Logical Flaws guide
Logical Flaws questions ask you to name the error in an argument's reasoning: correlation treated as causation, necessary confused with sufficient, overgeneralisation, false dilemma, and the like. The flaw is always in the reasoning, not in whether a premise is true.
The method
- Identify how the conclusion is supposed to follow from the premises.
- Name the reasoning error in that move (e.g. correlation ≠ causation, necessary ≠ sufficient).
- Reject options that merely dispute a fact — a flaw is about the reasoning.
- Match the exact flaw family, not just a plausible-sounding one.
How to name the exact reasoning flaw
Strip the argument to its logical move: X happened, then Y happened, therefore X caused Y; if P then Q, Q, therefore P; a few cases had a feature, therefore the whole group does. Naming that abstract move is more reliable than debating the topic.
Then distinguish the flaw from a missing fact. A good answer explains why the conclusion is not licensed even if every premise is accepted. Prefer the most specific description that matches the move actually made.
Final check before you answer
- Accept the premises temporarily and inspect only the inferential step.
- Translate the move into a short abstract form.
- Reject answers that merely say a premise might be false.
Worked method example: sequence does not prove cause
Original teaching example. It is not a live provider question or a premium bank item.
Employee absence fell during the month after the company installed standing desks. The standing desks therefore caused the fall in absence.
Task: What is the flaw?
Answer: The argument treats a sequence and correlation as proof of causation.
Why: The timing is consistent with the conclusion but does not isolate the desks as the cause. Workload, season, staffing or another simultaneous change could explain the fall.
Strongest trap: Saying only that the premise may be inaccurate does not identify the reasoning error. The causal leap remains even if the reported fall is accepted as true.
Common mistakes
- Offering a factual objection instead of a reasoning flaw.
- Naming the right family but the wrong specific flaw.
- Describing the conclusion rather than the flaw in reaching it.
- Assuming a premise is false when the task is about the logic.
Frequently asked questions
Can the flaw be that a premise is untrue?
No. These questions assume the premises and ask what's wrong with the reasoning that connects them to the conclusion.
Practise this now
Preview the question styleOpen the drill
Compare worked critical-reasoning questions
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