An argument based on logic and reason rather than emotion and personal opinion is best described as objective. rhetorical. biased. weak.

Objective.

Explanation:

An objective approach to an argument is one that is based on logical rules of argumentation founded on principles of reason, aiming at stating facts and accurately conveying perspectives and information upon a given problem or question that one wishes to shed light upon. Objective stands as opposite to subjective, which would be an argument based on personal coordinates, like feelings, taste, or emotion.  

after the moon goes from a full moon it turns into a waning gibbous moon.

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