It is increasingly argued that there is a single unified constitutive norm of both assertion and practical reasoning. The most common suggestion is that knowledge is this norm. If this is correct, then we would expect that a diagnosis of problematic assertions should manifest as problematic reasons for acting. Jennifer Lackey has recently argued that assertions epistemically grounded in isolated second-hand knowledge (ISHK) are unwarranted. I argue that decisions epistemically grounded in premises based on ISHK also seem inappropriate. I finish (...) by suggesting that this finding has important implications for the debates regarding the norms of assertion and practical reasoning. (shrink)