All imaginable futures are not equally possible.

Kelly’s line pushes back against the idea that the future is an open, uniform field where any scenario we can picture has the same chance of occurring. It suggests that constraints—physical laws, technological path-dependence, economic incentives, institutional inertia, and cultural habits—shape a “space of possibilities” in which some outcomes are far more reachable than others. The quote also implies a practical stance toward forecasting: imagination is necessary, but it must be disciplined by an understanding of constraints and trajectories. In this view, good futurism is less about inventing arbitrary possibilities and more about identifying which possibilities are adjacent, enabled, or foreclosed by present conditions.