This is the second paper from the series of two papers. In the first paper based on the communicative approach the main attributes of soft law in modern legal discourse were considered and their study showed that the modern legal systems moving from mono(state)centricity to a polycentricity. In this paper, through the prism of various legal theories the causes of this phenomenon are discussing. The research shows that the exhaustion of the capacity of the state both in regulation and in dispute resolution dictates the deviation from the legal monism and decentralization of law. It is also showing that some kinds of decentralization of law do not retain legal clarity and rule of law. Decentralization of law by creating a field of homogeneous legal communications does not allow preserving legal clarity, whereas polycentric one does allow.