A common sense approach to dissecting charismatic rhetoric from rationality might be:
1. Using deductive and inductive reasoning to pierce the veil of rhetoric. Deductive reasoning arrives at a specific conclusion based on generalizations. While, Inductive reasoning takes events and makes generalizations (Trochim 2006). Whether the generalizations come at the end of a case (Inductive) or in the beginning (Deductive), it is important to follow the logical connection between the generalizations as well as the factuality of the generalizations.
2. Thinking within a principle-centric reality. Philosopher Ayn Rand (Peikoff 1982) encouraged critical thinking through principles or overarching ideas of an argument. For example, if a person believes humans are created in the image of God, the person is operating from a principle that he believes a higher power created individuals and would necessarily reject the idea of Darwin's "Evolution." Principles often reflect paradigms. If one can understand someone's mode of thinking, he may see reality through another's lenses, but still maintain his own reasoning.
3. Separating emotions from reasoning. Former President Bill Clinton was known for his ability to compartmentalize his emotions. He could be embroiled in a personal scandal on one hand and focused on foreign policy on another. To him, one thing had nothing to do with the other. Being inspired about the message and metaphors of a political message may garner hope, but emotionally driven hope should never become a substitute for rational public policy.
Peikoff, L. (1982). The Ominous Parallels. New York. Penguin Group.
Trochim, W. (2006). Deductive and Inductive Reasoning. Research Methods Knowledge base. Retrieved from: http://www.socialresearchmethods.net/kb/dedind.php