Redundancy is usually treated as waste — duplicate systems, backup processes, overlapping roles. Management theory has spent decades trying to eliminate it. But the ecologist C.S. Holling, studying why some ecosystems survive catastrophic shocks while others collapse, found that biological resilience depended almost entirely on redundancy: multiple species performing the same function, so that when one disappeared, the system didn't fail. He called this 'functional redundancy,' and it turns out to be the hidden architecture of anything that survives. The mental models most professionals carry are the opposite of this. They're lean, non-overlapping, efficient — one model per problem class. That's fine in stable conditions and catastrophic when the conditions change, because the single model that explained everything before now explains nothing, and there's no backup. The implication for how you build your own thinking toolkit is uncomfortable: some of your models should be redundant on purpose. Not as a hedge against being wrong, but because a second model explaining the same phenomenon from a different angle is the only thing that tells you which features of the first model are essential and which are artifacts of its assumptions. A model you've never contradicted with another model is not knowledge — it's a habit with better branding.

Pick one mental model you use constantly and trust completely — what would a second, structurally different model for the same situation show you that the first one cannot?

Drawing from Ecological systems theory / Resilience theory — C.S. Holling