ABSTRACT
This chapter discusses the important trade-offs and the implications for communicative planning. The theorems of social choice and incentive theory shed light on major hindrances on the road to Habermasian dialogue. The economics of planning has long been concerned with how decentralized information can be acquired by a planning agency from subordinates whose welfare is affected by what they communicate. The analytic tools are several impossibility theorems from social choice theory and the economic theory of incentives proving the difficulties of combining dialogue and democracy with consistency and efficiency. The conditions of strategy-proofness, Pareto efficiency, and individual rationality are only necessary for a well-working economic system; they are also required to achieve dialogue and thus the ideal of deliberative democracy. On the contrary, planners show that the resolution of important planning problems depends on planners that are willing to approach dialogue or enter similar planning processes based on empathy and altruism.
