I'm not sure if this is the same thing or not, but thought I would throw it in anyway, in case it sparks something else off.

From Wikipedia:
A set of considerations which hold good only because of a completed process, is read into the content of the process which conditions this completed result. A state of things characterizing an outcome is regarded as a true description of the events which led up to this outcome; when, as a matter of fact, if this outcome had already been in existence, there would have been no necessity for the process