In consensus building process in medicine, it is crucial for its participants to understand why each of the stakeholders has his/her opinion. The aim of this paper is to develop the notion of "reason of opinion" and to propose the idea of "history of reason" to understand what a satisfactory consensus is in conflict resolution in medicine. The notion and the idea contain four factors, that is, 1) when one started to form the reason of an opinion, 2) how one formed the reason, 3) what the relationship between the present opinion and its reason is, and 4) what kind of result is supposed to come out after the decision. Knowing the stakeholder's history of reason makes it possible 1) for stakeholders to understand more deeply the patient's needs and to find the better solution for the situation, 2) for the patient to become aware of his/her own sense of value and to confirm what he/she expects after the decision, 3) for all the stakeholders to decrease the risk of misunderstanding and to share their expectations, 4) and for them to find the way to the final solution. This new approach, which includes the notions of the history of reason and the expectation in stakeholders, leads to the way to integrate both the evidence based medicine and the narrative based medicine.
