The World Is a Hierarchy of Systems

#model13 mentions

When thinking about ontology (put simply, what the world consists of), we can start with the basic fact that there is difference in the world – that “something can be distinguished from everything else”.Friston (2019), 4, who develops a formally rigorous framework based on an (albeit implicit) ontology similar to the one outlined here. René Thom (1975, 1) makes the same point: “Whatever is the ultimate nature of reality […], it is indisputable that our universe is not chaos. We perceive beings, objects, things to which we give names. These beings or things are forms or structures endowed with a degree of stability […].”

We call such distinguishable somethings Systems. Systems are differentiated by their boundary, i.e. by what is and what is not part of them. Each item that is part of a system can itself be understood as a system. This means systems are composed of smaller systems and form larger ones.

By positing that this hierarchy of systems extends ad infinitum, one “eludes the question ‘what is a thing?’ by composing things from … smaller things. By induction, we have [systems] all the way down, which means one never has to specify the nature of things.”Friston 2019, 4

We want to Use a parsimonious and productive ontology, and this view fulfils both criteria:

All there is are systems composed of systemsThis is in effect already Spinoza’s ontology: “singular things … exist … in several scales and various levels of vertical integration. Individuals in one level are components of higher-level individuals, so that if ‘we thus continue to infinity, we shall readily conceive the whole of Nature as one individual whose parts – that is, all the constituent bodies – vary in infinite ways without any change in the individual as a whole’.” (Nunes 2021, ch. 4)

– in other words, on the most abstract level, our only Ontological Commitment are systems. There are no intrinsic qualities or identities beyond that. This is extremely parsimonious.

At the same time, this ontology allows for everything to exist as a system in its own right, not just as our projection: “there is no privileged scale, other than the scale that ‘matters’ for a thing in question”.ibid., 7

This avoids top-down Reductionism in favour of Causal Emergence.This is the key difference to Dennett’s “real patterns”: In a systems ontology, systems are real; in Dennett’s version, they are only patterns we see in a world that is ultimately made up of elementary particles, quantum fields, higher-dimensional strings or similar. A systems ontology is closer to Ross’s “rainforest realism”, which claims that “reality is composed of real patterns all the way down” (Ross 2000, 160).

It also makes our ontology more productive: We can generate more insights because we can describe systems and their respective System Dynamics on an indefinite number of levels. This helps us identify patterns that are hard to discern from a more traditional perspective.

At the level of the system, the internal states of its components are hidden by their boundaries – they are causally irrelevant and can be abstracted away in our Models of the system.

The components’ boundaries in turn are dependent on their Attractors, i.e. their sets of stable states. These are also a prerequisite for system composition: a system can only connect with other systems to build something more complex if it is stable.

This makes system boundaries and attractors the joints at which to carve reality. Tracking them makes models useful and thus representational.

The technical apparatus to describe the transition between the levels of the hierarchy is Renormalisation.Or, more technically, the renormalisation group. (Wikipedia, Kostya 2011)

Since Systems live in state spaces, there is a corresponding hierarchy of State Spaces that makes up the fundamental space of our world.