Fredkin's paradox concerns the negative correlation between the difference between two options and the difficulty of deciding between them. Developed further, the paradox constitutes a major challenge to the possibility of pure instrumental rationality.
Proposed by Edward Fredkin, it reads: "The more equally attractive two alternatives seem, the harder it can be to choose between them—no matter that, to the same degree, the choice can only matter less." Thus, a decision-making agent might spend the most time on the least important decisions.
An intuitive response to Fredkin's paradox is to calibrate decision-making time with the importance of the decision: to calculate the cost of optimizing into the optimization. However, this response is self-referential and spawns a new, recursive paradox: the decision-maker must now optimize the optimization of the optimization, and so on.