Sally Jackson explicates the notion of the “disagreement space” in a new Topoi article:
“a position that remains in doubt remains in need of defense” ((p 12, Sally Jackson. Reason-Giving and the Natural Normativity of Argumentation. Topoi. 2018 Online First. http://doi.org/10.1007/s11245-018-9553-5))
“The most important theoretical consequence of seeing argumentation as a system for management of disagreement is a reversal of perspective on what arguments accomplish. Are arguments the means by which conclusions are built up from established premises? Or are they the means by which participants drill down from disagreements to locate how it is that they and others have arrived at incompatible positions? A view of argumentation as a process of drilling down from disagreements suggests that arguers themselves do not simply point to the reasons they hold for a particular standpoint, but sometimes discover where their own beliefs come from, under questioning by others who do not share their beliefs. A logical analysis of another’s argument nearly always involves first making the argument more explicit, attributing more to the author than was actually said. This is a familiar enough problem for analysts; my point is that it is also a pervasive problem for participants, who may feel intuitively that something is seriously wrong in what someone else has said but need a way to pinpoint exactly what. Getting beliefs externalized is not a precondition for argument, but one of its possible outcomes.” ((p 10, Sally Jackson. Reason-Giving and the Natural Normativity of Argumentation. Topoi. 2018 Online First. http://doi.org/10.1007/s11245-018-9553-5))
From Sally Jackson’s Reason-Giving and the Natural Normativity of Argumentation. ((Sally Jackson. Reason-Giving and the Natural Normativity of Argumentation. Topoi. 2018 Online First. http://doi.org/10.1007/s11245-018-9553-5))
The original treatment of disagreement space is cited to a book chapter revising an ISSA 1992 paper ((Jackson S (1992) “Virtual standpoints” and the pragmatics of conversational argument. In: van Eemeren FH, Grootendorst R, Blair JA, Willard CA (eds) Argument illuminated. International Centre for the Study of Argumentation, Amsterdam, pp. 260–226)), somewhat harder to get one’s hands on.