The theory of syllogism, which forms the basis of Aristotle’s logic offers us a system in which the propositions (premises and conclusion) that make it up are not in a conditional structure, but only in a categorical structure. Aristotelian logic has a formal identity that examines the inferences between categorical propositions. The fact that the conditional structures, whose first examples we come across in the logic of his pupil Theophrastos and Stoics, are not included in Aristotle can be regarded as a deficiency for him, considering his title of being the systematic founder of logic. However, the syllogistic established by Aristotle is not completely separate from the hypothetical elements. As a form of inference, reductio ad absurdum, is a hypothetical method that Aristotle uses. In this article, where we look for the reasons why Aristotle did not include conditional elements in the basis of a proposition or syllogism, our primary goal is to make the distinction between conditional and hypothetical concepts clear. If this distinction is not taken into account, we claim that Aristotle’s understanding of syllogism will be mistaken for a conditional structure. Subsequently, we will discuss why the syllogisms formed with hypothetical propositions are not accepted as syllogisms by Aristotle, based on his distinction between probative and hypothetical syllogisms.