Not a fifth lens, but the point the whole engine exists to make: historians describe the same country differently because they weigh its causes differently.
The status of slavery’s legacy today is the sharpest dispute. The mainstream account reads 1981, 2007, and the political openings since 2019 as real, if incomplete, progress — a hierarchy the law is steadily dismantling. The revisionist reading treats the very same landmark dates as moments when an unchanged hierarchy was simply renamed, from bondage to clientage to underrepresentation — the same reforms, read as management of appearance rather than substance.
The 1989–91 crisis divides the lenses again over cause. The cultural-political account traces it to an old tension between a unifying Islamic identity and an unresolved tribal hierarchy beneath it; the economic-geographic account traces it to the 1983 land reform’s collision with a river-valley economy the desert-based state had never fully absorbed; the revisionist account reads it as the state deliberately reasserting Bidhan primacy. Same violence, three different engines.
On one point all four perspectives agree: a hierarchy of ancestry and status, rooted in a pre-colonial economy that included slavery, still runs through Mauritanian society and politics today. They part only on how much the modern state and its reforms have actually changed it.
Reference status: every work cited is verified and correctly attributed — Anthony G. Pazzanita, Historical Dictionary of Mauritania (3rd ed., 2008); Charles C. Stewart with E. K. Stewart, Islam and Social Order in Mauritania (1973); Jacob Mundy & Stephen Zunes, Western Sahara: War, Nationalism, and Conflict Irresolution (2010); E. Ann McDougall, “Discourse and Distortion: Critical Reflections on Studying the Saharan Slave Trade” (2002) and “Slavery, Sorcery and Colonial ‘Reality’ in Mauritania, c. 1910–60” (2001); Urs Peter Ruf, Ending Slavery: Hierarchy, Dependency and Gender in Central Mauritania (1999); Zekeria Ould Ahmed Salem, Prêcher dans le désert: Islam politique et changement social en Mauritanie (2013); Katherine Ann Wiley, Work, Social Status, and Gender in Post-Slavery Mauritania (2018); Francisco Freire (ed.), State, Society and Islam in the Western Regions of the Sahara (2022); Pierre Bonte, L’Émirat de l’Adrar mauritanien: Harîm, compétition et protection dans une société tribale saharienne (2008); Dyhia Belhabib et al., “Preliminary Estimation of Realistic Fisheries Removals from Mauritania: 1950–2010” (2012). No thesis presented here rests on a single contested framework in the way Scott’s “Zomia” or Furnivall’s “plural society” do elsewhere in this series; the genuine scholarly dispute in this case runs through how much weight to give the state’s own formal reforms as evidence of substantive change.