Final answer:
The rhetorical device used in Tim O’Brien's quote is parallelism, which involves repeating patterns of words to highlight the equivalence of two ideas.
Step-by-step explanation:
The quote by Tim O’Brien, ‘To generalize about war, is like generalizing about peace - almost everything is true, and almost nothing is true.’ is an example of parallelism. This rhetorical device involves the repetition of the same pattern of words or phrases to show that two ideas have the same level of importance. In the quote, the construction ‘is like generalizing about’ is repeated, creating a balance between the concepts of war and peace, thus highlighting the complexity and contradictory nature of generalizations about these vast topics.