How vague can one be? Rational preferences without completeness or transitivity

What can it mean for preferences to be rational when transitivity or completenss are not assumed? In this paper we provide a framework and a set of conditions to deal with this question. We provide representation results in terms of a pair of functions, a utility function and a vagueness function.incomplete preferences, vagueness, sure-thing principle

Choice by Lexicographic Semiorders

We propose an extension of Tversky's lexicographic semiorder to a model of boundedly rational choice. We explore the connection with sequential rationalisability of choice, and we provide axiomatic characterisations of both models in terms of observable choice data.lexicographic semiorders, bounded rationality, revealed preference, choice

Choice by lexicographic semiorders

In Tversky's (1969) model of a lexicographic semiorder, preference is generated by the sequential application of numerical criteria, by declaring an alternative x better than an alternative y if the first criterion that distinguishes between x and y ranks x higher than y by an amount exceeding a fixed threshold. We generalize this idea to a fully-fledged model of boundedly rational choice. We explore the connection with sequential rationalizability of choice (Apesteguia and Ballester 2009, Manzini and Mariotti 2007), and we provide axiomatic characterizations of both models in terms of observable choice data.Lexicographic semiorders, bounded rationality, revealed preference, choice

A Theory of Vague Expected Utility

We propose a new theory of choice between lotteries, which combines an 'economic’ view of decision making - based on a rational, though incomplete, ordering - with a 'psychological’ view - based on heuristics. This theory can explain observed violations of EU theory, namely all cyclical patterns of choice as well as violations of independence.incomplete preference relation; cyclical preferences; expected utility

Alliances and Negotiations

A characteristic of many bargaining situations is that the negotiators represents the interests of a set of parties (trade unions, political parties, etc.) with composite interests, whose bargaining behaviour is regulated by some collective decision mechanism. In this paper we provide a natural model of such circumstances, and show how different preference aggregation procedures within the composite player affect the bargaining outcome. In particular we find that unanimity procedures lead to `more aggressive' behaviour than majority procedures, and that procedures which introduce minimum safeguards for the members of an alliance may result in agreements that are worse than without those safeguards.Alliances, Multiperson bargaining

Two-stage Boundedly Rational Choice Procedures: Theory and Experimental Evidence

We study and test a class of boundedly rational models of decision making which rely on sequential eliminative heuristics. We formalize two sequential decision procedures, both inspired by plausible models popular among several psychologists and marketing scientists. However we follow a standard `revealed preference' economic approach by fully characterizing these procedures by few, simple and testable conditions on observed choice. Then we test the models (as well as the standard utility maximization model) with experimental data. We find that the large majority of individuals behave in a way consistent with one of our procedures, and inconsistent with the utility maximization model.Bounded rationality, Choice experiments

Shortlisting

We study the properties of decisions made by committees who select alternatives by constructing shortlists. We find that even when committees are themselves rational, such procedures may not give rise to rational choices. A necessary condition for this to occur is disagreement between committees. However, we delimit substantially the extent of `irrationality' that these procedures allow.Committees, shortlist, menu-dependence, cycles of choice

Moody Choice

If choices depend on the decision maker's mood, is the attempt to derive any consistency in choice doomed? In this paper we argue that, even with full unpredictability of mood, the way choices from a menu relate to choices from another menu exhibits some structure. We present two alternative models of 'moody choice' and show that, in either of them, not all choice patterns are possible. Indeed, we characterise both models in terms of consistency requirements of the observed choice data.bounded rationality, procedural rationality, utility maximization, choice behavior

Consumer Choice and Revealed Bounded Rationality

We study two boundedly rational procedures in consumer behavior. We show that these procedures can be detected by conditions on observable demand data of the same type as standard revealed preference axioms. This provides the basis for a non-parametric analysis of boundedly rational consumer behavior mirroring the classical one for utility maximization.Bounded rationality, Revealed preference, Consumer choice

Alliances and Negotiations

A characteristic of many bargaining situations is that the negotiators represents the interests of a set of parties (trade unions, political parties, etc.) with composite interests, whose bargaining behaviour is regulated by some collective decision mechanism. In this paper we provide a natural model of such circumstances, and show how different preference aggregation procedures within the composite player affect the bargaining outcome. In particular we find that unanimity procedures lead to 'more aggressive' behaviour than majority procedures, and that procedures which introduce minimum safeguards for the members of an alliance may result in agreements that are worse than without those safeguards.Alliances, multiperson bargaining