We are making decisions right now — about climate, about genetics, about AI, about nuclear waste, about the species we drive to extinction — whose consequences will outlast us by generations. The people who will bear those consequences have no voice, no vote, and no veto. What obligations, if any, do we have to them?
The philosophical difficulty is foundational. Most ethical frameworks are built around relationships between people who exist. We can ask what we owe each other because "each other" is identifiable. Future people are not. We do not know who they are, what they will value, what problems they will face, or what technologies they will have. Making decisions on their behalf requires assumptions about a future we cannot predict — in a world where the book's Complexity and Unintended Consequences framework tells us prediction is unreliable.
The practical difficulty is equally severe. Political systems operate on short time horizons. Elected officials face voters every few years. Corporate leaders face quarterly earnings. Even well-intentioned institutions struggle to weigh costs that will be borne by people who will not exist for decades against benefits that accrue now. The incentive structures of human institutions are profoundly biased toward the present.
And the decisions are irreversible. Carbon emitted now will warm the atmosphere for centuries. Species driven to extinction are gone permanently. Heritable gene edits propagate through all future generations. Nuclear waste remains dangerous for millennia. Geoengineering programs, once started, create termination risks that bind future generations to maintenance. AI training data shapes the information environment that future generations will inherit. Each of these creates a form of obligation — or at minimum a form of consequence — that extends far beyond the people making the decisions.
Intergenerational Responsibility is one of the book's most distinctive ethical themes. It appears most powerfully in the discussion of The Day After Tomorrow, where the consequences of climate inaction cascade across generations, but it threads through many chapters. The book argues that technologies with long-lasting consequences create obligations that current decision-makers cannot discharge by simply maximizing present benefit.
Too Valuable to Fail — the Collingridge dilemma — is relevant in a specific way here. Many intergenerational risks arise precisely because a technology was too promising, too economically valuable, or too strategically important to constrain when constraining it was still possible. By the time the consequences become clear, the technology is entrenched.
The book's Resilience and Adaptation framework offers the most practical guidance. If we cannot predict the future, we can at least try not to foreclose it. Policies and technologies that maintain options, preserve biodiversity, avoid irreversible commitments, and build adaptive capacity are — almost by definition — more responsible to future generations than those that optimize for present benefit at the cost of future flexibility.
This may be the hardest question in this entire collection, because it has no satisfying answer. We cannot fully know what we owe people who do not exist. But recognizing the question — taking it seriously rather than leaving it unasked — is itself a form of responsibility.