Final answer:
Lyndon B. Johnson's speech is strengthened by his use of analogical comparison and the pathos appeal to highlight the need for true equality, beyond just legal rights, for marginalized groups.
Step-by-step explanation:
In his speech, Lyndon B. Johnson employs the rhetorical device known as analogical comparison, where he compares the newly acquired freedom of marginalized groups to entering a race after being hobbled by chains. This analogy strengthens the speech by vividly illustrating the injustice of expecting immediate, fair competition from individuals who have just been emancipated from societal constraints. Furthermore, Johnson utilizes the rhetorical appeal of pathos to connect emotionally with his audience, emphasizing the unfairness and enduring impact of discrimination. He conjures an emotional response that supports his call for not just legal equality but also equality in opportunity and result.