In the original position, one is asked to consider which principles they would select for the basic structure of society, but they must select as if they had no knowledge ahead of time what position they would end up having in that society. This choice is made from behind a “veil of ignorance”, which prevents them from knowing their ethnicity, social status, gender and, crucially in Rawls’s formulation, their or anyone else’s idea of how to lead a good life. Ideally, this would force participants to select principles impartially and rationally.

https://en.m.wikipedia.org/wiki/Original_position