The world possesses a hierarchical structure and evolves through emergence. Its levels are the result of emergence, and possess unique properties and functions which their components and emergent bases do not. Each of these levels also possesses basic laws or rules which cannot be logically deduced from other levels, and evince downward causation. Therefore, there are non-linear causal networks among the levels of complex systems in which causal reductionism does not hold. The hierarchical structure is formed in accordance with the increasing organized complexity of the objects, so that different levels give birth to different disciplines, and different disciplines have their own theoretical autonomy and independence. Therefore, theories across different levels are essentially irreducible, and any apparent case of reduction may only be so in the sense of a partial reduction. Emergence-evolution-hierarchy ontology and multi-synergic holism is compatible with reductionism even as it transcends it.