Argument

Straw men, slippery slopes and other tricks that sound like arguments

Why do bad arguments sound so convincing? A walk through the most common fallacies – straw man, ad hominem, false dilemma, slippery slope and the rest – with everyday examples, and with the cases where they are not fallacies at all.

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What this covers

  1. What a fallacy actually is, and what it is not
  2. The straw man – answering something the other person did not say
  3. Ad hominem, and when it is actually relevant
  4. The false dilemma
  5. The slippery slope, and when it is not a fallacy
  6. The appeal to authority, and why it is usually fine
  7. Circular arguments and shifting the burden of proof

What this covers (cont.)

  1. Whataboutism
  2. No true Scotsman
  3. Appeals to nature and to tradition
  4. Hasty generalisation, and correlation that is not cause
  5. The Gish gallop and motte-and-bailey
  6. The fallacy fallacy

What a fallacy actually is

A fallacy is an error in the argument, not in the conclusion. It is a piece of reasoning where the premises do not carry the claim, even though it may sound entirely right.

The straw man

The most common trick of all. You build a weaker version of what the other person said, knock it down, and act as though you have won.

The straw man, side by side

What was said

Lower the limit in residential streets

  • Applies to one particular place
  • Says nothing about other roads
  • No figure attached

What was answered

Walking pace everywhere

  • Applies to every road
  • An extreme nobody proposed
  • Easy to dismiss
The straw man moves the claim somewhere it never was, and knocks it down there. Note that the right-hand version is easier to disagree with – that is the whole purpose.

Ad hominem – and when it is not a fallacy

Attacking the person instead of the argument:

When the person is relevant, and when they are not

Claim about the personDoes it bear on the matter?Verdict
“He is a bad father”No. Fatherhood says nothing about climate science.Fallacy
“The report was paid for by the industry it assesses”Yes. A conflict of interest affects how much weight an assessment deserves.Valid point
“She has never worked in the field”It depends. Relevant for experience-based knowledge, less so for a calculation.To be judged
The same move, three different outcomes. The test is never “are they attacking the person?”, but “does the trait have anything to do with the claim?”.

The appeal to authority – which is usually fine

This is the most misused label on the list. People shout “appeal to authority” whenever anyone cites an expert, and that is wrong.

Three questions before trusting an authority

  1. Is the person an expert on this exact thing?Not on something nearby – on this particular claim.
  2. Is the authority real?What sits behind the title? Training, publications, practice?
  3. Does the field agree?One researcher is not “the research”. Is this the breadth, or one extreme?
  4. Three yeses is good reason to trust itOne no does not make the claim false – only that the authority does not settle it.
Pointing to experts is ordinary thinking. The fallacy only arises when one of the first three answers is no and the authority is used as an argument anyway.

The false dilemma

Two options presented as though they were the only ones.

The slippery slope – which often is not a fallacy

> — Allow this, and we will end up allowing anything.

Two slippery slopes, the same shape

The links hold

  1. AThe step is argued for
  2. BThe step is argued for
  3. CValid argument

The links do not hold

  1. AThe step is argued for
  2. ?No argument given
  3. ZFallacy
The shape is identical. The difference lies in whether each link actually follows from the one before, or whether it is merely asserted that it does.

The circular argument

The conclusion is already contained in the premise.

Shifting the burden of proof

> — Can you prove it doesn't exist?

Whataboutism

Answering criticism by pointing at something else.

No true Scotsman

A counter-example is defined away instead of being taken seriously.

Appeals to nature and to tradition

> — It is natural, therefore it is good. > — We have always done it this way.

Hasty generalisation, and correlation that is not cause

Two that belong together.

The Gish gallop and motte-and-bailey

Two tricks you notice most in online debate.

The fallacy fallacy

The most important one, and the one that makes this whole list dangerous to learn.

A bad argument for something true is still a bad argument – and the claim is still true.

Example: “The Earth is round because my grandmother said so.” The argument does not hold. The Earth is round anyway.

How to actually respond

Four moves that work better than quoting Latin:

Key points

  • A fallacy is an error in the argument, not in the conclusion.
  • The straw man is the most common trick, and the easiest to commit without meaning any harm.
  • Ad hominem and the appeal to authority are only fallacies when the trait is irrelevant to the question.
  • A slippery slope with a real causal chain is a perfectly valid argument.

Key points (cont.)

  • Whoever makes the claim carries the burden of proof. You do not have to prove a negative.
  • Someone arguing badly does not mean they are wrong. That is a fallacy of its own.

Questions this answers

  • What is a logical fallacy?
  • What is a straw man?
  • Is ad hominem always a fallacy?
  • When is it acceptable to cite an authority?
  • What is a false dilemma?
  • Is the slippery slope always wrong?

Questions this answers (cont.)

  • What is whataboutism?
  • Who carries the burden of proof in a disagreement?
  • Does a bad argument make the conclusion false?
  • How do you answer a rhetorical trick without becoming insufferable?

Sources

  • Douglas Walton – Informal Logic (2nd ed. 2008)

Spørretimen

Read the whole thing at

www.sporretimen.no/en/episodes/logiske-feilslutninger/