Every mental model you rely on was built during a period of uncertainty — and then froze. The 11th-century Persian physician Ibn Sina described something he called 'habit of the estimative faculty': the mind's tendency to calcify provisional judgments into permanent ones, not from laziness but from the genuine cognitive cost of re-opening settled questions. The problem isn't that your models are wrong. It's that they were right once, at a specific resolution, and the world has since changed granularity without notifying you. In product leadership, this shows up as the model that correctly explained why users churned in 2023 being silently applied to a market that has structurally shifted — not because you're incurious, but because working models feel like solid ground. Ibn Sina's prescription was periodic deliberate disconfirmation: take your most load-bearing belief and actively seek the case where it fails, before circumstances force it. The model doesn't need to be discarded. It needs a date stamp.

What is the oldest mental model you're still running in a domain that has visibly changed — and when did you last deliberately try to break it?

Drawing from Islamic Peripatetic Philosophy / Avicennan Psychology — Ibn Sina (Avicenna) (Kitab al-Shifa / The Book of Healing, c. 1027 CE)