Plotinus argues that materialism cannot explain reflexive cognition. He argues that mere bodies cannot engage in the self-reflexive activity of both cognizing some content and being cognitively aware of cognizing this content. Short of outright denying the cognitive unity underlying this phenomenon of self-awareness, materialism is in trouble. However, Plotinus bases his argument on the condition that material bodies are capable of a spatial unity at most, and while this condition has purchase on ancient materialists, it would be rejected today. (...) After considering objections based on our contemporary understanding of a material body, I amend Plotinus' argument to focus instead on the core materialist commitment to external efficient-causal relations. This amended argument regains its urgency for materialism, while retaining the spirit of Plotinus' view. (shrink)