Cognitive research questions to clarify possibilities to realize a pedagogical machine were discussed in the paper by Hiraki. To define “teaching-learning behavior, he added three conditions of “learning” to the three conditions of “teaching” by Caro & Hauser. Based on the definition, he discussed about the future research direction of the pedagogical machine. The paper is very stimulative and important to open the discussion of the pedagogical machine. Three questions related to his paper are discussed in this comment:
1) whether the behavior of “teaching-learning” is fully reduced to the interaction between two individuals,
2) the difficulties for a naive learner to express what are learned along the learning process,
3) whether a human being has the necessary and sufficient skill as a pedagogicalagent.
