Final answer:
Barack Obama's argument in his 2009 Inaugural Address was effective due to its powerful and inspirational messages, such as his commitment to unity and equality.
Step-by-step explanation:
The effectiveness of Barack Obama's argument in his 2009 Inaugural Address can be evaluated by analyzing the content, rhetoric, and impact of the speech. Obama's speech was highly praised for its powerful and inspirational messages. For example, he expressed his commitment to unity and collaboration by stating, 'The time has come to reaffirm our enduring spirit, to choose our better history, to carry forward that precious gift, that noble idea passed on from generation to generation: the God-given promise that all are equal, all are free, and all deserve a chance to pursue their full measure of happiness.' This statement appeals to the values of equality and freedom, and serves as evidence of Obama's persuasive argument.