Answer: He provided evidence by quoting the beliefs that past leaders had when it came to "America's dream", such as the difference in opportunities for different classes, economic inequality, and unemployment. It is enough evidence since he discerns many facets of the same topic and recalls facts rather than just words.
Explanation: Jon Meacham brought to the table a reality instead of a fantasy. He claimed that the American Dream may be slipping away due to the numerous issues society has to face, such as the unfair social difference that brings more opportunities to only a few people, or the poor economical status that is caused by unemployment. His evidence is enough since he dismisses politician's "fake" speeches of hope and provides a more realistic point of view.
