UGC NET Questions (Paper – 1)

A tautology is a formula that evaluates to true on every row of its truth table, regardless of how its component propositions are valued. Its truth depends purely on its logical form, not on any contingent facts. Tautologies serve as logical truths that cannot be denied without inconsistency. Thus the compound statement described in the stem is a tautology.

Option A:
Option A, contradiction, is the opposite extreme: a statement that is false under every possible valuation. It cannot ever be true, which does not match the always-true condition in the question. Therefore contradiction is not correct.

Option B:
Option B, contingency, may be true under some valuations and false under others. Its truth is not fixed across all possibilities, so it fails to meet the "true under every" condition. Thus contingency is not appropriate here.

Option C:
Option C, paradox, is an informal term for statements that seem self-contradictory or counterintuitive but may contain a deeper truth. Paradoxes are not defined simply by their truth table behaviour. Consequently paradox does not answer the question.

Option D:
Option D is correct because tautology exactly captures the notion of a statement that cannot come out false on any truth-value assignment. Such statements are central to proofs and equivalence tests in logic.

A tautology is a statement that is true under every assignment of truth values to its components. Its truth is guaranteed by its logical form alone. Such statements are logically necessary and cannot be false. Therefore the description in the stem matches the concept of a tautology.

Option A:
Option A, contradiction, is always false under every possible valuation. It represents the opposite logical extreme from a tautology. Hence contradiction does not fit the stem.

Option B:
Option B, contingency, is a statement that is true under some valuations and false under others. Its truth is not fixed across all possibilities. Therefore contingency is not the correct answer here.

Option C:
Option C correctly names tautology as the always true compound statement described. Tautologies play an important role in logical equivalence and proof. Thus tautology is the appropriate choice.

Option D:
Option D, paradox, refers informally to a statement that seems self-contradictory or absurd yet often reveals a truth. It is not defined as a statement true in all valuations. Consequently paradox is not suitable here.