Normative political theorists frequently compare hypothetical scenarios for the purpose of identifying reasons to prefer one kind of institution to alternatives. We examine three types of "unfair" comparisons and the reasoning errors associated with each. A theorist makes an _obscure comparison_ when one (or more) of the alternatives under consideration is underspecified; a theorist makes a _mismatched comparison_ when they fail to hold fixed the relevant contextual factors while comparing alternatives; and a theorist makes an _irrelevant comparison_ when they compare (...) alternatives assuming contextual factors that differ in important respects from those they "should" assume given their theoretical aims. We then introduce the notion of a modeling mindset and show how this mindset can help theorists detect and avoid the three types of error. We conclude with a reconstruction of Cohen's (2009) camping trip thought experiment to illustrate the approach. (shrink)