Analytical Reasoning: Rules, Diagrams, and Valid Deduction
Core concepts
Analytical Reasoning presents a set of entities, a fixed number of slots or groups, and conditional rules. You must determine what must be true, what could be true, and what cannot be true. The essential tools are a compact diagram (an ordered line for sequencing, a table for grouping), symbolic notation for rules (A → not B), and the contrapositive (B → not A). Know the difference between sufficient and necessary conditions: "if A then B" does not license "if B then A".
Traps
The classic error is reversing a conditional or denying the antecedent. From "If A is selected, B is not" together with "B is not selected", you cannot conclude that A is selected. Quantity words matter: some means at least one, not all; none and all are strong and easy to over-apply. Questions asking what could be true are satisfied by any legal arrangement, so do not hunt for a single forced answer. Watch also for rules that chain: A → B and B → C give A → C, a deduction many candidates miss.
Rule of thumb: eliminate aggressively
Draw the diagram, write every rule, then test each answer choice against the rules. The first choice that violates a rule is out; the correct answer to a "must be true" question is the one that no legal arrangement can contradict.
Worked example
Five students - P, Q, R, S, T - sit in a row. Rule: P sits immediately before Q. If Q is in seat 3, P must be in seat 2, so seats 1, 4 and 5 hold R, S and T in any order. Any option placing R in seat 2 is therefore impossible.