Logical and Abstract Reasoning
What this section tests
Formal and figural logic: syllogisms, blood relations, direction sense, seating arrangements, coding–decoding, series and analogies in figures, odd-one-out, statement–assumption, and Venn-based counting.
Methods
Syllogisms: draw the minimum diagram that satisfies the premises, then ask whether the conclusion is forced in every arrangement. Blood relations: draw a family tree, using separate symbols for male and female and a vertical axis for generations; never hold it in memory. Direction sense: sketch the path, remembering that turning left while facing south means facing east. Seating: anchor the most constrained person first and build outward.
Traps
- “All A are B” does not convert to “All B are A”; “Some A are B” does convert to “Some B are A”.
- Words such as only, unless, at least and none but change the logical form - underline them.
- In figures, distinguish rotation from reflection: a mirrored figure cannot be produced by rotation alone.
- In circular arrangements, “facing north” versus “facing south” reverses left and right.
- Do not import real-world knowledge into formal logic.
Worked example
All clerks are staff. Some staff are drivers. Does it follow that some clerks are drivers? No. Draw staff as a large circle containing clerks, with drivers overlapping staff but sitting entirely outside the clerk group. The premises remain true and the conclusion is false, so the conclusion is not valid.
Rule of thumb
If you can draw one arrangement where the premises are true and the conclusion false, the conclusion does not follow.