Where do we find rationality when the environment does not independently influence outcomes or even rules of the game (Weick, 1979), the future is truly unpredictable (Knight, 1921), and the decision maker is unsure of his/her own preferences (March, 1982)? This essay argues that the creation and growth of enduring and innovative firms can be explained, at the core, by an empirically grounded model of a process called effectuation, combined with a structural feature of near-decomposability in complex systems that can speed up their evolution. Just as effectuation creates rapidly evolving artifacts that leverage interdependence to exploit locality and contingency, so near-decomposability in the structure of such systems leverages independence to exploit the same locality and contingency.