On December 8, 1941, the day after the attack on Pearl Harbor, Franklin Delano Roosevelt delivered a speech to the vice president, the speaker of the House, members of the Senate, and of the House of Representatives, and to the American people. The attack on the Hawaiian islands was a shock to everyone, especially because the Japanese had appeared to be cooperating previously. Roosevelt uses ethos to appeal to his audience by his formality, his position, and his concise reasoning which all lead the U.S. to declare war.
The reasoning Roosevelt uses is simple and builds his credibility because he knows what he's talking about. He explains that “the United States was at peace with [Japan] and, at the solicitation of Japan, was still in conversation with its government and its emperor looking toward the maintenance of peace in the Pacific” (par. 2). This is backed up with proof in the next paragraph about the U.S. receiving a letter from Japan an hour after the attack that contained no threats of war. Roosevelt continues to clarify the situation as he discusses the immediate effects of the attack. Also discussed are the other attacks Japan made in the same day. The specific names and places and details all work together to build his credibility.
Along these lines, Roosevelt speaks with clarity and formality to build the ethos of his argument for declaring war. He address the important leaders in the government in an official way. As he speaks, he uses formal language to reinforce his position and the fact that he knows what he's doing. FDR doesn't sugar-coat anything or beat around the bush. He just states things how they are. An example of this is when he says “The attack yesterday on the Hawaiian islands has caused severe damage to American naval and military forces. I regret to tell you that very many American lives have been lost” (par. 5). He keeps the speech focused and just shares the reality of the situation. This formality establishes his credibility and makes him sound like someone who should be listened to.
However, Roosevelt already had ethos on his side because of his rank. At the time, he was president of the United States of America. This is a very high position and people usually listen to the president. He also is “commander in chief of the Army and Navy” and specifically uses this to remind the audience of his status and place (par. 8). However, Roosevelt doesn't place himself too far about the regular people of America. He uses phrases like “our whole nation” and “no matter how long it may take us” and “we will gain the inevitable triumph” to include himself in the whole of America (par. 8, 9, 12). This keeps him credible but also doesn't distance him from the audience too much.
All of these tactics help build the ethos of his speech. Roosevelt presents himself as a credible person with moral character who should be paid attention to. The formality, clarity, and clear reasoning, along with his position as president of the United States, establish him to be the person he is and gives him great influence. It would be difficult to not declare war after a person like Roosevelt presents such a solid argument.