We can never do merely one thing.

Hardin’s aphorism captures a systems-ecology insight central to his work: interventions in complex social and environmental systems inevitably have multiple effects, including unintended consequences. The line cautions against single-issue thinking—whether in population policy, resource management, or technology—because actions propagate through interdependent networks of incentives, feedback loops, and shared commons. Read this way, the quote functions as a methodological warning: responsible decision-making requires tracing second- and third-order impacts, not merely achieving an immediate goal. It also implies moral responsibility for side effects, since “doing one thing” is an illusion created by narrow framing rather than reality.