Final answer:
President Roosevelt's rhetoric aimed to highlight the dangers of inaction, reinforce America's historical commitment to democracy, and convince Americans that joining WWII was necessary for moral and national security reasons.
Step-by-step explanation:
President Franklin D. Roosevelt's rhetorical appeals during World War II had several intended effects. One effect was to describe for Americans the potential dangers of not joining the war. By emphasizing the threats to democracy posed by the Axis powers and the economic downturn, Roosevelt aimed to clarify the severe risks of inaction. Another intended effect was to remind Americans that they have always stood and fought for democracy. This appeal to historical precedent served to reinforce the nation's identity and its global responsibilities. Finally, Roosevelt's rhetoric was designed to convince Americans that joining the war was the absolute right thing to do. By arguing that the struggle was essential to the nation's principles and future security, he sought to align the public's moral compass with the war effort.