Part I Theoretical Foundations: The Structural Agency Theory of Consciousness

Editor's Note: Serving as the core program of the entire book, this part collects the foundational papers that establish the theoretical basis of this school of thought. It cements the academic status of "agency" as the causal core of consciousness, serving as the cornerstone upon which the concepts in all subsequent chapters unfold.

Prologue: The Biological–Evolutionary Foundational Paradigm of Embodied Consciousness

Abstract

This paper establishes the Structural Agency Theory of Consciousness (SATC) as a foundational paradigm. It aims to understand consciousness as a hierarchically differentiated, biologically fundamental phenomenon emerging from the evolution of life structures. We argue that the definition of consciousness lies not in subjective experience, symbolic representation, or mere information processing, but in Biological Agency (enactive capacity)—an intrinsic, structure-dependent capacity of living systems that enables them to actively interact with, adapt to, and modify their environment for their own survival. Agency is viewed as a functional attribute encoded by biological structures and expressed across a continuous evolutionary lineage.

This framework is grounded in evolutionary biology, neurodevelopment, and materialist philosophy. It replaces anthropocentric and dualistic explanations with a rigorous biological causal chain: Matter → Structure → Function (Agency). We propose a hierarchical structural model of agency that encompasses sessile life forms (such as plants), locomotive animals with a central nervous system, and humans as a special case—who possess Abstract–Projective Agency, characterized by the externalization of action through tools and symbolic systems. Within this paradigm, consciousness is co-extensive with biological agency, yet exhibits varying degrees of complexity depending on structural organization (particularly the complexity of the nervous system).

This foundational paper defines the ontological commitments, core concepts, evolutionary origins, and methodological boundaries of the Structural Agency Theory of Consciousness, establishing a coherent theoretical foundation for future work in neuroscience, biology, philosophy of mind, and embodied AI.

Keywords: consciousness, agency, enactive capacity, evolutionary biology, neurodevelopment, structuralism, embodied cognition

1. Introduction

The scientific study of consciousness remains fragmented among phenomenological descriptions, information-theoretic abstractions, and cognitive functional modeling. Although these approaches provide valuable descriptive insights, they often fail to anchor consciousness to biological first principles. In particular, many contemporary theories implicitly treat consciousness as an exceptional property that emerges only at high levels of cognition, frequently confining it to humans or human-like systems.

This paper proposes a different starting point. We argue that consciousness must be understood as a biological phenomenon continuous with life itself, emerging through the evolutionary growth of structural complexity rather than appearing as a taxonomic anomaly. To this end, we introduce the Structural Agency Theory of Consciousness, a framework that defines consciousness as the functional expression of Biological Agency, rather than subjective experience or abstract information processing.

Our aim is not to deny phenomenology, cognition, or information processing, but to reconfigure the priority of explanation: phenomenological experience is viewed as a descriptive layer, whereas agency, rooted in biological structure, is identified as the causal foundation of consciousness.

2. Ontological Commitments and Methodological Scope

2.1 Ontological Commitments

1. Material Causality: Only physical structures possess causal efficacy.
2. Structural Functionalism: Biological functions are inherent to and instantiated by physical structures, rather than designated externally.
3. Agency as Biological Function: Agency is a biological function, not a representation or symbolic construct.
4. Non-Dualism: Consciousness has no independent causal status outside of biological agency.

These commitments firmly place the theory within a radical materialist and evolutionary framework, while avoiding reduction to computational or informational abstractions.

2.2 Methodological Boundaries

This framework explicitly rejects explanations of consciousness that rely on:

• Non-structural or non-material causal entities
• Claims of pure informational or symbolic sufficiency
• A dualistic separation between mind and biological substrate

Psychological, social, and environmental factors are acknowledged as regulators of biological structure and development, but not as independent causal sources detached from physical organization.

3. Core Definitions

3.1 Structure

Structure refers to a materially instantiated, evolutionarily stabilized organization that is capable of maintaining metabolic order and engaging in coordinated interactions with the environment.

3.2 Biological Agency (Enactive Capacity)

Biological Agency is defined as the structure-dependent capacity of a living system to initiate, regulate, and maintain interactions with its environment for its own survival.

Within this framework, agency corresponds to what is commonly described as enactive capacity or intrinsic activity, and does not imply deliberation, symbolic reasoning, moral responsibility, or free will.

3.3 Consciousness

Consciousness is the organism-level expression of biological agency, enabled by life structures in their continuous interaction with the environment.

Consequently, consciousness is co-extensive with agency, yet differentiates according to structural organization and complexity. Phenomenological experience, if it exists, is viewed as an emergent descriptive aspect rather than the causal substrate.

4. The Biological Origins of Agency

4.1 Metabolic Order and the Emergence of Agency

The origin of consciousness is inseparable from the origin of life. The earliest forms of agency emerged alongside self-sustaining metabolic structures capable of maintaining a local low-entropy state under global thermodynamic constraints.

At this level, agency manifests as the intrinsic propensity of a structure to preserve its organization through regulated exchange with the environment. This constitutes the most minimal form of consciousness in our framework.

4.2 Genetic Encoding and Structural Constraints

Biological agency is constrained and stabilized by genetic encoding and molecular organization. Disruptions to genetic or protein structures directly impair agency by undermining the structural foundation of metabolic regulation.

This level establishes the evolutionary continuity of consciousness: later, more complex forms of agency do not replace this foundation, but rather elaborate upon it.

5. The Evolutionary Differentiation of Agency: A Structural Continuum

Biological agency is not binary, but is expressed along a continuum determined by structural complexity. We identify four primary evolutionary stages, defined by structural transitions rather than anthropocentric criteria.

5.1 Level 0: Pre-Agentive Life

This level includes the least organized life forms, where metabolic maintenance occurs without organism-level behavioral integration. If agency is present, it is local rather than globally coordinated.

5.2 Level I: Distributed Sessile Agency

Plants are paradigmatic of distributed biological agency. They are sessile life forms whose organism-level location remains largely fixed throughout their life cycle. However, they exhibit clear agency through environmental sensing, adaptive growth, resource optimization, and long-term environmental modification.

Plant agency is non-locomotive and growth-mediated, operating over extended timescales rather than through rapid movement.

5.3 Level II: Centralized Sensorimotor Agency

With the evolution of the central nervous system, agency underwent a qualitative shift. Animals at this level possess:

• Perception–action loops
• Locomotive capacity
• Learning and behavioral flexibility

Agency here is centralized, rapid, and spatially mobile, enabling active exploration and short-term goal-directed behavior.

5.4 Level III: Abstract–Projective Agency

Humans represent a further structural shift, characterized by the expansion of neural architecture—particularly the prefrontal cortex—supporting abstraction, long-term planning, and counterfactual modeling.

A defining feature of this level is the externalization of agency through tools and symbolic systems. Based on a materialist reinterpretation of Marx's insights, the creation and use of tools is not viewed as the origin of consciousness, but rather as structural evidence of abstract–projective agency transcending immediate sensorimotor coupling.

6. Neurodevelopment and the Expression of Agency

The development of consciousness within an individual organism is the progressive unfolding of structurally encoded agency. Neurodevelopmental processes—including neurogenesis, synaptogenesis, and circuit specialization—provide the physical substrate for increasingly complex agency.

Environmental factors act as triggers and regulators, shaping the expression of pre-coded structures without constituting an independent causal origin of consciousness.

7. Damage, Pathology, and Causal Explanation

Disorders of consciousness and agency must be understood as consequences of structural disruption. Genetic abnormalities, developmental failures, damage, and neurodegeneration impair agency by dismantling its biological substrate.

Psychological and social factors influence consciousness only to the extent that they affect neurodevelopment and structural integrity. Consequently, this framework excludes explanations that decouple psychological phenomena from material causality, while retaining the relevance of environmental regulation.

8. Implications for Artificial and Synthetic Agency

The Structural Agency Theory of Consciousness has direct implications for AI. If consciousness is rooted in biological agency, then artificial systems pursuing human-level intelligence must move beyond disembodied software architectures.

Future artificial general intelligence (AGI) will require embodied, structurally complex, multi-material systems capable of sustaining persistent interaction loops with their environment, approximating the structural conditions of Level III agency.

9. Conclusion

The Structural Agency Theory of Consciousness reframes consciousness as a hierarchical biological phenomenon rooted in the evolution of life structures. By identifying agency as the causal core of consciousness, this paradigm restores continuity between life, behavior, and cognition, while rejecting anthropocentric and dualistic assumptions.

Human consciousness is not a metaphysical exception, but a highly elaborated form of biological agency. This foundational framework establishes a coherent basis for future empirical, theoretical, and applied research in biology, neuroscience, philosophy, and AI.