Rhetorical devices refer to aspects of language that are intended to persuade the reader or promote discussion about a particular topic. Among the many rhetorical devices that Jared Diamond uses in Guns, Germs, and Steel, logos, which refers to an appeal to logic or reason, is prominent. Diamond also employs rhetorical questions, parallelism and other forms of repetition, and metaphors.

The use of logos dominates the whole book because Diamond’s primary intention is to convince the reader that his arguments are correct. In the prologue, Diamond states his intention to uncover reasons for social inequality, focusing on technology. He establishes a set of comparisons and contrasts between “[p]eoples of Eurasian origin” and “other peoples.” The groups he juxtaposes to Eurasian origin peoples are those of Africa, Australia, and the Americas.

At the end of the prologue, Diamond raises a set of rhetorical questions—the kind that are often intended to stimulate discussion rather than elicit a specific answer. Diamond provides rhetorical questions that he anticipates readers will pose; these questions may indicate challenges or opposition to his line of reasoning. In presenting these questions, he also uses parallelism, as he phrases them to elicit a negative answer: “Doesn’t it seem to say…”; “doesn’t [it] automatically involve…”; “don’t words such as ‘civilization’… convey the false impression…?”

Hyperbole is extreme exaggeration to make a point. Diamond uses hyperbole to call attention to unlikely or impossible situations. In chapter 1, discussing the earliest peopling of the Americas, he states, “Early humans certainly didn’t fly by helicopter….”