The Washout Argument against Longtermism

Abstract We cannot justifably believe that any currently available actions will have a non-negligible positive influence a billion or more years in the future. I offer three arguments for this thesis. According to the Infinite Washout Argument, given the non-zero chance that your actions will produce infinitely many effects, any finite effects will wash out in expectation. According to the Cluelessness Argument, we cannot justifiably guess what actions are likely to have positive effects in a billion-plus years. We cannot be justified, for example, in thinking that nuclear war or human extinction would be more likely to have bad than good consequences that far into the future. According to the Negligibility Argument, even if we could justifiably guess that some particular action is likelier to have good than bad consequences that far in the future, the odds of good consequences would be negligible due to the compounding of probabilities over time.