Argument #1, a simplified reconstruction of Plato’s argument in the Republic in favor of censorship of the arts.
Premise 1. The state should prohibit the publication of any poetry that grossly violates the truth of divinity or tends to weaken human character.
Premise 2. Poetry that portrays divinities as committing murder, adultery, or other morally repulsive acts, or portrays heroes as flooded by cowardly emotion, is poetry that grossly violates the truth of divinity or tends to weaken human character.
Conclusion. Therefore, the state should prohibit the publication of any poetry that portrays divinities as committing murder, adultery, or other morally repulsive acts, or portrays heroes as flooded by cowardly emotion.
Summary analysis of argument #1. Although, according to the standards of logic, the conclusion does follow from the premises, premise 1 is false, a fatal flaw in the argument.
Argument #2, a simplified reconstruction of an argument against proposing divine standards of truth, beauty, and goodness.
Premise 1. Plato held that there are eternal standards of excellence and that poetry should be in harmony with those standards.
Premise 2. Plato advocated censorship of the arts, a totalitarian betrayal of human liberty.
Conclusion: Therefore, claims to eternal standards of excellence are to be suspected of being totalitarian.
Summary analysis of argument #2. Both premises are correct, but the conclusion does not follow. Therefore, the argument is invalid. (Note: in logic, validity and invalidity are properties of arguments, not of individual propositions, which may be true or false.)