Rationalizability by a weak order is perhaps the fundamental property of concern in rational choice theory. On the domain of all finite menus, it admits a characterization by a very simple, apparently novel axiom of atypical form. The axiom makes clear how weak order rationalizability strengthens Path Independence. On arbitrary domains, it is strictly weaker than many standard conditions that are equivalent to weak order rationalizability on the full domain. Simple domain conditions restore equivalence with the conjunction of Sen’s Properties α and β and with weak order rationalizability.
We study different notions of consistency in a model of preference aggregation where the feasible set of alternatives may vary. We show that there exists no social choice function (SCF) satisfying contraction consistency (CC), non-dictatorship, and Pareto efficiency (PE). We then characterize a class of priority-based SCFs, called Priority Rules (PRs), in two ways: first, using PE and efficient dominance, a WARP-type consistency condition with respect to PE; and second, using PE, weak contraction consistency, and invariant efficiency. We also characterize Decisive Individual Rules, in which the decisive individual may vary across profiles, using a top-selection condition, a weakening of CC, and an intersection condition on decisive individuals. Finally, in the social choice correspondence (SCC) setting, when the number of alternatives exceeds the number of voters, we characterize Voting by Minimal Committees SCCs using correspondence contraction consistency, top selection, unanimity, and committee intersection.
Several economically relevant events, such as policy interventions or nominal adjustments, occur at irregular intervals. This paper extends the martingale difference reduction technique to multivariate rational expectations (RE) models on non-periodic time domains. We establish an invariance property showing that, under constant parameters, the recursive solution structure depends on the ordering of events rather than their calendar spacing. Standard likelihood-based estimation therefore applies without modification to irregularly timed observations. We also characterize equilibrium multiplicity by distinguishing components associated with arbitrary initial conditions and non-fundamental forecast errors. Monte Carlo evidence illustrates these results and shows that interpolation onto a regular grid can introduce substantial bias and distort inference.
We consider a large population aggregative game with strategic complementarities. The game has multiple Nash equilibria, which can be Pareto ranked. We apply the k−sampling best response dynamic to this game. This dynamic is generated when agents best respond to the strategies of k randomly sampled opponents. We establish conditions under which the Pareto efficient equilibrium is almost globally asymptotically stable under this dynamic. Results depend upon the relationship between benefits and costs in the game and the sample size.
Decisions to pursue higher education are shaped by economic incentives, peer effects, and expectations about future returns. This paper develops a non-linear dynamic model of educational participation for study fields in which the motivations to enrol are heterogeneous and cannot be reduced to a single driver. Agents allocate resources between education and consumption while their preferences evolve endogenously. Followers are reinforced by aggregate participation, while Positional Agents respond to social distinctiveness and to an endogenous wage premium that declines with the supply of educated workers. We show that the interaction between imitation, positional concerns, and labour-market feedback can generate endogenous cycles and irregular dynamics, especially for intermediate mixtures of behavioural types. Allowing population shares to evolve adds a further source of instability through switching between behavioural rules. Finally, policy interventions are not necessarily stabilizing: counter-cyclical cost subsidies may discipline enrolment, whereas strong behavioural signalling can amplify imitative responses and generate overreaction.
