In philosophy, the original position is a hypothetical position from which members of society would consider which principles they would select for the basic structure of their society if they had no knowledge ahead of time regarding the position which they would end up occupying in that society. The idea of having no such knowledge, because everyone is behind a veil of ignorance, represents a thought experiment often associated with the work of the American philosopher John Rawls.

In this "original position", their position behind the "veil of ignorance" prevents everyone from knowing their ethnicity, social status, gender, and (crucially in Rawls's formulation) their or anyone else's ideas of how to lead a good life. Ideally, this would force participants acting rationally to adopt an "initial agreement" on the principles impartially.

In Rawls's theory the original position plays the same role as the "state of nature" does in the social contract tradition of Thomas Hobbes 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.

Rawls coined the phrases original position and veil of ignorance. However, the same thought experiment had already been described earlier in social choice by William Vickrey and John Harsanyi, who independently derived proofs showing a rational observer in the original position would adopt a utilitarian framework.

The concept of the veil of ignorance has been in use by other names for centuries by philosophers such as John Stuart Mill and Immanuel Kant whose work discussed the concept of the social contract, Adam Smith with his "impartial spectator", or the ideal observer theory. John Harsanyi was the first to mathematically formalize the concept, using it to an argument in favor of utilitarianism rather than an argument for a social contract (as rational agents consider expected outcomes, not worst-case outcomes). The usage of the term by John Rawls was developed in his 1971 book A Theory of Justice.

Modern work tends to focus on the different decision theories that might describe the choice of the decision-maker "behind the veil". In addition, Michael Moehler has shown that, from a moral point of view, decision theory is not necessarily central to veil of ignorance arguments, but the precise moral ideals that are assumed to model the veil. From a moral point of view, there is not one veil of ignorance but many different versions of it.

Rawls specifies that the parties in the original position are concerned only with citizens' share of what he calls primary social goods, which include basic rights as well as economic and social advantages. Rawls also argues that the representatives in the original position would adopt the maximin rule as their principle for evaluating the choices before them. Borrowed from game theory, maximin stands for maximizing the minimum, i.e., making the choice that produces the highest payoff for the least advantaged position. Thus, maximin in the original position represents a formulation of social equality.

The reason that the least well off member gets benefited is that it is argued that under the veil of ignorance people will act as if they were risk-averse. The original position is a unique and irrevocable choice about all the most important social goods, and they do not know the probability they will become any particular member of society. As insurance against the worst possible outcome, they will pick rules that maximize the benefits given to the minimum outcome (maximin).