Hypothetical contract you can have stupid contracts that can dictate horrible things, and it is not a tangible object. This contract is hypothetical, and he thinks under these conditions to which this would work, we are perfectly rational, we are perfectly selfish, you are totally ignorant of who you are, you do not know your place in society or your identity. But what you do have is knowledge of stats. about the population, or facts about distribution about different things in society. You can be selfish even if you do not know who you are, you look at the stats. of the population and the chances of who you are.