Retrospective determinism

Biological Parallel

The pathway from tetrapod ancestor to modern mammals appears inevitable in retrospect, but the K-T extinction that cleared ecological space for mammalian radiation was a contingent asteroid impact. Stephen Jay Gould's "replaying life's tape" thought experiment: rerun evolution from the Cambrian and you'd likely get radically different outcomes. Historical contingency—random mutations, asteroid timing, climate shifts—means evolutionary paths are only determined after they're taken.