Logical Reasoning
Logical Reasoning tests structured thinking rather than general intelligence. Common item types include syllogisms, blood relations, direction sense, seating arrangements, coding-decoding, number and letter series, statement-assumption, and cause-effect.
Core rules
- In syllogisms, draw Venn diagrams. "All A are B" does not convert to "All B are A". "Some A are B" is symmetric. "No A are B" is also symmetric.
- In formal logic, "some" means at least one; do not read it as "some but not all".
- For blood relations, build a family tree and mark gender only when the text gives it; do not infer gender from a profession.
- For direction sense, use coordinates: north = +y, east = +x. A left or right turn depends on the current facing direction.
- In seating arrangements, fix one anchor clue and use negative clues ("X is not next to Y") to eliminate possibilities.
- For series, check differences, ratios, squares, cubes, and alternating patterns before guessing.
- In statement-assumption, the assumption must be necessary for the argument, not merely plausible.
Worked example
All managers are leaders. Some leaders are coaches. Conclusion: Some managers are coaches. Draw the managers inside leaders. The coaches are some leaders; they may lie inside the manager subset or outside it. The premises do not force any coach to be a manager. The conclusion is not necessarily true, so it does not follow.
Traps
Converting "all A are B" into "all B are A"; treating "some" as "some but not all"; using real-world knowledge that contradicts the premises; ignoring the possibility of multiple valid arrangements; missing "either/or" cases in puzzles.