“Only an unsatisfied preference is bad. In other words, he argues that although it is good to have fulfilled whatever desires one might have, one is not better off having a fulfilled desire than having no desire at all. By way of example, consider the case in which we ‘paint the tree nearest to Sydney Opera house red and give Kate a pill that makes her wish that the tree nearest to Sydney Opera House were red’*. Professor Fehige plausibly denies that we do Kate any favour in doing this. She is no better off than had we done nothing. What matters is not that people have satisfied desires but that they do not have unsatisfied ones. It is the avoidance of frustration that is important.

* Fehige, Christoph, ‘A Pareto Principle for Possible People’, 513–14.”