Credibility
There are three basic rhetorical strategies that can appeal to a person’s logos, pathos, and/or ethos. The rhetorical strategy that appeals to one’s logic is called logos. The rhetorical strategy that appeals to one’s emotions is called pathos. The rhetorical strategy that references the moral/ethical standing (trustworthiness/credibility) of the speaker is called ethos. That said, because the quotation is based upon the fact that slaves should be because it is by order of the president, and the president of the United States is one whom is deemed trustworthy, the rhetorical strategy you would be using would be that of credibility/ethos.
