The Economics of Optimism and Pessimism

SUMMARY This paper suggests a way of incorporating the important concepts of optimism and pessimism into the accepted model of decision‐making under uncertainty. We exploit the primitive notion that an optimist is someone who over‐estimates (underestimates) the likelihood of favourable (unfavourable) outcomes. We show that this incorporation enables us to explain several commonly observed apparent violations of Subjective Expected Utility Theory. Several illustrations and economic applications are presented, and we show that attitude to ‘fate’ (as evidenced in optimism and pessimism) is a different dimension of personality than attitude to risk. We conclude by relating our extension of SEU theory to other recent extensions.