Glossarytaught in M6.05, M9.04
Pre-mortem
Also called premortem, prospective hindsight.
Imagining, before committing, that the decision has failed badly, and writing down why.
It works because it changes the question from whether this could go wrong, which invites a defensive answer, to why it did go wrong, which invites specifics.
Applied to an investment it produces a list of the two or three things that would actually destroy the thesis, which is also the monitoring list for the position.
It takes fifteen minutes before you commit, and more often than not it changes the position size.