Final answer:
The Greek word for logical, rational argument is 'logos,' which signifies reason and evidence-based argumentation, and is an essential concept in the art of persuasion, rhetoric.
Step-by-step explanation:
The Greek word for a logical, rational argument is logos. This term encompasses the concept of reason, logical thinking, and evidence-based arguments, as opposed to mythos which signifies mythical or supernatural storytelling. The transition from mythos to logos represents a move from religious and mythological explanations to ones based on reason and scientific understanding. Ancient Greek philosophers like Aristotle utilized logos to develop persuasive arguments through rhetoric, which includes ethos (ethics), logos (logic), pathos (emotions), and kairos (timeliness). In philosophical and religious contexts, logos also referred to the divine principle of order and knowledge, understood by the Stoics as the divine 'Word' or guiding force of the universe.