Research seminar with Michael Otsuka, Professor of Philosophy, London School of Economics. Full title: How to pool risks across generations: A reciprocity-based case for an unfunded pay as you go (PAYG) pension This seminar was arranged by the Institute for Futures Studies and the Center for Population-Level Bioethics at Rutgers University, New Jersey, USA. Abstract In a 'pay as you go' (PAYG) pension scheme, money is directly transferred from those who are currently working to pay the pensions of those who are currently retired. Rather than drawing from a pension fund consisting of a portfolio of financial assets, these pensions are paid out of the state treasury's coffers. The pension one is entitled to in retirement is often, however, a function of, even though not funded by, the pensions contributions one has made during one’s working life. In this seminar, I explore the extent to which a PAYG pension can be justified as a form of indirect reciprocity that cascades down generations. This contrasts with a redistributive concern to mitigate the inequality between those who are young, healthy, able-bodied, and productive and those who are elderly, infirm, and out of work. I explore claims inspired by Ken Binmore and Joseph Heath that PAYG pensions in which each generation pays the pensions of the previous generation can be justified as in mutually advantageous Nash equilibrium. Recorded at the Institute for Futures Studies on March 9, 2022.