monism

noun3

1. •
   The doctrine of the oneness and unity of reality, despite the appearance of diversity in the world.

   • Many socialists were tending towards idealistic monism, regarding the world as an integrated progress of man and nature towards final harmony. — 1978
2. •
   The legal doctrine that international law forms part of domestic law automatically after ratification or accession.
3. •
   (historical) The doctrine that there is a single source of political authority, especially that the church is subordinate to the state or vice versa.

   • The same conflict between the monism of temporal theorists and the dualism of ecclesiastical thinkers—the same opposition of organic to symbiotic union—occurred in the ninth century. — 1964