The non-identity problem, which is much discussed in bioethics, metaphysics and environmental ethics, is usually examined by philosophers because of the difficulties it raises for our understanding of possible harms done to present human agents. In this article, instead of attempting to solve the non-identical problem, I explore an entirely different feature of the problem, namely the implications it has for the admissibility of outlandish or bizarre thought experiments. I argue that in order to sustain the claim that later born selves cannot be harmed (since they are in fact different persons), one must rule inadmissible certain kinds of modally bizarre imaginary cases. In this paper I explore how one might justify such a constraint on outlandish cases and, in so doing, develop the outline of a model for distinguishing between admissible and inadmissible imaginary cases in philosophical debate
