Mensa IQ Syllogisms and Logical Arguments Flashcards

All squares are rectangles. All rectangles are parallelograms. Which conclusion is VALID?

Answer: All squares are parallelograms

Barbara (AAA-1): All S→R, All R→P, therefore All S→P.

Some birds cannot fly. All penguins are birds. Which conclusion is DEFINITELY valid?

Answer: All penguins are birds

The only statement that necessarily follows from the given premises is the second premise itself: all penguins are birds.

No vegetarians eat meat. Jane is a vegetarian. Therefore:

Answer: Jane does not eat meat

Jane ∈ vegetarians, and no vegetarian eats meat → Jane does not eat meat.

All politicians are public speakers. Some liars are politicians. Which conclusion follows?

Answer: Some liars are public speakers

The liar-politicians are public speakers (all politicians are public speakers) → some liars are public speakers.

Premise 1: If it rains, the ground gets wet. Premise 2: The ground is wet. What can we conclude?

Answer: It may or may not have rained

Affirming the consequent is a fallacy — wet ground could have other causes; we cannot conclude it rained.

All A are B. No B are C. Which conclusion is VALID?

Answer: No A are C

EAE-2 (Cesare): All A→B; No B→C; therefore No A→C.

Some cats are black. Some black things are cars. Which conclusion MUST follow?

Answer: Nothing must follow

Two particular premises (II) yield no valid syllogistic conclusion — the overlap of 'cats∩black' and 'black∩cars' may not intersect.