Why APS Is Not Hierarchical

Abstract

APS rejects the treatment of hierarchy as an ontological or explanatory principle in biology. While hierarchical language can function as a descriptive shorthand, living systems are not organised into discrete tiers of causal authority. APS instead understands biological organisation as continuous, scale-coupled, and constraint-mediated. Apparent levels of organisation are explanatory abstractions imposed upon dynamically integrated processes distributed across space and time.

The Appeal of Hierarchy in Biology

Biology is often described in hierarchical terms. Textbooks speak of genes, cells, tissues, organs, organisms, populations, and ecosystems as “levels of organisation.” This language is familiar, intuitive, and often pedagogically useful. It provides a convenient shorthand for discussing systems that differ in spatial extent, temporal persistence, and descriptive granularity.

APS does not deny that such language can be useful descriptively.

The problem arises when descriptive hierarchy becomes explanatory ontology.

APS rejects the idea that living systems are literally organised into discrete tiers of causal authority or explanatory priority. Biological organisation is not fundamentally stratified into stacked levels through which causation flows upward or downward. Instead, living systems are organised through continuous, scale-coupled, constraint-mediated processes distributed across space and time.

APS Box — Hierarchy vs Scale

Biological systems are often described using hierarchical language:

lower and higher levels
simple and complex forms
or upward-building layers of organisation

APS treats such descriptions primarily as explanatory conveniences rather than as literal features of biological reality.

In place of hierarchy, APS uses the concept of scale.

Living systems are organised across continuously interacting spatial and temporal scales, linked through processes of scale-coupling and reciprocal organisational dependence. Molecular, physiological, behavioural, ecological, and evolutionary processes are not separate ontological layers but dynamically integrated aspects of continuous biological organisation.

APS therefore rejects the idea that biological explanation must proceed:

from lower to higher levels
from more fundamental to less fundamental domains
or through unidirectional chains of causation

Instead, biological organisation is understood through reciprocal relations distributed across interacting scales.

APS also distinguishes scale from resolution.

Scale refers to the spatiotemporal organisation of biological activity itself. Resolution refers to the granularity at which that organisation is described or analysed. What appear as “levels” often reflect differences in explanatory resolution rather than discrete layers of reality.

This shift matters because hierarchical language can unintentionally imply:

privileged explanatory domains
ontological stratification
or one-way causal determination

APS instead understands living systems as dynamically organised, scale-coupled processes sustained through reciprocal organisational relations.

Key Point. Biological organisation varies across interacting scales, not through ranked ontological levels or hierarchical layers of reality.

Hierarchy as an Epistemic Convenience

What biologists call “levels” are usually explanatory abstractions rather than ontological divisions within nature itself.

Researchers partition complex systems into components and domains in order to:

simplify description
isolate mechanisms
construct models
organise explanation

These abstractions are often useful and sometimes indispensable.

However, the partitions imposed for explanatory purposes do not themselves constitute the organisation of living systems. Biological processes do not unfold within neatly separated strata. Molecular, physiological, developmental, behavioural, and ecological processes continuously interact and mutually constrain one another across scale.

APS therefore distinguishes between:

explanatory perspective
and biological organisation itself

Confusing the two produces the illusion that life is composed of discrete levels rather than dynamically integrated processes.

What Hierarchical Thinking Smuggles In

Hierarchical language often carries implicit assumptions:

that biological systems are arranged into discrete tiers
that some levels possess greater causal authority than others
that explanation proceeds by identifying the “correct” level
that causation flows upward or downward between levels
that agency appears only at sufficiently “high” levels of complexity

These assumptions are rarely defended explicitly, yet they strongly shape biological reasoning.

APS treats these assumptions as conceptual artefacts rather than discoveries about living organisation.

Living systems exhibit nested organisation, differences in scale, and asymmetries of influence. However, none of these require ontologically distinct strata or privileged levels of causation.

From Levels to Scale-Coupled Organisation

APS replaces level-based thinking with the concepts of:

scale
resolution
organisational coupling
constraint relations

What are traditionally called “levels” are more precisely understood as differences in:

spatial–temporal extent
descriptive granularity
organisational integration
persistence across time

Living organisation is therefore not hierarchical in the sense of layered control architectures. Instead, it is scale-coupled: processes occurring across different extents mutually constrain and stabilise one another within viability-oriented organisation.

Constraint relations propagate across scale without requiring privileged levels of control.

Why Hierarchy Misleads Accounts of Causation

Hierarchical thinking encourages the language of “bottom-up” and “top-down” causation.

APS rejects this framing.

Biological causation is reciprocal, distributed, and constraint-mediated. Molecular activity shapes organismal behaviour, while organismal activity reorganises molecular conditions. Developmental, physiological, behavioural, and ecological processes continuously interact without occupying ontologically separate domains.

No single scale possesses explanatory priority in principle.

What matters is how processes are coupled within organised systems capable of sustaining viability.

APS therefore replaces hierarchical causation with mutual constraint across scale.

Why Hierarchy Misleads Accounts of Agency

Hierarchical models are especially misleading when discussing biological agency.

Agency is often treated as something that emerges only at “higher levels” once sufficient complexity accumulates. Smaller-scale processes are then interpreted as passive mechanisms controlled from above.

APS rejects this picture.

Agency is not a property of a level. It is a mode of organisation.

Where viability-oriented, constraint-closed organisation exists, systems can succeed or fail relative to the maintenance of their own persistence. Agency therefore depends upon organisational relations, not hierarchical position.

Different forms of agency may exist across different scales and forms of organisation without requiring ontological stratification.

Organisational Domains and Explanatory Perspective

APS distinguishes scale from explanatory domain.

Scale concerns how activity is organised across space and time.

An explanatory domain concerns how that organisation is being described or analysed:

mechanistically
physiologically
evolutionarily
cognitively
ecologically
agentially

Multiple explanatory domains may apply simultaneously to the same organised process without introducing new ontological layers.

This distinction allows APS to preserve explanatory pluralism without reifying hierarchy.

Constraint Relations Replace Hierarchical Control

Hierarchical models often smuggle in metaphors of command and control.

APS instead emphasises constraints.

Constraints shape which processes can occur, while processes in turn maintain, transform, or dissolve those constraints. Regulation therefore emerges through reciprocal organisational relations rather than through layered command architectures.

Constraint closure explains how living systems maintain themselves without invoking hierarchical controllers.

This also explains why biological organisation is historically and dynamically stable despite continuous material turnover.

Translating Standard Biological Language

APS does not prohibit the use of hierarchical terminology.

Instead, it treats “levels of organisation” as a translation problem.

Where conventional biology refers to levels, APS translates this into:

differences of scale
differences of descriptive resolution
differences of organisational coupling
differences of explanatory perspective

This preserves the empirical usefulness of hierarchical language while avoiding misleading ontological commitments.

Summary

Hierarchy is a useful descriptive shorthand in biology, but it becomes misleading when treated as an explanatory principle or ontological structure.

Living systems are not organised into discrete tiers of causal authority. They are organised through continuous, scale-coupled, constraint-mediated processes that sustain viability across space and time.

APS therefore replaces hierarchy with an account of biological organisation grounded in:

scale
organisational coupling
constraint relations
and viability-oriented persistence

Life is not a stack of levels.

It is organised activity across scale.

Key Points