People are taught to trace how they move from observable data to action: selecting some data from what a camera would record, adding meaning, making assumptions, drawing conclusions and forming beliefs that drive action, with beliefs in turn steering which data are selected next, a reinforcing loop that can narrow attention to data that confirm existing beliefs. When people disagree about a conclusion, Argyris's remedy is to make explicit the data each selected and the inferential steps taken, and to understand the other person's ladder.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.