Answer:
Ethos
Explanation:
Ethos, also known as Credibility or Ethical Appeal is a reference to the authority and suitability of a person to preside over a matter. This appeal is one of the three appeals (Ethos, Pathos, and Logos) used to help speakers win an argument. Ethos cites the position or qualification of a subject to instill confidence in the audience that a position which they support should be believed.
When John Adams mentioned the positions of Kings, Ministers, Ancestors, and the whole nation, he thus wants the audience to believe that the consequence was valid because these notable personalities endorsed it.