Agent-based simulation has long been used to study the dynamics of innovation adoption and diffusion. However, the vast majority of these works are limited to an abstract and simplified representation of this process, which does not make it possible to explain the reasons for an agent's change of opinion, an element that is nonetheless fundamental to understanding the dynamics of innovation diffusion. In order to overcome this limitation, we propose an agent-based model of innovation adoption and diffusion based on a classical theory of psychology, the theory of planned behaviour, and on formal argumentation. Each agent thus has the opportunity to exchange arguments with another agent and to build his/her opinion on an innovation from the set of arguments he/she knows. An application of this model is proposed to study the diffusion of communicating water meters by farmers on the Louts River (southwestern France).