 Lederman (2018b) generalizes the argument to arbitrary cases and sources of public information, to conclude that people never achieve common knowledge or belief. In his view, the unattainability of common knowledge is not a concern in terms of a possible loss of explanatory power for social behavior. While common knowledge and public information from which it proceeds have long been considered crucial for coordinating behavior, Lederman claims that in fact coordination requires neither (see the discussion of Lederman 2018a in the next section.) Against Lederman, Immerman (2021) argues that the skeptical argument sketched here fails in a large set of circumstances, and hence fails to prove the unattainability of common knowledge. The key idea in Immerman’s attempt to refute Lederman’s argument is that there are many perceptual values that agents will not entertain to begin with, as if, in the original sailboat example, they knew that all masts within 100 and 300 cm tall had been stolen. According to Immerman, cases of such “knowledge of gaps” are not at all uncommon and their availability prevents Lederman’s argument to go through.