Logical Reasoning and Analytical Ability

What the official syllabus says

Preliminary Examination, General Studies Paper II:

• Logical reasoning and analytical ability;

Logical reasoning tests whether a conclusion follows from given statements. Analytical ability tests whether a candidate can organise a set of conditions (who sits where, who comes first, which combination is possible) and draw every valid consequence from them.

Topics in detail

Deductive logic

• Syllogisms: statements with "all", "some", "no" and "some not"; which conclusions follow.
• Venn diagram method for syllogisms; "either-or" pairs of conclusions; "possibility" cases.
• Conditional statements: "if P then Q", its converse, inverse and contrapositive; which of them are equivalent.
• Necessary and sufficient conditions; "only if", "unless" and "if and only if".
• Logical connectives: "and", "or", "not"; negation of "all" and "some" statements.
• Truth-teller and liar puzzles; consistency of a set of statements.

Arguments and critical reasoning

• Statement and assumption: which unstated premise is implicit.
• Statement and conclusion: which conclusion follows definitely.
• Statement and argument: strong and weak arguments for and against a proposal.
• Statement and course of action: which action follows as a practical response.
• Cause and effect: identifying the cause, the effect and independent events.
• Strengthening and weakening an argument; finding the flaw in reasoning.
• Analogy of reasoning: an argument with the same logical structure as the given one.

Arrangements and puzzles

• Linear seating arrangement: one row or two rows facing each other.
• Circular and square arrangements: facing the centre or outwards; left and right of a person.
• Ordering and ranking: positions from the top and the bottom; taller, heavier, older comparisons.
• Scheduling puzzles: days of the week, months, floors of a building, time slots.
• Grouping and selection: forming a team or committee under conditions ("A must go with B", "C cannot go with D").
• Matching puzzles: persons with professions, cities, colours or subjects, using a grid.
• Questions asking what must be true, could be true or cannot be true under the conditions.

Relations and directions

• Blood relations: family trees, coded relations ("A + B means A is the father of B").
• Direction sense: the cardinal and intermediate directions, turns, net displacement and shadows at sunrise and sunset.
• Distance in direction problems using the Pythagoras theorem.

Analytical reasoning with figures and sets

• Venn diagrams showing the relation between classes (for example, doctors, women and graduates).
• Counting from Venn diagrams: elements in exactly one, two or all three sets.
• Logical data sufficiency: whether given statements are enough to answer a question.
• Inequalities with symbols: combined statements such as P > Q ≥ R and which relations follow.

Method

• Writing each condition in short form and drawing the arrangement before reading the questions.
• Starting with fixed information, then conditions that link two people, then negative conditions.
• Testing each option against all conditions rather than assuming.

Overlaps

• Assumption and inference questions in Comprehension use the same reasoning.
• Series, coding and figure puzzles are covered under General Mental Ability, and numerical data sufficiency under Data Interpretation.