If somebody prefers an income distribution more favorable to the poor for the sole reason that he is poor himself, this can hardly be considered as a… - John Harsanyi

We can regard the vector c_i as representing certain physical, social, and psychological attributes of player i himself in that it summarizes some crucial parameters of player i's own payoff function U_i as well as the main parameters of his beliefs about his social and physical environment... the rules of the game as such allow any given player i to belong to any one of a number of possible types, corresponding to the alternative values of his attribute vector c i could take... Each player is assumed to know his own actual type but to be in general ignorant about the other players' actual types.

My interest in game-theoretic problems in a narrower sense was first aroused by John Nash's four brilliant papers, published in the period 1950-53, on cooperative and on noncooperative games, on two-person bargaining games and on mutually optimal threat strategies in such games, and on what we now call Nash equilibria.

Now a value judgment on the distribution of income would show the required impersonality to the highest degree if the person who made this judgment had to choose a particular income distribution in complete ignorance of what his own relative position... would be within the system chosen. This would be the case if he had exactly the same chance of obtaining the first position (corresponding to the highest income) or the second or the third, etc. up to the last position (corresponding to the lowest income) available within that scheme.