This two-part paper reviews a scholarly debate on an alleged tension in Frege's philosophy of logic. In Section 1 of Part I, I discuss Frege's view that logic is concerned with establishing norms for correct thinking and is therefore a normative science. In Section 2, I explore a different understanding of the role of logic that Frege seems to advance: logic is constitutive of the very possibility of thought, because it sets forth necessary conditions for thought. Hence, the tension the (...) view according to which logic is normative for thought seems to be incompatible with the idea that abiding by the laws of logic forms a precondition for thought. In Section 1 of Part II, I survey a number of interpretations of Frege's conception of logic that deal with this question. I show that they are for the most part either normative readings (emphasising the former understanding of the nature of logic) or constitutive readings (emphasising the latter). Finally, in Section 2, I adjudicate the debate and aim at reconciling the normative and the constitutive strands in Frege's conception of logic. (shrink)