Hey
Currently struggling through an exercise on definitions in truth-functional logic. Anyone any good with the below question? I'd appreciate it so much!
Say whether the following statements are true or false, giving reasons for your answers:
(i) If the sentence X is a tautology, and the inference from X to Y is truth-functionally valid, then Y is also a tautology.
(ii) If the sentence Y is a tautology and the inference from X to Y is truth-functionally valid, then X is also a tautology.
(iii) If the sentence X is a contradiction, and the inference from X to Y is truth-functionally valid, then Y is also a contradiction.
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