In this paper we describe a logic-based AI architecture based on Brooks' Subsumption Architecture. We axiomatize each of the layers of control in his system separately and use independent theorem provers to derive each layer's output actions given its inputs. We implement the subsumption of lower layers by higher layers using circumscription. We give formal semantics to our approach. 1 Introduction In [?], Brooks proposed a reactive architecture embodying an approach to robot control different on various counts from traditional approaches. He decomposed the problem into layers corresponding to levels of behavior, rather than according to a sequential, functional form. Within this setting he introduced the idea of subsumption, that is, that more complex layers could not only depend on lower, more reactive layers, but could also influence their behavior. The resulting architecture was one that could service simultaneously multiple, potentially conflicting goals in a reactive fashi..