According to the currently favoured view among historians of the Persian Empire, the Bīsotūn Inscription is a deceitful piece of propaganda whose purpose was to resolve Darius’s legitimacy problem. To this effect, Darius cobbles a family relation with Cyrus and fabricates the story of a magus who impersonates Smerdis, son of Cyrus, and usurps the throne. This view, however, contradicts not only the Bīsotūn Inscription but also the ancient Greek testimonies. This article examines the arguments historians have given for their position. Since all views of the two issues in question are necessarily interpretations of the relevant sources that rely on argumentation, reasons and inferences must stand up to critical scrutiny.