Abstract So far the book has worked on the assumption that the confrontation with contrary evidence always requires rational believers to reduce their credence in the relevant propositions. This chapter introduces the notion of “evidential preemption,” which occurs when a testifier, in addition to offering testimony that p, also warns the hearer that others will try to persuade them of contrary views. This chapter argues that whenever it is rational for someone to accept the “ground-level” testimony on offer, it is also rational for them to accept the warning about what others will tell them. When they are subsequently confronted with this testimony, its evidential force has effectively been neutralized, since it is, essentially, information the subject has already conditionalized on. In this way, evidential preemption can serve as a tool for “epistemic inoculation,” all but ensuring that subjects cannot make beneficial use of the contrary evidence to correct their beliefs.