Systems Theory and the Study of Organisation

Systems theory encompasses a broad set of approaches that model phenomena in terms of interacting components, feedback loops, and dynamic behaviour. In biology, these approaches have been central to moving beyond strictly reductionist explanations.

Rather than analysing isolated parts, systems approaches examine how interactions among components produce organised behaviour over time. Concepts such as feedback, regulation, stability, and emergence are central to this perspective.

These tools have proven extremely powerful for describing biological systems, from metabolic networks to ecological dynamics. In this respect, systems theory captures an important aspect of living organisation: that biological phenomena are distributed across interacting processes rather than located in isolated components.

Points of Convergence with APS

APS shares several core commitments with systems approaches.

Both reject the idea that biological explanation can be reduced to isolated parts. Both emphasise that organisation arises through interaction, and that behaviour must be understood in terms of processes unfolding across time and scale.

Systems concepts such as feedback, coupling, and dynamic stability align naturally with APS descriptions of how living systems sustain themselves. In particular, the emphasis on distributed causation resonates with APS’s view that agency, process, and scale are co-constitutive.

For these reasons, systems theory provides an important descriptive and analytical toolkit within an APS framework.

The Limits of Systems Theory

Despite these strengths, systems theory typically remains normatively neutral. It can describe how systems behave, but it does not, by itself, specify why certain states or processes matter for the system.

In many systems approaches, the definition of the system itself—its boundaries, variables, and relevant processes—is introduced by the observer. This is sufficient for modelling and analysis, but it does not establish what makes a system biological.

As a result, systems theory can be applied equally to:

  • living organisms
  • mechanical devices
  • economic systems
  • climate dynamics

The same formal tools describe all of these cases, but they do not distinguish between them in terms of their mode of organisation.

APS: From Systems to Biological Organisation

APS incorporates the insights of systems theory while specifying the conditions under which a system counts as biological.

In APS, biological systems are not defined by complexity, feedback, or dynamic behaviour alone. They are defined by viability-oriented, constraint-closed organisation.

This introduces a fundamental distinction:

  • In general systems theory, interactions can be described without reference to what is at stake for the system
  • In APS, interactions are organised around the maintenance of the system’s own persistence

This gives rise to endogenous normativity. Processes matter because they contribute to or undermine the continued viability of the system. This is not imposed by the observer but arises from the organisation of the system itself.

System Boundaries and Organisational Closure

A central difference concerns how system boundaries are understood.

In many systems approaches, boundaries are defined for analytical convenience. The system is whatever is selected for study, and its limits depend on the modelling framework.

In APS, boundaries are not arbitrary. They are determined by constraint-closed organisation—the network of processes that mutually sustain one another and collectively maintain the system’s persistence.

This means that a biological system is not simply a set of interacting components but a self-delimiting organisation. Its boundaries are enacted through its own activity, not imposed from outside.

Agency and the Distinction Between Living and Non-Living Systems

Because systems theory is normatively neutral, it does not by itself distinguish between living and non-living systems.

APS introduces this distinction through the concept of biological agency. Living systems actively regulate the conditions of their own persistence. They do not merely exhibit dynamic behaviour; they sustain themselves through ongoing, viability-oriented activity.

This distinguishes biological systems from:

  • machines, which operate according to externally imposed functions
  • physical systems, which evolve according to general laws without self-maintained organisation

In APS terms, agency is not an additional feature layered onto a system. It is the activity through which a system maintains itself as a system.

Systems Theory Within APS

From an APS perspective, systems theory is best understood as a descriptive and analytical layer rather than a complete account of life.

It provides tools for modelling:

  • interactions
  • feedback structures
  • dynamical trajectories

APS situates these tools within a broader explanatory framework that specifies:

  • why certain processes matter (viability)
  • how organisation is maintained (constraint closure)
  • what distinguishes living systems (agency)

In this way, systems theory is neither rejected nor replaced. It is integrated and grounded within an account of biological organisation.

In Brief

Systems theory provides powerful tools for describing interaction and dynamics, but it does not by itself define what makes a system biological. APS incorporates systems insights while grounding them in viability-oriented, constraint-closed organisation. Biological systems are distinguished not by complexity or feedback alone, but by endogenous normativity and agency.