An instrumentalist explanation of pragmatic encroachment

Many have found it plausible that practical circumstances can affect whether someone is in a position to know or rationally believe a proposition. For example, whether it is rational for a person to believe that the bank will be open tomorrow can depend not only on the person's evidence but also on how practically important it is for the person not to be wrong about the bank being open tomorrow. This supposed phenomenon is known as "pragmatic encroachment" on knowledge and rational belief. Assuming that the phenomenon is real, I ask what explains it. I argue that a variant of instrumentalism about epistemic reasons offers a natural explanation, that at the same time is able avoid commitment to a more radical form of pragmatism.