Abstract: When a person has evidence about their capacity to assess the evidence for or against a proposition, for example, when they have evidence that their assessment is subject to bias, they have higher-order evidence. A popular view in epistemology is that higher-order evidence can make a difference to whether it is rational for a person to believe a proposition. In particular, many think that there are cases in which it would be rational to believe a proposition in the absence of higher-order evidence but not rational to believe that same proposition in the presence of higher-order evidence. In this paper, I will ask, how? How might higher-order evidence have this effect? I will outline three answers to this question and show that they fail. In closing, I will query the motivation for thinking that higher-order evidence makes a rational difference.