An integrative level is a pattern of organization emerging on pre-existing phenomena of a lower level. Typical examples include life emerging out of non-living substances, and consciousness emerging out of the nervous system. As components combine to produce larger functional wholes in hierarchical series, new properties emerge, and one cannot explain all of the properties at one level from an understanding of the components at the level below. The idea of integrative levels is central to the theory of emergence as integrative levels can be understood as the product of the process of emergence having played out to generate two or more qualitatively different levels of organization.
In a paper in Science Magazine by Alex Novikoff entitled “The concept of integrative levels and biology,”1 The author summarizes the theory as such: “The concept of integrative levels of organization is a general description of the evolution of matter through successive and higher orders of complexity and integration. It views the development of matter, from the cosmological changes resulting in the formation of the earth to the social changes in society, as continuous because it is never ending, and as discontinuous because it passes through a series of different levels of organization-physical, chemical, biological and sociological. In the continual evolution of matter, new levels of complexity are superimposed on the individual units by the organization and integration of those units into a single system, what were wholes on one level become parts on a higher one.
Each level of organization possesses unique properties of structure and behavior which, though depending on the properties of the constituent elements appear only when these elements are combined in the new system. Knowledge of the laws of the lower level is necessary for a full understanding of the higher level, yet the unique properties of phenomena at the higher level can not be predicted, a priori, from the laws of the lower level. The laws describing the unique properties of each level are qualitatively distinct, and their discovery requires methods of research and analysis appropriate to the particular level. The laws express the new organizing relationship, i.e., the reciprocal relationships of elementary units to each other and to the unit system as a whole. The concept of integrative levels recognizes as equally essential for the purpose of scientific analysis both the isolation of the parts of a whole and their integration into the store of the whole.”
Emergence is the central idea behind intergrative levels. Emergence addresses the organization of systems that self-organizes into layers of emergent wholes, systems that function according to nonreducible properties. This means that higher order patterns of a whole functional system, such as an ecosystem or whole societies, cannot be predicted or understood by a simple summation of the parts. These new properties emerge because the components interact, not because the basic nature of the components is changed. Water is more appropriately studied as a whole due to its emergent properties, but in the case of two cups on a table the lack of positive synergy precludes emergence; the system is thus best understood by simply analyzing each of the parts in isolation. To get good answers we must first ask the right questions. Quite different tools are needed for different levels; we do not use a microscope to study an entire ocean, a whole city, or the behavior of carbon dioxide in the atmosphere. For example, because of emergence our progress in solving social or environmental problems can be significantly slowed when the wrong level is focused upon and thus the wrong questions asked.
The theory of integrative levels puts forward a number of principles governing the structure of this hierarchical organization. Firstly, the higher levels depend on the lower levels, which would seem to be quite apparent. Higher level phenomena emerge from more basic constitutions, and without those constituent parts, any form of emergence becomes impossible. This would imply that higher levels in the hierarchy are inherently more precarious due to this dependence on the lower levels. Secondly, the higher up the level the fewer the instances. This again would appear self-evident, as emergence involves a process of synthesis, or merging of different things. On every higher level, the number of elements is thus reduced. Thirdly, the sequence of levels is often described as one of increasing complexity. This is far less self-evident and a somewhat debatable proposition, as it depends on one’s definition of complexity, for which there are a number of different interpretations. One interpretation of complexity that would be congruent with this proposition is the idea that complexity is a combination of both integration and differentiation, which describes a system that has many diverse parts, which in turn are interconnected and interdependent. This is one interpretation of a complex system that is congruent with this hypothesis, because, through the process of synthesis, systems are conceived that have increasingly many parts which are also increasingly interdependent, thus enhancing complexity.
Hierarchy and emergence give rise to the design principle of encapsulation, describing how smaller subsystems are nested or encapsulated within larger structures. Key to this design pattern is the use of abstraction, meaning the successive removal of detail, as smaller locally, specific subcomponents are nested within larger more generic processes and structures. Hierarchical encapsulation through abstraction is central to the structural design of complex systems of all kind and can be seen as a fundamental pattern of functioning ordered systems of complexity, as it works to distribute components out across different levels.
The so-called Parable of the Watchmakers illustrates this: There once were two watchmakers, named Hora and Tempus, who made very fine watches. The phones in their workshops rang frequently; new customers were constantly calling them. However, Hora prospered while Tempus became poorer and poorer. In the end, Tempus lost his shop. What was the reason behind this? The watches consisted of about 1000 parts each. The watches that Tempus made were designed such that, when he had to put down a partly assembled watch (for instance, to answer the phone), it immediately fell into pieces and had to be reassembled from the basic elements. Hora had designed his watches so that he could put together subassemblies of about ten components each. Ten of these subassemblies could be put together to make a larger sub-assembly. Finally, ten of the larger sub-assemblies constituted the whole watch. Each sub-assembly could be put down without falling apart. This is an example of abstraction and encapsulation within a design that is central to dealing with complexity and results in a hierarchy of integrative levels that we see omnipresent in the natural and social world.
This nested hierarchical structure is seen within fractal forms that exhibit self-similarity across various scale of magnitude. Examples within ecosystems include everything from proteins and DNA to the capillaries in mammals, tree canopies, river networks, and mountain ranges. This self-similarity or fractality implies a particular kind of structural composition or dynamic behavior, wherein the fundamental features of the system exhibit an invariant, hierarchical organization that holds over a wide range of spatial scales and can be derived from simple iterative rules.
This process begets the emergence of a new level of organization: a structure that has some integrity to its parts or within which some process takes place, which creates its own distinct pattern. This then feedbacks to shape and constrain the components on the local level. We get the emergence of some process, but for the process to take place there needs to be an enabling structure. That structure then defines some order to the system and the components must differentiate their states to perform the various structural and functional roles required to process the resource on the macro level. This is most evident from the way the human body as a whole regulates every local component of itself to enable global processes, such as respiration and digestion, to take place effectively. This is a micro to macro to micro feedback loop through the many different emergent levels from the cell to tissues to organs and the entire organism.