How to balance evidence and democracy?

The panel 2 of the ICML 9|CRICS 7 shows that decisions related to health, involve and affect individuals, communities and societies. Scientific knowledge is an accumulative process that evolves continuously bringing evidences to support decision making process. Is there a contradiction between evidence-based policies and public participation in the decision making process? How to balance the use of the scientific evidence with the active participation of individuals, communities and societies?