This paper studies a contract between an optimistic agent and a realistic principal, both risk-neutral. Even with complete contracts and ex-ante symmetric information, it may be impossible to achieve the first-best unless the weight on emotions is sufficiently low.

The so-called "Weitzman-Gollier puzzle" is the fact that two seemingly symmetric and equally plausible ways of dealing with uncertain future discount rates appear to give diametrically opposed results. The puzzle is resolved when agents optimize their consumption plans. The long run discount...