In this paper I aim to examine some problematic implications of the fact that individuals are prone to making systematic reasoning errors, for resource egalitarianism. I begin by disentangling the concepts of preferences, choices and ambitions, which are sometimes used interchangeably by egalitarians. Subsequently, I claim that the most plausible interpretation of resource egalitarianism takes preferences, not choices, as the site of responsibility. This distinction is salient, since preference-sensitive resource egalitarianism is faced with an important objection when applied to situations (...) in which the empirically reasonable assumption that individuals have different degrees of computational abilities is introduced. I first show that this objection can be raised in cases involving individuals who have incomplete information, but that it ultimately fails for such cases since we can appeal to higher order insurance markets in order to mitigate any initial concerns. I further claim, however, that the objection is much more powerful in cases involving individuals who have different reasoning skills, since the appeal to higher order insurance markets is no longer tenable. Consequently, the ideal principle of justice proposed by Dworkin is met with a new feasibility challenge. Finally, I claim that the problem of reasoning errors and various forms of cognitive biases also affect Dworkin’s non-ideal principle of justice, skewing the outputs of the hypothetical insurance mechanism in an unjustifiable manner. (shrink)