Final answer:
Brutus uses the rhetorical device of anaphora, repeating 'If any, speak; for him have I offended' to underscore that his assassination of Caesar was meant to protect Roman freedom and values.
Step-by-step explanation:
The rhetorical device used in the bolded lines of Brutus's speech in Act 3.2 of The Tragedy of Julius Caesar is anaphora. Anaphora is a figure of speech where a word or phrase is repeated at the beginning of consecutive clauses or sentences. In this excerpt, Brutus repeats the phrase 'If any, speak; for him have I offended' to emphasize the message that his actions in assassinating Caesar were done in the best interest of Rome and its citizens. By posing these rhetorical questions, he challenges his audience to consider if anyone among them prefers slavery to freedom, a lack of Roman identity and values, or disloyalty to one's country, inferring that these would be the only reasonable objections to his actions against the ambitious Caesar.