“MUST THINKING” is thinking from the outside to the inside. We assume what is inside the box by what is on the outside.
“MAY THINKING is more organic and permits things to occur on their own; be it evolution; wandering along a path; allowing water to trickle in whichever direction it seems to “want to take. It is important to know the grain of the reality before attempting to deal with it.
EXAMPLES of MUST THINKING: He must have been mentally ill and crazy to go on such a shooting spree. She must have known they would be looking for her.
The Reasoning akin to the world of finance: The fastest way to lose weight, in the world of Finance, is to cut off one's leg (“Oh, I did not know you did not want to do that”). In the world of finance, we save by “cutting off whole swaths of departments; eliminating projects, and sometimes we try to make money by buying back our own stock — taking all sorts of radical steps to make the stock "jump" in value. (It's a bit like eating one's foot to gain weight. It is short sighted and purely result oriented without regard to other considerations and tradeoffs.)