What the move is
Holding two at once means running two ways of thinking on the same situation, properly and at the same time, and then comparing what they found. Switching tries four frames for a few minutes each and keeps one. Holding two gives two frames twenty-five minutes each and keeps both, to see where they part company.
The output is a map of the decision’s weak points: the claims both frames support, which you can treat as sound, and the places they split, which become questions to investigate. No decision is taken yet.
The idea behind it
Roger Martin studied leaders who were good at hard decisions and found that many of them could hold two opposed models in mind without rushing to pick one. He called it integrative thinking. The tension between the models was the useful part, because it showed where each was missing something.
Michael Jackson, and Mingers and Brocklesby, make the same case for analysis. Any single method sees part of a situation. Two methods chosen to differ catch each other’s errors, and agreement between them means more than either alone.
Why it works
A neat analysis from one frame hides its own assumptions. Put it beside an analysis from another frame and the assumptions show up as points of disagreement, which are far easier to see than an assumption on its own.
Choose the pair with care. Frames on opposite diagonals of the matrix, such as systems and computational or design and critical, disagree about almost everything, which can swamp a first attempt. Neighbours, such as systems and design, share a concern with wholes and disagree more narrowly, so the splits are easier to pin down.