This paper is about a thoroughly discredited but tenacious categorical error within the contemporary study of Islamic history. Namely, there is something fundamentally incompatible about Sufism and Islam. This idea developed from and endures through a specific set of post-Enlightenment associations that link Islam with rational legal discourse, and Sufism with non-rational spirituality or mysticism. Historians have worked to correct this mistake by historicizing the basic categories and the contingency of their association. Nevertheless, the idea persists, implicitly and stealthily, because we cannot escape the conceptual pull of the primary categories defining the modern study of Islam. That enterprise was founded upon the categorical distinction that divides Islamic history into rational and non-rational elements. Attempts to stitch these pieces back together have produced hybrid categories (practical, juridical, or philosophical Sufism, e.g.) that, while useful, still depend upon and reproduce the division in new form. To quote Spivak, “What taxonomy can fix this space?” In response, I propose the artificial taxon “bureaucratic Sufism” – not as a means to fix this space but to describe and analyze it more precisely. I derive the characteristics of bureaucratic Sufism from documents produced by the Ayyubid and Mamluk bureaucracies: endowment deeds for Sufi hospices and documents of investiture for the stipendiary posts therein. I then turn to contemporaneous literary texts that describe or critique those Sufis who lived in the hospices and competed for the posts. Citing brief examples from these texts, I argue that the fundamental debate about Sufism in this period was not its legitimacy but rather its character. More specifically, it was about the limits of Sufi identity and who had the power to make that determination. The various arguments on this subject were driven by specific material and social conditions: the proliferation of endowed hospices and stipendiary posts after the 12th century. Finally, I argue that early historians of Sufism and Islam doubly misidentified the nature of this debate as an ideological rupture between rational and non-rational epistemologies.