It is widely held that Aristotle presents two contradictory accounts of the best kind of tragic plot in chapters 13 and 14 of the Poetics. But an explicit cross-reference between the two chapters puts it beyond doubt that Aristotle regarded their conclusions as mutually supporting. Since Aristotle often expects readers to be willing to follow a prolonged and circuitous argument without drawing premature conclusions about his final conclusion, the first part of chapter 13 must be viewed as an interim stage in a complex exposition. The first part of chapter 13 contains lexical and logical anomalies, often overlooked, which provide pointers to Aristotle’s strategy in making a case against those who advocate double plots, and against those who reject plots that end in misfortune. Against these opponents Aristotle insists that plots that end in misfortune are not faulty, but not that such plots are required. The careful formulation of his initial conclusion, using grammatical forms that specify a trajectory of change rather than its end-point, leaves both possibilities in play. There is therefore no contradiction when, on emerging from the polemical context of chapter 13, he adopts an inclusive, rather than a narrowly exclusive, conception of the best kind of tragic plot and develops a graded hierarchy of the sub-types it contains.