Anyone familiar with possibility theory and possibilistic analysis? I came across it during my own research on expert human reasoning/decision making. Here is a brief description of possibility theory from a recent article behind a paywall. As I see it, possibility theory offers a novel way to deal with chances which have some particular form of 'vagueness' to them. This makes it an alternative to probability theory, the standard canonical mathematical theory of chances, which focuses on randomness instead of vagueness. I'm not entirely sure if the two theories are exclusionary with respect to each other, or if they are in some sense just different ways of looking at the same thing, eg. like looking at classical mechanics from a Newtonian, Hamiltonian or Lagrangian perspective. In any case, possibility theory seems to be a powerful, and more importantly, intuitive tool, which seems to be a lot simpler to learn than probability theory and seems to more closely or more naturally model human reasoning than probability theory does.