Editing Soft systems methodology (section)

=== Two streams (1988) ===
The two-stream model of SSM recognizes the crucially important role of history in human affairs, and for a given group of people their history determines what will be noticed as significant and how it will be judged. This expression of SSM is presented as an approach embodying not only a logic-based stream of analysis (via activity models) but also a cultural and political stream which enable judgements to be made about the accommodations between conflicting interests which might be reachable by the people concerned and which would enable action to be taken.

This particular expression of SSM removes the dividing line between the world of the problem situation and the systems thinking world.<ref name="ChecklandScholes1999" />