Chapters 12 and 13 of the De Interpretations present some puzzles, which it is my purpose to try to solve. The latest commentator, Professor Jaakke Hintikka, attempts in Acta Philosophica Fennica xiv (1962), 5–22, to abolish the difficulties by taking certain verbs in an unusual way. He suggests that in these chapters , which is usually taken to denote logical consequence, sometimes expresses simply compatibility (21b35–22a1, 22b11–14, 22b17–22), sometimes equivalence (22a14 and 33, 22b22ff., 23a18ff.), and that at 22a38ff., 22b3O, and 23a17 , which again is usually taken to denote consequence, in fact expresses compatibility. I propose to counter Hintikka's arguments and to maintain that both verbs express consequence; but as my main purpose is to give my own explanation of the general trend of Aristotle's remarks, I shall take the passages discussed by Hintikka in the order in which they occur in Aristotle's text.