Immigration rights literature is littered with thought experiments, offering us an up-close view of their use, cogency, and occasional failure. By methodically contrasting well-received thought experiments with controversial ones, we can discover what makes them effective instruments of persuasion and why they are sometimes found wanting. This paper argues that even if a thought experiment avoids undue bias, ambiguity, and other pitfalls of figurative language, it will be unpersuasive if it asks the reader to accept controversial premises. To illustrate, I examine thought experiments including Judith Jarvis Thompson’s “Violinist”, Peter Singer’s “Drowning Child”, and Michael Huemer’s “Marketplace” defending the right to immigrate. The first two examples and others like them are popular, I contend, because they (mostly) avoid asking us to accept iffy postulates. In contrast, thought experiments like Huemer’s are unpersuasive because they adopt premises the uncommitted reader finds implausible.