Abstract
Psychological egoism is the doctrine that all of our actions are ultimately motivated by self-interest, even including seemingly altruistic actions. Although this view is commonly referred to as \vacuous" or \trivially true" because of its immunity to counterexamples, I argue that there are possible observations that can refute this thesis. I describe the experiments, identify the results that could in principle falsify the strongest possible version of psychological egoism and formulate a probabilistic argument against this view. Ultimately, I conclude that a \trivially true" formulation of psychological egoism is an empirical theory that is in all likelihood false.