You can imagine a two states world (it rains, it shines), or an 11 states world(the sum of two dices come up anything from 2-12)or an almost unimaginably large state space in space which actually live Then the utility function can be thought of as being defined over states of the world u(c1, c2,.cs) Where cs is consumption in state s In fact- this is the most important point-if you define all forms of consumption as state contingent consumption-good x in state s, then the mwg discussion in chapters 1-3 can handle uncertainty with no changes whatsoeverYou can imagine a two states world (it rains, it shines), or an 11 states world (the sum of two dices come up anything from 2-12) or an almost unimaginably large state space in space which actually live. Then the utility function can be thought of as being defined over states of the world: uc1, c2,.. cS where cs is consumption in state s. In fact– this is the most important point– if you define all forms of consumption as "state contingent consumption" – good x in state s, then the MWG discussion in chapters 1-3 can handle uncertainty with no changes whatsoever