Part I of my two-part conversation with Jonathan Kirshner about his new book, An Unwritten Future: Realism, Uncertainty, and World Politics. Kirshner explains why classical realism is a misunderstood intellectual tradition. We get into: Why realism recruits dead people into their intellectual tradition; what we can learn from Thucydides, and why an armchair understanding of the Peloponnesian War does more harm than good; why realist pessimism is a self-fulfilling prophecy; why international relations has somewhat lost its way; how we should think about the “national interest"; and distinctions between realist and progressive political economy.