  The first step is now familiar: To act is to do or choose something for a reason. The second step is based on Korsgaard’s idea that we have reasons to act because of our practical identities (such as one’s identity as a father, or lecturer, or Englishman), not because acts have reasons attached to them in themselves. Once again, realists might demur, claiming that some actions are rational things to do, because some things have value as such: so, perhaps knowledge is valuable in itself, thereby making it rational to seek it. But let us leave such worries aside and assume with Korsgaard that nothing is objectively rational for us to do.