Spotting the Mistake

In these questions someone reasons out loud and lands too hard on a conclusion — and you pick the sentence that names their mistake. Example: Ali finds a green umbrella with a wooden handle and says 'it must be Mei's!' The flaw: there might be MORE THAN ONE green umbrella with a wooden handle — matching a description doesn't make it THE one. The mistake is always a JUMP: a gap between what the facts say and what the speaker concluded. Best habit: spot the jump in your own words BEFORE reading the options, then find the option that says it. About six of the thirty questions on the real paper are this type, so the eight families in this lesson are worth knowing cold.

Flaw family 1: MORE THAN ONE MATCH. A description — green umbrella with a wooden handle, big grey bird, house with a red door — usually fits several things, so 'it matches, therefore it's THE one' is a jump. To convict this flaw, ask: could something ELSE fit the same description? If yes, the speaker needed to rule the others out and didn't. This is the frogmouth-egg trap too: 'white and a decent size, so it must be a frogmouth's' fails because the box never says only frogmouths lay white eggs. The fix words in correct options: 'there might be more than one…', 'another … could also…'.

Flaw family 2: MINIMUM ≠ GUARANTEE. Example: Coach Lin says at least three practice laps a week are needed to have ANY CHANCE of being picked for the relay. Devi runs five a week and concludes she's SURE to be picked. The jump: a minimum requirement is an entry ticket, not a prize — meeting it puts you in the race; it doesn't win the race. Same with 'at least ten lessons before the music exam': doing twelve doesn't make passing certain. Spot the pattern: requirement met → 'so I'm sure to succeed'. The correct option says: meeting the minimum doesn't guarantee success.

Flaw family 3: THE FORGOTTEN POSSIBILITY. Example: Mr Osei knows 12 children ordered the school photo, received 9 envelopes, and concludes the other 3 MUST be paying online. He's forgotten a third option: a child might not have paid at all yet — envelope left at home, forgotten, or coming tomorrow. 'Must' claims collapse the moment one uncounted possibility exists. Your move: list ALL the ways the facts could be true. If the speaker's conclusion is just one of several open doors, the mistake is 'they might not have paid yet'.

Flaw family 4: MY EXPERIENCE SAYS OTHERWISE. Example: a survey says nearly half of Australian children play a team sport, and Ravi replies that it can't be true because nobody in his street does. The jump is treating a handful of people he knows as if they stood for millions. A small group can easily be untypical — Ravi's street might be full of very young children, or of families who prefer music — while the statistic stays true. The correct option is the one that says his group might not be typical. Options that merely doubt the survey, or talk about other activities, leave his actual jump untouched.

Flaw family 5: SAME TIME, SO IT CAUSED IT. Example: a scientist notes the school pond has fewer frogs than last year and that a car park was built beside it this year, and concludes the car park must be driving the frogs away. Two things changing together does not show that one caused the other. Something else may have changed as well — a dry spring, a new heron, a chemical in the water — and any one of those fits the facts just as well. The winning option names a different possible cause: 'the spring may have been much drier than usual'. Options about other ponds, or about car parks being useful, are true-sounding but do not offer a rival cause, so they don't touch the jump.

Flaw family 6: THIS CAUSE, SO NOT THAT ONE. Example: Ms Ito's lettuces failed; either the month was too dry or slugs ate the seedlings. She checks the rain records, finds the month was indeed dry, and concludes the slugs are innocent. But proving one reason true does not make the other false — the dry weather could have weakened the plants and the slugs could have eaten what was left. The winning option says both may have played a part. Watch for the word 'shouldn't blame' or 'so it can't have been': that is the speaker switching off a cause that was never ruled out.

Flaw family 7: THE COMPARISON LEFT SOMETHING OUT. Example: Noor is queuing at a printer that takes 15 minutes to print her booklet; another printer takes 10 and is a short walk away, so she decides to switch and get her booklet sooner. She has counted printing time and walking time but not queuing time — and there may be a longer queue at the other printer. A comparison is fair only when it counts the same things on both sides. The chess version: Ola won 9 of 10 games and Sam 4 of 12, so Ola must be the better player — but the comparison left out who they played; Sam may have faced far stronger opponents. The winning option names the thing left out, not a matter of taste like cost or which printer is nicer.

Flaw family 8: THE RULE RUN BACKWARDS. Example: an advertisement says anyone who loves puzzles will love the game Gridlock. Tess hears that Leo can't stop playing Gridlock and concludes he must be a puzzle fan. The advertisement only promises that puzzle fans are inside the Gridlock-lovers circle; it never says the circle contains nobody else. Leo could love Gridlock for its music, its colours or its speed and dislike every other puzzle. The winning option says the game may appeal to people who don't normally like puzzles. You will meet the same backwards move in 'Whose reasoning' questions — a rule of the form 'whenever A, then B' never lets you go from B back to A.

Eight families cover nearly every mistake question. (1) More than one match. (2) Minimum ≠ guarantee. (3) Forgotten possibility. (4) My experience says otherwise — a small group can't disprove a statistic. (5) Same time, so it caused it — a rival cause was ignored. (6) This cause, so not that one — both can be true. (7) The comparison left something out. (8) The rule run backwards. The routine never changes: read the speaker's conclusion, name the jump in your own words, then scan the options for the sentence that names the same jump. Beware options that are true but harmless — the flaw-namer, not the fact-stater, is your answer. Quiz and exercises!