> Because we don't know how well COVID-19 vaccines keep people from spreading the disease. There are lots of things we don’t know. We don’t know if a supervolc

> Because we don't know how well COVID-19 vaccines keep people from spreading the disease. There are lots of things we don’t know. We don’t know if a supervolcano will blow next month and send the planet into a multi-year winter. Should we change our behavior today so that if that happens next month lives will be saved? We don’t know and therefore we should do something is assuming the conclusion.