I have heard that SICP calls it 'design by wishful thinking'[1]. In planning, it's called "planning for the unexpected", and can be seen i.e. in "built-in snow

I have heard that SICP calls it 'design by wishful thinking'[1]. In planning, it's called "planning for the unexpected", and can be seen i.e. in "built-in snow days" in primary school calendars [2]. Mathematicians will sometimes insert a new variable where necessary in an equation, then go back and figure out what the math should have been to make that variable work. In physics, the neutrino was something we knew must exist but didn't know what it was, so we made a placeholder [3]. I think of it as an allegory: Our forward progress is like running up a set of stairs. Yet the stairs are only half completed. Our goal is to have our foot moving downward before the stair is placed, with the confidence (or faith) that others will place and secure each stair before our foot hits it. [1] https://news.ycombinator.com/item?id=5765447 https://news.ycombinator.com/item?id=5765447 [2] Example: http://bdtonline.com/local/x2056602588/Mercer-school-system-marks-all-built-in-snow-days-off-its-calendar http://bdtonline.com/local/x2056602588/Mercer-school-system-... [3] http://www.ps.uci.edu/~superk/neutrino.html http://www.ps.uci.edu/~superk/neutrino.html