Explaining risky choices without assuming preferences

Economic theories of choice under uncertainty assume that agents act as if they have preferences which govern their choices between risky options. Theories differ as to the exact specification of the preference structure, but it is common to assume that preferences are complete and satisfy certain consistency requirements such as transitivity and monotonicity. In this paper, it is argued that there may be reason to doubt whether individuals act as if they have complete and consistent preferences over risky actions. Instead it is suggested that individuals should be thought of as actively constructing preferences through a process which I call ''rationalisation''. It is then argued that rationalisation provides a basis for understanding certain experimentally observed ''anomalies'' which appear quite at odds with conventional theory.