What are the formal and informal fallacies you must recognise, and how do you show that an argument commits one?
Fallacies: the formal fallacies (affirming the consequent, denying the antecedent) and the common informal fallacies (ad hominem, straw man, false dilemma, slippery slope, appeal to emotion, begging the question, hasty generalisation and others), with how to identify and explain each.
The fallacies SQA Higher Philosophy expects you to recognise: the formal fallacies of affirming the consequent and denying the antecedent, and the common informal fallacies such as ad hominem, straw man, false dilemma, slippery slope, begging the question and hasty generalisation.
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What this dot point is asking
A fallacy is a mistake in reasoning that makes an argument fail even when it looks persuasive. SQA Higher Philosophy splits them into formal fallacies (flaws in logical form) and informal fallacies (flaws in content, relevance or fairness). You must be able to name the fallacy in a given argument and, crucially, explain why the reasoning is faulty rather than simply attach a label.
Formal fallacies
The two formal fallacies you must recognise are:
- Affirming the consequent: "if P then Q; Q; therefore P". Invalid, because Q could be true for a reason other than P.
- Denying the antecedent: "if P then Q; not P; therefore not Q". Invalid, because Q could still be true through another route.
Both misuse a conditional, treating "if P then Q" as if it meant "P if and only if Q". They are covered in detail alongside the valid forms.
Informal fallacies
The common informal fallacies are:
- Ad hominem. Attacking the arguer instead of the argument. "Ignore his economics, he was bankrupt once."
- Straw man. Misrepresenting an opponent's view to make it easier to attack. "She wants gun control, so she wants to ban all self-defence."
- False dilemma (false dichotomy). Offering only two options when others exist. "Either we cut all spending or the country collapses."
- Slippery slope. Claiming one small step must lead to an extreme outcome, with no support for the chain. "Allow this and soon nothing will be banned."
- Begging the question (circular reasoning). Assuming in a premise the very conclusion to be proved. "The Bible is true because it is the word of God, which we know because the Bible says so."
- Appeal to emotion. Using fear, pity or anger in place of reasons. "Think of the children" with no relevant evidence.
- Appeal to authority (misused). Citing an irrelevant, biased or non-expert "authority". "A famous actor says this diet works."
- Hasty generalisation. Drawing a sweeping conclusion from too small or biased a sample. "Two rude tourists, so everyone from there is rude."
Naming is not enough: explain the flaw
The marks come from explaining why the reasoning fails. For an ad hominem, say that the personal attack is irrelevant to whether the conclusion is true. For a straw man, identify the real position and show how it was distorted. For a false dilemma, name the missing third option. For begging the question, point to the premise that already assumes the conclusion. A bare label such as "that's a straw man" earns little; the explanation of the specific flaw earns the marks.
Examples in context
Consider: "We should not listen to the council's traffic plan, because half of them cannot even park properly." First name the fallacy: this is an ad hominem, attacking the councillors rather than the plan. Then explain the flaw: how well the councillors park is irrelevant to whether their traffic plan is well reasoned or supported by evidence, so the attack does nothing to refute the plan itself. Finally note what a proper response would do, engage with the plan's premises and evidence. That three-step shape, name, explain why it is irrelevant, say what good reasoning would do, is exactly what the question rewards.
Try this
Q1. What is the difference between a formal and an informal fallacy? [2 marks]
- Cue. A formal fallacy is a flaw in the logical form (invalid whatever the content); an informal fallacy is a flaw in the relevance, fairness or clarity of the content.
Q2. Explain why an ad hominem is a fallacy. [2 marks]
- Cue. It attacks the person rather than their argument, and the person's character or conduct is irrelevant to whether their conclusion is actually true.
Exam-style practice questions
Practice questions written in the style of SQA exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
SQA Higher (P1)4 marksIdentify the fallacy committed in the following argument and explain why it is a fallacy.Show worked answer →
Marks are awarded for naming the fallacy and explaining the flaw in the reasoning, not just labelling it. Suppose the argument is: "You cannot trust Dr Khan's claims about climate change; she drives a large car." This is an ad hominem (attacking the person).
Explain the flaw: the argument attacks Dr Khan's character or conduct rather than addressing the evidence or reasoning behind her claims. Whether she drives a large car has no bearing on whether her scientific claims are true, so the attack is irrelevant to the conclusion. A full answer names the fallacy, states what was attacked instead of the argument, and explains why that is irrelevant to the truth of the conclusion.
SQA Higher (P1)4 marksExplain the difference between a formal and an informal fallacy, with an example of each.Show worked answer →
The marks reward a clear distinction plus a correct example of each type. A formal fallacy is a flaw in the logical form of an argument, so the argument is invalid whatever its content; an informal fallacy is a flaw in the content or relevance of the reasoning, not in its form.
Formal example: affirming the consequent ("if P then Q; Q; so P") is invalid because of its shape alone. Informal example: a straw man, where someone misrepresents an opponent's position to attack a weaker version, is a fault of how the argument is conducted, not of its logical form. State that formal fallacies are detected by examining structure (often with a counterexample) while informal fallacies are detected by examining the relevance, clarity or fairness of the content.
Related dot points
- Statements, arguments and standard form: distinguishing arguments from explanations, descriptions and assertions, identifying premises and conclusions using indicator words, and rewriting an argument in standard form.
How to recognise an argument in SQA Higher Philosophy, tell it apart from explanations and descriptions, identify the premises and the conclusion using indicator words, and rewrite the argument in standard form ready for analysis.
- Deductive validity and soundness: the meaning of validity (the conclusion must follow if the premises are true), the meaning of soundness (valid plus all premises actually true), and why a valid argument can have a false conclusion and a true conclusion can come from an invalid argument.
How SQA Higher Philosophy defines deductive validity and soundness: validity as a guarantee that true premises force a true conclusion, soundness as validity plus true premises, and why truth and validity are separate ideas you must not confuse.
- Valid and invalid argument forms: modus ponens, modus tollens, the disjunctive and hypothetical syllogisms; the formal fallacies of affirming the consequent and denying the antecedent; and using the counterexample method to expose an invalid form.
The standard valid argument forms in SQA Higher Philosophy (modus ponens, modus tollens, disjunctive and hypothetical syllogism) and the invalid forms (affirming the consequent, denying the antecedent), with the counterexample method for proving an argument invalid.
- Inductive arguments and reliability: how induction differs from deduction, the main inductive patterns (generalisation from a sample, argument from analogy, causal and predictive inference, appeal to authority), and the criteria that make an inductive argument reliable or weak.
How SQA Higher Philosophy treats inductive reasoning: the difference between induction and deduction, the main inductive forms (generalisation, analogy, causal and predictive inference, appeal to authority), and what makes an inductive argument reliable rather than weak.
- Evaluating arguments: judging the premises for acceptability, judging the premises for relevance to the conclusion, judging whether the premises are sufficient to support the conclusion, and applying the principle of charity when interpreting an argument.
How to evaluate an argument in SQA Higher Philosophy using the criteria of acceptability, relevance and sufficiency, how these criteria connect to validity and soundness, and why the principle of charity matters when interpreting an argument.
- The course assessment: the structure of the externally marked question papers covering Arguments in Action, Knowledge and Doubt and Moral Philosophy, the command words used, and how marks are awarded across short-answer, analysis and extended-response questions.
An overview of how SQA Higher Philosophy is assessed: the externally marked question papers across the three areas of study, the command words (explain, analyse, evaluate), and how marks are awarded across short-answer, analysis and extended-response questions.