<p>In this paper, we categorize the three positions in Human-Agent Interaction (HAI), which studies the interaction between humans and robots or virtual agents, by positioning existing research based on Gunji’s models of”artificial intelligence, natural intelligence, and natural-born intelligence.” We then introduce the concept of a trilemma among”free will, locality, and determinism” and examine how each position can be described from this perspective. As a result, we present an overview of the current state of HAI research and identify challenges for its future.</p>