Emergence Theory, also called Emergentism, is a philosophical and scientific theory (already propagated by the Greek philosopher Aristotle) that is about the fact that sovereign entities i.e. phenomena, groups of entities, or systems can have properties or characteristics its separate parts (components) don’t have on their own. That is, the properties of a certain entity or system emerge only when the parts interact together.
Nowadays, for instance, the phenomenon of life is generally considered an “emergent property” of its individual elements, an interactive, interconnected result of chemistry between its constituents. The same counts, for instance, for our consciousness or self-consciousness, which is thought to only emerge as a result of properly functioning body elements.
To say it differently: an emergent property (or characteristic) of a single entity (a single system) or a group of similar or different entities (a composite system) is a property that is not a property of any constituent of that entity or system on its own, but it’s still a feature of that entity or system as a whole.
Nevertheless, it’s also possible to see the Emergence philosophy from another perspective, that is, to consider that the “emergent property” is actually already there, but needs a “vessel” or “vehicle” to become visible, active, or functioning i.e. emergent. For instance, we could propose that the phenomenon of consciousness i.e. awareness already exists, but needs, creates, and maintains a body (let’s say: our brain and nervous system) to express itself and function.
In this particular view, Vital Life Energy, Vital Force, or Life is “already there,” and not a result of “chemistry” of the different parts of a body or entity, but the other way around; the body is a function or even an “emergent property” of Life.