Reductionism is a philosophical or scientific theory – depending on what you apply it to. It can be applied to any phenomenon like objects, explanations, theories and meanings.

It says that a system is fully defined and determinate by its elements, parts and they interactions. For example, the temperature of a gas is reduced to nothing beyond the average kinetic energy of its molecules in motion. This theory describes that a system is nothing but the total of its elements. It strongly represents a certain perspective of causality. Every system or context has a causal-deterministic origin.