Ethics & foresight
Long-termism
Definition
Long-termism is the ethical position, developed within the effective altruism movement by philosophers such as Toby Ord and William MacAskill, that the primary determinant of an action's value is its effect on the very long-run future. Because vast numbers of future people could exist, safeguarding humanity's long-term potential — especially against existential risks — is argued to be a central moral priority.
References
Supports definition and framing.
Supports definition and framing.
Overview
What it means
The view combines moral impartiality toward future generations with expected-value reasoning about large-scale, low-probability risks (AI catastrophe, engineered pandemics, extreme climate change) and opportunities to shape civilisational trajectories.
How it is used
Long-termism informs philanthropy, research agendas and policy advocacy on existential risk, biosecurity and AI governance, and connects to sustainability debates on intergenerational equity — though critics warn it can discount present-day suffering and near-term environmental harms.
Why it matters
It has become influential in how substantial philanthropic and research resources are allocated toward long-horizon risks, making it a live concept in sustainability and futures ethics discussions.