Which fallacy occurs when one infers what ought to be based solely on what is natural?

The naturalistic fallacy is a logical misconception that arises when one makes the claim that what is natural must also be what is good or right. This fallacy suggests that one can infer moral conclusions solely based on natural facts, leading to flawed reasoning. For instance, someone might argue that because certain behaviors or traits are observed in nature, they are inherently acceptable or desirable in human society. This reasoning ignores the complexities of moral and ethical considerations that go beyond mere natural occurrences.

The other options represent different types of fallacies: argumentum ad nauseum involves arguing a point through repetitive assertions rather than valid reasoning, post hoc ergo propter hoc pertains to false cause and effect relationships, while tu quoque addresses hypocrisy in arguments. None of these encapsulate the specific notion of deriving moral judgments purely from natural states, which is the essence of the naturalistic fallacy. Thus, the identification of the naturalistic fallacy is accurate in highlighting this specific logical error.