Political systems can be divided into unitary and pluralistic systems in terms of their tendency towards unificationism and pluralism. Unitarianism in politics is applied to ideas that emphasize the concentration of political power and that sovereignty is limited to the state and its will. In contrast, pluralism insists on the diversity of sources of power and its distribution among rival groups.
The truth is that both approaches have taken the path of extremism and this has faced them with challenges in the field of thought and action. In such circumstances, the necessity of identifying alternatives for them leads us to the idea of ​​"unity in multiplicity" in the theory of Velayat-e-Faqih. In this theory, "unity at the same time as plurality" can be traced in two related areas, namely political structure and political belief and action, and can be considered as one of the functions of Velayat-e-Faqih theory.