Abstract
This article puts forth a hypothesis of stages of acquiring physical rules by a robot, and describes issues to develop the robotic program. The first stage is a learning stage without words, and the second stage is a learning stage with words. The second stage has two sub stages; in the first sub stage, the robotic program does not write or read words, and in the second sub stage, the program writes and reads words. Issues to be raised include how to extract physical rules out of continuous flow of sensory and motor inputs, how to construct hierarchical structures of physical rules (or causes and effects) out of continuous flow of the inputs, and what assumptions can be made for trying to construct a robot that acquires physical rules.