To convince listeners that Kennedy has thoroughly studied the history of the United States
Explanation:
To speak about something, the speaker should study the subject he wishes to address. This conveys credibility and conveys to the audience security about the information being passed, because it shows that the speaker knows well the subject being addressed. For this reason Kennedy referred to William Bradford before summarizing the point of condensed history. In making this reference, Kennedy showed that he studied the history of the United States deeply and this shows that he is the appropriate person to address this subject.
