This paper aims to show that the Knowledge Norm of Assertion (KNA) can lead to trouble in certain dialectical contexts. Suppose a person knows that p but does not know that they know that p. They assert p in compliance with the KNA. Their interlocutor responds: ‘but do you know that p?’ It will be shown that the KNA blocks the original asserter from providing any good response to this perfectly natural follow‐up question, effectively forcing them to retract p from the conversational scoreboard. This finding is not simply of theoretical interest: I will argue that the KNA would allow the retort ‘but do you know that p?’ to be weaponized in strategic communication, serving as a tool for silencing speakers without having to challenge their testimonial contributions on their own merits. Our analysis can thereby provide a new dimension to the study of epistemic injustice, as well as underscoring the importance of considering the norms governing speech acts also from the point of view of non‐ideal social contexts.