The original position (OP), often referred to as the veil of ignorance, is a thought experiment used for reasoning about the principles that should structure a society based on solidarity. The phrases original position and veil of ignorance were coined by the American philosopher John Rawls, but the thought experiment itself was developed by William Vickrey and John Harsanyi in earlier writings.
In the original position, you are asked to consider which principles you would select for the basic structure of society, but you must select as if you had no knowledge ahead of time what position you would end up having in that society. This choice is made from behind a "veil of ignorance", which prevents you from knowing your ethnicity, social status, gender and, crucially in Rawls' formulation, your or anyone else's idea of how to lead a good life. Ideally, this would force participants to select principles impartially and rationally.
In Rawls's theory the original position plays the same role that the "state of nature" does in the social contract tradition of Thomas Hobbes, Jean-Jacques Rousseau, and John Locke. The original position figures prominently in Rawls's 1971 book, A Theory of Justice. It has influenced a variety of thinkers from a broad spectrum of philosophical orientations.