slope or straw man.

8

The window seat is the best seat on a plane

Post hoc or tu quoque.

Repair it

Task Choose two of the three arguments (all three if you are quick). Keep the speaker's view, but rewrite the argument honestly, so that a reasonable opponent would have to take it seriously. Then write one piece of evidence that would make your version stronger.

1

TOWN COUNCIL MEETING

2

RADIO PHONE-IN

3

PARENTS' GROUP CHAT

"If we let food trucks into Central Park this summer, next year it'll be a market, then a fairground, and before long there'll be no park left."

"The new cycle lanes are a ridiculous idea dreamed up by people who've never had to drive three kids to school in the rain."

"Either the school bans phones completely, or our children will never read a book again. Anyone who disagrees obviously doesn't care about children."

READING

The fallacy fallacy

Suppose someone argues: "The Earth goes round the Sun, because my horoscope app says so." That is a dreadful appeal to authority. It does not follow that the Earth stands still. Concluding that a claim is false because one argument for it was bad is itself an error, known as the argument from fallacy or the fallacy fallacy. A bad argument shows that this route to the conclusion fails. The conclusion may still be reached by a better one.

There is a second danger. Fallacy names can become weapons.

Crying "Straw man!" or "Ad hominem!" can end a conversation as surely as the fallacy itself, especially when the accused move was fair: a relevant question about a witness's interests, or a slope with a mechanism at every step. Some teachers of argument worry that learning a list of fallacies trains students to see them everywhere. The label is the start of an analysis, not a substitute for one: say what the move is, why it misleads here, and what would have to be true for it to be reasonable.

Calling foul

Task Choose three or four questions. Spend most of your time on the one your group disagrees about.

1. If someone defends your view with a terrible argument, does it weaken your view?

2. Is it ever fair to win a debate by naming your opponent's fallacy and nothing more?

3. Is calling something "whataboutism" sometimes a way of avoiding a fair comparison?

4. Should a politician's private behaviour count when we judge their arguments?

5. Where you live, is it rude to point out a flaw in an elder's or a boss's argument?

6. Does studying fallacies make people better thinkers, or just better at winning arguments?

Private reflection

Task Choose one prompt and write privately. Nobody will read what you write. Sharing afterwards is optional.

Prompt 1

Think of an argument you cared about in which you used one of today's moves yourself. Why did it feel convincing at the time?

Prompt 2 (lighter)

Which of today's moves annoys you most when other people use it? Is there a situation where you would forgive it?

Back to where you stood

Task Look again at your numbers for statements 1 and 4 on the first slide. Would you change either of them now?

1

strongly agree

2

mostly agree

3

on the fence

4

mostly disagree

5

strongly disagree

1. If an argument contains a fallacy, its conclusion is probably false.

4. Naming your opponent's fallacy is the best way to win a debate.

Before Lesson 5

This week, catch one fallacy in the wild, and one fair argument that someone wrongly called a fallacy.

Note where you found each one (an advert, a news programme, a family dinner, a comment thread) and what made it persuasive.

Next lesson: The Biased Brain. Why our own minds take the shortcuts that fallacies exploit.

TEACHER'S REFERENCE · SKIP OR DELETE BEFORE CLASS

Answer key (1)

FALLACY HUNT suggested; items 7 and 8 are there to be argued over

1 Appeal to (irrelevant) authority and hasty generalisation. A tennis champion has no expertise in banking, and a survey of 50 customers in their first week is small and unrepresentative: nobody has had time to be disappointed yet.

2 Post hoc, plus a sample of one. Colds have many causes and vary from year to year; one person's lucky spring proves nothing about the tea.

3 Straw man. A three per cent budget cut is turned into "leaving our borders open". The opponent's actual proposal is never discussed.

4 Tu quoque / whataboutism. Lindmark's coal plants may be a real problem, but they are irrelevant to whether there is chemical waste in the Sela.

5 None. A relevant challenge to credibility: the study's funding and authorship give a real reason for caution. Note that the writer does not claim the study is false, only that she would wait for other studies. Calling this "ad hominem" would itself be the fallacy fallacy.

6 False dilemma. There are other options: a smaller airport, better rail links, other kinds of investment. The "ghost town within a decade" claim is also unsupported.

TEACHER'S REFERENCE · SKIP OR DELETE BEFORE CLASS

Answer key (2)

7 Ad hominem (abusive). His acting career is irrelevant to his housing arguments, which are never addressed. Arguable: whether renting at 45 is relevant at all. Some students will say it gives him first-hand experience of the housing market, which would make it a reason to listen, not to dismiss him.

8 None, or mostly fair. A slippery slope with a mechanism: a stated equal-treatment rule creates a real precedent. Open to challenge, though: the rule could allow exceptions under clear criteria, so the slope is not necessarily as steep as claimed.

REPAIR IT model answers; many good versions are possible

1 "Food trucks in Central Park could bring litter, noise and pressure on the grass. Before we approve them, let's run a one-summer trial with a fixed number of pitches and agreed rules, and review it in the autumn." Evidence: figures on litter and damage from parks in other cities that allowed food trucks.

2 "The new cycle lanes have removed a traffic lane on the main school route, and journeys for parents who drive have become longer. Could the council check the journey times and consider alternatives for families with no other option?" Evidence: journey times on the route before and after the lanes, and how many families depend on driving.

3 "Phones in lessons seem to be distracting our children. I think the school should seriously consider a ban during school hours, and I'd like to hear the case on both sides." Evidence: published research on phone restrictions in schools, or the school's own data on attention, attainment or reading.