@Christian_BB responded to my post Does Rigour Matter? with a comment "Rigour matters when building. It matters less when trying to get people converging." I replied, "Rigour matters when building consensus. Unless you just want people to have a warm feeling of convergence."
Roughly speaking, there are three modes of convergence and consensus.
1. Symbolic. We have a formal agreement, and maybe set up some formal structures that perpetuate this agreement, but there is enough loophole and exception and wriggle-room that we don't need take it seriously.
2. Imaginary. We have a warm impression that we are all in agreement about something, and a vague hope that all the details will sort themselves out somehow.
3. Real. We have a tough negotiation around the details, and acknowledge the practical trade-offs and compromises that are required to implement the agreement.
Christian may be perfectly correct that a warm feeling (imaginary convergence) may be a useful and motivating step towards real convergence. But I have seen the converse too many times - when a meeting or workshop evades or fudges the details of some plan, leaves the details to be sorted out later, and then fails to follow through. This is a common feature of Management-by-Powerpoint, as notoriously practised by the Pentagon before the US invasion of Iraq.
And where there is a lot of mutual hostility and mistrust, it is probably unrealistic to expect warm feelings to emerge until long after a real agreement has been forged and implemented.
So an imaginary agreement is neither necessary not sufficient as a precondition for a real agreement.