Ranking Multidimensional Alternatives and Uncertain Prospects

We introduce a ranking of multidimensional alternatives, including un- certain prospects as a particular case, when these objects can be given a matrix form. This ranking is separable in terms of rows and columns, and continuous and monotonic in the basic quantities. Owing to the theory of additive separability developed here, we derive very precise numerical representations over a large class of domains (i.e., typically not of the Cartesian product form). We apply these representation to (1) streams of commodity baskets through time, (2) uncertain social prospects, (3) un- certain individual prospects. Concerning (1), we propose a finite horizon variant of Koopmans's (1960) axiomatization of infinite discounted util- ity sums. The main results concern (2). We push the classic comparison between the ex ante and ex post social welfare criteria one step further by avoiding any expected utility assumptions, and as a consequence ob- tain what appears to be the strongest existing form of Harsanyi's (1955) Aggregation Theorem. Concerning (3), we derive a subjective probability for Anscombe and Aumann's (1963) finite case by merely assuming that there are two epistemically independent sources of uncertainty. characteristics.