Thought bubble

Two closure mechanisms are named and they are different in kind. Forum means the venue itself excludes outside thought, which is a structural closure achieved by where the conversation happens and who can reach it. Propaganda means the material circulating inside does the excluding, which is a closure achieved by what the participants are supplied with. Either produces the same result, and the second sentence identifies what that result is. A thought bubble is an endogroup with a strong endoreality, so nothing new is being described and the term names a particular intensity of something the framework already covers. Strength of endoreality has consequences Marsh sets out elsewhere. A public unable to think of a principle without aligning it to an endo-ideal or negative image is a public trapped in a strong endoreality, and the out-of-touch tendencies of an endo-ideal follow from the strength of the reality they live inside. The endofilter does the work at the level of the individual, filtering all information from universal reality according to the laws of endoreality. Her observations about platforms are the contemporary application. Recommendation algorithms were once notable for the blatant grooming of audiences towards misogyny and other extremist violence, and this is now a feature of most large platforms, which is the forum mechanism and the propaganda mechanism operating together.

Echo chamber and filter bubble are the established terms, the first from Cass Sunstein's work on group polarization and the second from Eli Pariser's on algorithmic personalization, and empirical research has complicated both, finding that heavy internet users often encounter more diverse sources rather than fewer. Groupthink, from Irving Janis, describes closure in small decision-making groups. Marsh's version differs by making the closure a property of an endogroup rather than of an information environment, which means the bubble persists across venues and is not fixed by exposure to other views, since the endofilter processes them on arrival.