P1. If today is February 29th, then it is a leap year P2. Today is not February 29th C. It is not a Leap Year Is this argument sound or unsound? From what I can tell it is invalid because it is possible for it to be a leap year and today not being February 29th. If it’s invalid then it should be unsound. However neither of the premises are false so it can’t be unsound? Even if it were sound, wouldn’t it technically become unsound if it happened to be February 29th in real life?

The argument is unsound because, as you say, it's invalid. It commits the well-known fallacy of denying the antecedent.

Validity is necessary (but not sufficient) for soundness. So the argument is unsound regardless of the truth or falsity of its premises.

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