The "adjacent possible" describes the open space of direction that the future may take—the realm of the possible that is available at a given moment. Greater change is possible, but unlikely to extend beyond the adjacent space. Innovation doesn't happen in leaps and bounds, but occurs through small, incremental steps. When ideas skip too far ahead beyond the "adjacent possible," they're unlikely to be adopted in the short-term. This is what we would call an idea that is "ahead of its time." They've skipped too far past the adjacent possible.
Steven Johnson borrows the idea of the "adjacent possible" from Stuart Kauffman, who used the term to describe how simple biological systems make small, incremental steps toward becoming complex systems.
A somewhat related notion is that of a "proximate objective," used by Richard Rumelt to describe an objective that is close enough so as to be feasible.
- § Innovation: different approaches and models to innovation, which relies on the adjacent possible for viability