  Ramsey considered a world with an indefinite future. This could appear to be an odd move, but it has a strong rationale. Suppose DM were to choose a horizon of \(T\) years. As she doesn’t know when our world will end, she will want to specify the resources that should be left behind at \(T\) in case the world doesn’t terminate then. But to find a justification for the amount to leave behind at \(T\), DM will need an assessment of the world beyond \(T\). That would, however, amount to including the world beyond \(T\). And so on.