Every project plan is a theory. The moment you publish a schedule, you have written a hypothesis about how the future will unfold — and like any hypothesis, its value lies not in being right but in being falsifiable. The 11th-century Islamic logician Ibn Hazm of Córdoba made a distinction that project managers rarely encounter but badly need: he separated *al-qat'* (certain knowledge, derived from direct observation) from *al-zann* (probable opinion, derived from inference). His argument was that confusing the two is not just an intellectual error — it is a moral one, because it leads you to treat conjecture with the authority of fact. Most project plans are almost entirely *zann* dressed up as *qat'*: inferred durations, assumed dependencies, guessed resource availability, all rendered in a Gantt chart that implies a precision the underlying data cannot support. The practical correction is not to plan less carefully but to mark your uncertainties differently — to treat 'we have done this exact task before and logged the time' as genuinely different evidence from 'we think this will take about two weeks.' When you distinguish the category of your confidence, not just the degree, you stop over-defending the estimates you should be revisiting first.

In your current project, which estimates are based on actual logged data from comparable past work — and which are inferences you've stopped labeling as such?

Drawing from Andalusian Islamic logic and epistemology (Zahiri school) — Ibn Hazm of Córdoba (Al-Ihkam fi Usul al-Ahkam / Mastery of the Principles of Legal Reasoning, c. 1027–1034 CE)