Final answer:
Roosevelt's Four Freedoms speech aimed to persuade Americans to support U.S. involvement in World War II, against the prior policy of nonintervention. It presented a vision of a post-war world grounded in the Four Freedoms, setting the tone for the U.S. to aid in defeating totalitarian regimes and shape a peaceful future.
Step-by-step explanation:
The purpose of President Franklin D. Roosevelt's Four Freedoms speech was primarily to persuade Americans to accept U.S. involvement in World War II and to provide a vision for a post-war world founded on fundamental human freedoms. Roosevelt articulated a world that would be built upon the Four Freedoms: freedom of speech, freedom of worship, freedom from want, and freedom from fear. This vision was in direct opposition to the totalitarian ideologies that were spreading across Europe and Asia. Roosevelt's speech also sought to shift American public opinion towards support for the Allies, indicating a move away from isolationism and highlighting the need for U.S. support to ensure global peace and security.
Roosevelt made it clear that the events unfolding in Europe, notably the aggression of fascist countries, demanded a response. By painting a picture of a future world that would be free from dictatorial control and suffering, Roosevelt was asserting the need for a proactive American role in the ongoing global conflict. It was a departure from the U.S. policy of nonintervention and a call to the nation to support the war effort, including the request for funds to supply cash-strapped European countries with the necessary aid to continue the fight.