Logical and Abstract Reasoning
What this domain tests
Logical and abstract reasoning covers deductive arguments, conditional statements, syllogisms, ordering and seating puzzles, coding, and figure series. For figure-series items, describe each rule in words: count of elements, rotation, shading, position, and addition or removal.
Core rules and concepts
- If P then Q: the valid inference is not Q therefore not P (the contrapositive). Q therefore P and not P therefore not Q are invalid.
- Only if: P only if Q means Q is necessary for P; P cannot occur without Q.
- All A are B does not imply all B are A. No A are B is reversible.
- Some means at least one, not some but not all.
- Use Venn diagrams to test syllogisms with overlapping categories.
- Ordering puzzles: translate each clue into an inequality or a fixed slot, then test the options against every clue.
- Figure series: track one feature at a time across the sequence.
Worked example
All inspectors are trained. Some trained staff are drivers. Therefore some inspectors are drivers.
Is the conclusion valid? No. The trained set contains all inspectors, and some drivers also sit in that set, but those drivers may lie entirely outside the inspector subset. The premises force no overlap between inspectors and drivers. A valid conclusion would be: all inspectors are trained.
Traps that cost marks
- Affirming the consequent: if it rains, the ground is wet; the ground is wet, so it rained.
- Denying the antecedent.
- Reversing all A are B.
- Treating some as excluding all.
- Ignoring one clue in an ordering puzzle.
- Assuming a figure sequence alternates when it actually increases by two.