Abstract“Schools should remain open during the COVID-19 pandemic, because there is no evidence indicating that children can get the virus.” Many European policy-makers have employed such arguments from ignorance to argue for a course of action in a situation in which science lacked vital information. What is particularly challenging about such arguments is that, despite the ignorance involved, they are used to justify policies meant to deal with practical problems. Limited information (‘there is no evidence indicating that children can get the virus’) is used as a basis for decision-making that might have significant consequences for the population (‘schools should remain open’). This chapter explains the intricate but unavoidable relationship between arguments from ignorance and policy-making. Moreover, evaluation criteria are developed to distinguish between reasonable and unreasonable arguments from ignorance in policy-making by taking into consideration the structure of these argument types and their contexts of application. Finally, the chapter assesses two real-life instances of arguments from ignorance employed by the European Commission and the European Center for Disease Prevention and Control during the COVID-19 pandemic. Such an assessment sets important steps in understanding how arguments from ignorance can facilitate or reduce acceptance of the measures proposed by policy-makers.