Group decision making is a complex phenomenon that is difficult to model because it depends on rational and irrational factors, personal determination, group dynamics, etc. Interaction is an important stage in this process - as different opinions are sorted out, a shared vision emerges. We model this emergence using the mean field model of phase transition, a well-known approach to disordered, complex systems. Our two scenarios refer to whether, or not, group members feel external influence during the meeting. We discuss our model and use it in simulations to study the dependence of emergence time on group size.