This paper presents an adaptive approach to deal with the problem of integrating several heterogeneous reasoning methods (RMs) in a single system. It's based on three observations: (1) several RMs may be usable for solving the same problem, (2) there is no deterministic way to find the most adequate (RM) and (3) there no deterministic way to combine the RMs. Some heuristics can guide the problem-solving process in combining the RMs and if necessary, switching from one RM to another according to the context. The real problem is that the context depends on dynamic and unpredictable knowledge. An adaptive approach is implemented in a multi-agent system (MAS). The ways to combine the RMs are decided in a decentralized way according to cooperative knowledge embedded in the agents. A dynamic organization is possible thanks to a particular agent role: pivotal.