Knowledge Bridge

Knowledge bridges do two jobs at once and the pairing is the point. They carry expertise outward into terms a novice can use, and they collectively audit what the epistemic community is doing, so the same people who translate also check. Separating those two functions would produce either translators who cannot evaluate or auditors nobody can understand, and the bridge exists because expertise reaching a population without being auditable by it is exactly the problem the whole design is trying to avoid. The demagogue is the named danger. Someone with the ability and time to develop mass appeal but who is not the source of expertise will otherwise occupy the space between the experts and everyone else, which is a position of enormous power precisely because it is uncheckable from either side. Bridges close that gap by making the route continuous. Knowledge bridges allow discussion to be held at every level of expertise and corrected by those with greater knowledge, so there is no rung at which a person can stand and interpret freely. The traffic runs both ways, which is the last sentence of the definition and the part that keeps the arrangement from being a broadcast. Anyone in the user group can promote ideas upward and can achieve elite expertise if they wish, so the bridge is a path rather than a channel and the epistemic community stays permeable.

Science communication and public understanding of science address the same territory, with the deficit model long criticized for treating the public as empty vessels and later approaches emphasizing dialogue. Knowledge brokering is an established term in policy and health research for intermediaries between evidence and practice, and boundary spanning describes similar roles in organizations. What distinguishes Marsh's version is the auditing function. Science communicators explain and knowledge brokers translate, but neither is charged with collectively checking the community whose work they carry, which in her design is what stops the epistemic community becoming an oligarchy rather than a resource.