Where this article fits: What Is APS? introduces the framework, while Understanding APS explains how readers can navigate its major domains and pathways.

Naturalising Life serves a different purpose. It explains how APS develops and stabilises biological concepts, and how difficult phenomena such as purpose, agency, cognition, meaning, and mind become scientifically intelligible.

Readers seeking APS’s explanatory foundations should continue to How APS Explains Life. Readers seeking the full conceptual architecture of the framework should continue to The Core Structure of APS.

Introduction - Why Life Needs Naturalising

Biology seeks to explain living systems, yet some of its most important concepts remain persistently contested. Terms such as purpose, agency, cognition, meaning, and mind are widely used in scientific and philosophical discussions, but disagreement often arises over what these concepts actually refer to and whether they can be accommodated within a naturalistic understanding of life. The result is a recurring tension within biology. On the one hand, these concepts appear indispensable for describing the behaviour and organisation of living systems. On the other hand, they are frequently regarded with suspicion because they seem to carry anthropomorphic, metaphysical, or teleological assumptions that sit uneasily within scientific explanation.

This tension is not unique to any particular concept. Discussions of purpose often become entangled with questions of design or intention. Agency is frequently associated with conscious choice and therefore treated as inappropriate outside human contexts. Cognition is commonly linked to brains and nervous systems, making its application to simpler organisms controversial. Meaning is often regarded as a linguistic or psychological phenomenon rather than a biological one. Mind remains one of the most challenging concepts in science, situated at the intersection of biology, psychology, philosophy, and neuroscience. Despite substantial empirical progress in all of these areas, many of the underlying conceptual disputes remain unresolved.

The persistence of these debates suggests that the difficulty may not lie solely in a lack of evidence. Biology possesses extensive knowledge about organismal behaviour, physiological regulation, development, adaptation, and evolution. Yet disagreement often continues even when relevant empirical findings are widely accepted. This observation raises a different possibility: perhaps some scientific difficulties arise not because the phenomena themselves are inaccessible, but because the concepts used to understand them remain unstable.

APS approaches this possibility directly. Rather than treating concepts such as purpose, agency, cognition, and meaning as either self-evident realities or problematic residues of pre-scientific thinking, APS asks how such concepts become scientifically usable in the first place. From this perspective, the challenge is not simply to explain biological phenomena but to develop conceptual frameworks capable of rendering those phenomena intelligible.

Naturalising life, as the term is used here, refers to this broader project. It is the process of reconstructing difficult concepts as features of organised living systems so that they can participate in scientific explanation without being reduced away or elevated beyond nature. In this sense, naturalisation is not merely a philosophical exercise. It is an essential part of scientific understanding itself. Before a phenomenon can be explained, it must first become a coherent object of inquiry.

This article argues that APS advances biological understanding through two related processes: naturalisation and conceptual closure. Naturalisation reconstructs difficult concepts as features of living organisation, while conceptual closure stabilises those concepts within a coherent explanatory framework. Together these processes transform phenomena that appear ambiguous, metaphysical, or irreducible into scientifically intelligible objects of investigation. More broadly, they reveal APS as a programme for rendering life scientifically intelligible.

The Problem of Unstable Biological Concepts

Scientific progress is often portrayed as the accumulation of empirical knowledge. New observations are made, hypotheses are tested, and explanations become increasingly refined. While this picture captures an important aspect of science, it does not fully explain why some debates persist despite extensive empirical success. In many cases, scientific difficulties arise not because evidence is lacking but because the concepts used to organise that evidence remain unstable.

Conceptual instability occurs when a concept lacks a sufficiently clear and coherent role within an explanatory framework. Such concepts may be used widely while carrying multiple meanings, ambiguous boundaries, or conflicting assumptions. Different researchers may employ the same term while referring to different phenomena, or they may disagree about whether the concept corresponds to anything scientifically real at all. Under these conditions, empirical findings often fail to resolve disputes because the underlying conceptual framework remains unsettled.

Many of biology’s most persistent debates exhibit this pattern. Purpose, for example, is indispensable in descriptions of organismal behaviour, development, and adaptation. Organisms appear to regulate their activities in ways that contribute to survival, reproduction, and persistence. Yet the concept remains controversial because it has historically been associated with design, intention, or final causes. As a result, discussions of purpose frequently oscillate between uncritical acceptance and complete rejection.

Agency presents a similar challenge. Living systems actively regulate themselves, respond to changing conditions, and modify their environments. Nevertheless, agency is often regarded as inappropriate outside human contexts because it is assumed to require conscious intention. The concept therefore becomes unstable, caught between everyday intuitions and scientific caution.

Cognition provides another example. Cognitive processes are traditionally associated with brains, nervous systems, and conscious thought. Yet research increasingly demonstrates sophisticated forms of information processing, memory-like behaviour, learning, and adaptive responsiveness in organisms that lack nervous systems. The resulting debate is not simply empirical. It concerns what cognition is and whether existing concepts are adequate for describing it.

Meaning and mind exhibit similar difficulties. Meaning is often treated as a linguistic or psychological phenomenon, while mind is frequently regarded as either a subjective mystery or a purely neural process. In both cases, disagreements arise not only from competing explanations but from uncertainty regarding the concepts themselves.

These examples illustrate a broader pattern. Concepts become unstable when they inherit assumptions from earlier intellectual traditions that no longer fit comfortably within contemporary biology. Anthropomorphic interpretations, metaphysical commitments, reductionist expectations, and disciplinary boundaries can all contribute to instability. The concept continues to be used because it captures something important, yet its scientific status remains uncertain.

From the perspective of APS, this situation suggests that biological understanding involves more than the collection of data. It also requires the development of concepts capable of organising observations into coherent explanatory structures. Scientific progress therefore depends not only on empirical investigation but also on conceptual work. Before a phenomenon can become fully intelligible, the concepts used to describe it must acquire sufficient stability to support explanation.

This observation does not imply that concepts are independent of evidence. On the contrary, conceptual development and empirical investigation continually influence one another. However, it does suggest that some scientific controversies persist because conceptual development lags behind empirical discovery. In such cases, the challenge is not merely to gather more data but to construct concepts capable of integrating what is already known.

APS begins from this premise. Many of the most difficult biological concepts remain contested not because they refer to unreal phenomena, but because they have not yet achieved a sufficiently stable scientific form. The task of naturalisation is therefore not to invent new phenomena but to develop concepts capable of making existing phenomena intelligible.

Traditional Responses and Their Limits

Attempts to address difficult biological concepts have generally followed several well-established strategies. These approaches have contributed important insights, yet each leaves unresolved questions that continue to motivate contemporary debate.

One response has been reductionism. Reductionist approaches seek to explain biological phenomena entirely in terms of their constituent parts and underlying mechanisms. Purpose becomes the outcome of evolutionary processes, cognition becomes neural activity, and agency becomes the behaviour of molecular systems. Reductionism has generated enormous scientific advances and remains indispensable for understanding biological mechanisms. However, it often struggles to account for higher-order organisational properties without implicitly reintroducing the concepts it seeks to replace. Describing the molecular basis of agency, for example, does not necessarily explain why organised systems exhibit agential behaviour.

A second response has been elimination. Rather than attempting to explain concepts such as purpose or agency, eliminative approaches argue that such concepts should be abandoned altogether. On this view, they reflect outdated modes of thinking that will eventually be replaced by more precise scientific language. Yet elimination faces a persistent difficulty: many of the concepts targeted for removal continue to perform important explanatory functions. Organisms do appear directed toward maintaining viability. They do regulate their activities in relation to changing conditions. Eliminating the concepts does not eliminate the phenomena that motivated them.

Mechanistic approaches have often sought a middle path. Rather than reducing biological systems to their constituent parts, mechanistic explanations emphasise organised interactions among components. This perspective has greatly enriched biological explanation by highlighting the importance of organisation, regulation, and system dynamics. Nevertheless, mechanistic descriptions alone do not always resolve conceptual questions. A detailed account of how a process operates may still leave uncertainty about how that process should be conceptualised.

Emergentist approaches address this difficulty by emphasising the appearance of novel properties at higher levels of organisation. Agency, cognition, and mind are often treated as emergent features of complex systems. While emergence captures an important aspect of biological organisation, it can sometimes function more as a label than an explanation. Identifying a phenomenon as emergent does not necessarily clarify its nature or establish its relationship to other concepts.

Functionalist perspectives focus on what biological systems do rather than what they are made of. This approach has been particularly influential in discussions of cognition, purpose, and information processing. Functionalism provides powerful tools for understanding biological organisation, but it often leaves open the question of why particular functions matter biologically. APS addresses this issue by grounding function in the viability-oriented organisation of living systems.

Physicalist approaches emphasise the continuity between biology and the physical sciences. APS fully accepts this continuity. Living systems are physical systems, and biological phenomena must ultimately be compatible with physical reality. However, compatibility with physics does not by itself provide an adequate conceptual framework for understanding life. Biological organisation introduces patterns, relationships, and forms of regulation that require their own explanatory treatment.

Finally, dualistic approaches attempt to preserve difficult concepts by separating them from the natural world altogether. Purpose, meaning, mind, and consciousness are sometimes treated as fundamentally distinct from biological processes. While such approaches preserve the phenomena, they do so at the cost of scientific integration. The resulting concepts remain isolated from the explanatory framework of biology.

APS does not reject the contributions of these traditions. Reduction, mechanism, emergence, function, and physical continuity all play important roles in biological explanation. The question APS raises is different. Rather than asking which explanatory strategy is correct, APS asks how concepts become scientifically usable. The challenge is not merely to choose between reduction and emergence, mechanism and function, or physicalism and dualism. It is to understand how concepts such as purpose, agency, cognition, and meaning can be reconstructed as coherent features of living organisation.

This shift in focus marks the starting point for naturalisation. The problem is not simply explanatory. It is conceptual. Before difficult biological phenomena can become fully intelligible, the concepts used to describe them must first acquire a stable place within a broader understanding of life. The next section examines how APS approaches this task through the process of naturalisation itself.

Naturalisation as Concept Formation

If conceptual instability is part of the reason why certain biological debates persist, then an important question follows: how do concepts become scientifically usable in the first place? APS approaches this question through the idea of naturalisation. In its broadest sense, naturalisation refers to the process by which phenomena that appear mysterious, anthropomorphic, metaphysical, or otherwise resistant to scientific treatment are reconstructed as features of the natural world. Within biology, naturalisation is not primarily concerned with eliminating difficult concepts but with making them intelligible as aspects of living organisation.

Naturalisation becomes necessary whenever a concept captures something important about biological reality but remains scientifically unstable. Concepts such as purpose, agency, cognition, and meaning persist because they refer to observable features of living systems. Organisms regulate their activities, pursue resources, respond to changing conditions, discriminate among environmental signals, and maintain forms of organisation that appear directed and adaptive. The difficulty lies not in the existence of these phenomena but in determining how they should be understood. Scientific progress therefore requires more than accumulating evidence about them. It requires concepts capable of relating them coherently to broader biological theory.

This process differs from reduction. Reduction seeks to explain phenomena in terms of more fundamental components or mechanisms. Such explanations are often indispensable. Understanding the molecular basis of cellular regulation, the neural basis of behaviour, or the physiological basis of perception can reveal important aspects of biological organisation. Yet reduction alone does not resolve conceptual questions. Explaining the mechanisms involved in a process does not necessarily establish how that process should be interpreted. A detailed account of neural activity, for example, does not by itself determine what cognition is, just as an account of molecular interactions does not by itself determine what agency is. Naturalisation therefore addresses a different problem. Rather than asking how a phenomenon is physically realised, it asks how that phenomenon can be understood as a coherent feature of living systems.

Naturalisation also differs from elimination. Eliminative strategies often arise when a concept appears theoretically problematic. If agency seems anthropomorphic, purpose appears teleological, or meaning appears irreducibly mental, one response is to abandon the concepts altogether. The difficulty with this approach is that the phenomena motivating the concepts do not disappear. Living systems continue to exhibit organised, adaptive, and context-sensitive behaviour. Eliminating the vocabulary may remove conceptual discomfort, but it often leaves biology without adequate ways of describing important features of life. Naturalisation seeks an alternative path. Rather than discarding difficult concepts, it reconstructs them in forms that can participate in scientific explanation.

APS applies this strategy repeatedly across the framework. Purpose, for example, is not treated as evidence of design, conscious intention, or externally imposed goals. Instead, it is reconstructed as a feature of viability-oriented organisation. Organisms act in ways that contribute to the maintenance and continuation of living systems, and this directedness can be understood without invoking foresight or final causes. Similarly, agency is not restricted to conscious choice or human deliberation. APS naturalises agency by understanding it as the capacity of living systems to initiate, regulate, and coordinate activities that sustain their organisation under changing conditions. What appears at first glance to be an exclusively human concept becomes intelligible as a general feature of life.

The same process applies to cognition. Traditional accounts often associate cognition with brains, representation, or conscious thought. APS begins instead with the observation that living systems must continuously monitor conditions, discriminate among relevant signals, and adjust their behaviour in ways that support continued functioning. Cognition is therefore reconstructed as adaptive information processing and evaluative coordination within living systems. This does not erase the distinctive features of human cognition, but it places them within a broader biological continuum.

Meaning undergoes a similar transformation. Rather than beginning with language, symbols, or subjective interpretation, APS starts with the fact that organisms encounter the world in terms of biological significance. Environmental conditions are not merely present; they matter differently depending on their consequences for viability and adaptive persistence. Meaning is therefore naturalised as significance-for-an-agent, emerging from the relationship between living systems and the conditions that affect their continued existence.

In each case, naturalisation does not eliminate the phenomenon or reduce it to something else. Instead, it reconstructs the phenomenon as a feature of organised living systems. Concepts that once appeared ambiguous or scientifically problematic acquire biological grounding and become capable of participating in explanation. Yet biological grounding alone does not guarantee conceptual stability. A concept may be naturalised while remaining contested, ambiguous, or poorly integrated with related ideas. Many contemporary debates illustrate precisely this situation. Concepts such as information, function, intelligence, and consciousness have all undergone significant naturalisation, yet disagreement persists regarding their interpretation and explanatory role. Naturalisation therefore appears necessary for scientific understanding, but it is not sufficient. A further process is required if concepts are to become stable components of an explanatory framework.

Conceptual Closure as Concept Stabilisation

The transition from biological grounding to scientific understanding involves more than the formation of concepts. Concepts must also acquire sufficient stability to perform explanatory work. APS approaches this issue through the idea of conceptual closure. The term is not intended to denote a final or definitive state, nor is it offered as a claim about how science inevitably proceeds. Rather, it functions as an analytical concept that helps explain how scientific concepts become stable enough to support coherent understanding.

Conceptual closure refers to the gradual stabilisation of a concept within an explanatory framework. A concept achieves closure when it possesses a sufficiently clear role, sufficiently well-defined boundaries, and sufficiently strong relationships to neighbouring concepts that it can be used consistently in explanation and investigation. Closure is therefore not a single event but a developmental process through which concepts become integrated into scientific understanding.

Several features contribute to this process. Biological grounding is one of them. Concepts that lack any connection to observable phenomena struggle to acquire explanatory significance. However, grounding alone is insufficient. A concept must also occupy a recognisable explanatory role. It must help explain something rather than merely label it. In addition, concepts require boundaries that distinguish them from related ideas without isolating them completely. Finally, they must become integrated into a wider network of concepts, theories, and observations. A concept that remains disconnected from neighbouring explanatory structures is unlikely to achieve lasting stability.

Conceptual closure should not be confused with definition. Scientific concepts may possess formal definitions while remaining deeply contested. Nor should closure be equated with consensus. Scientists may agree on terminology while continuing to disagree about what a concept signifies. Closure is also distinct from explanation. A phenomenon may be partially explained using concepts whose own status remains uncertain. Likewise, closure should not be mistaken for finality. Scientific concepts remain open to revision, refinement, and reinterpretation. Closure concerns stability rather than permanence.

Perhaps most importantly, conceptual closure is not equivalent to complete explanation. Scientific understanding often develops gradually. A phenomenon may become sufficiently intelligible to support productive investigation long before every aspect of it is fully explained. This distinction is especially relevant for complex concepts such as consciousness, where complete explanation remains elusive despite substantial theoretical and empirical progress. The absence of complete explanation does not imply the absence of understanding.

For this reason, closure is best viewed as existing along a continuum rather than as a binary condition. Some concepts exhibit relatively high degrees of closure. The concept of the organism, for example, possesses extensive biological grounding, a well-established explanatory role, and deep integration with multiple areas of biology. Although debates remain regarding particular cases and definitions, the concept functions with considerable stability. Other concepts exhibit more intermediate forms of closure. Species provides a useful example. Biological, ecological, evolutionary, and phylogenetic approaches have each contributed to understanding, yet disagreements concerning species boundaries and criteria persist. The concept remains scientifically productive while retaining a degree of instability. At the opposite end of the continuum lie concepts such as consciousness or awareness, where competing interpretations continue to coexist and conceptual boundaries remain highly contested.

Viewing closure in this way helps illuminate why some scientific debates persist despite extensive empirical progress. In many cases the issue is not a lack of evidence but an incomplete process of conceptual stabilisation. New data may accumulate rapidly while uncertainty remains regarding how a concept should be interpreted, related to other concepts, or incorporated into a broader explanatory framework. Scientific progress therefore involves not only the acquisition of knowledge but also the gradual development of conceptual structures capable of organising that knowledge.

From the perspective of APS, naturalisation and conceptual closure perform complementary functions. Naturalisation forms concepts by reconstructing difficult phenomena as features of living organisation. Conceptual closure stabilises those concepts by integrating them into coherent explanatory structures. TTogether they enable a third outcome: scientific intelligibility. Scientific intelligibility is the condition in which a phenomenon becomes available to systematic understanding. A phenomenon may be observable, measurable, and even partially explained while remaining conceptually unstable. Intelligibility emerges when concepts acquire sufficient grounding, coherence, and explanatory integration to support investigation, comparison, and explanation.

Naturalisation and conceptual closure are therefore not ends in themselves. Their significance lies in making biological phenomena increasingly understandable. Concepts become useful not merely because they are biologically grounded or theoretically stable, but because these developments allow previously difficult phenomena to participate in scientific inquiry.

Viewed in this light, APS can be understood as more than a framework for describing life. It is also a framework for understanding how biological concepts develop and become scientifically usable. The recurring appearance of naturalisation and conceptual closure across the framework suggests that they are not isolated operations but components of a broader intellectual programme. The next section examines this programme directly by exploring APS as a systematic process of integrative naturalisation.

APS as a Programme of Integrative Naturalisation

The concepts discussed in the preceding sections are often treated as separate problems. Purpose belongs to discussions of teleology, agency to questions of action and autonomy, cognition to debates concerning information processing and intelligence, meaning to philosophy of language and mind, and consciousness to the philosophy of mind. From this perspective, each concept appears to require its own explanatory framework. APS approaches the situation differently. While recognising the distinctiveness of these phenomena, it suggests that many of the associated difficulties arise from a common source: the challenge of developing concepts capable of rendering complex forms of living organisation scientifically intelligible.

VViewed in this way, APS is more than a collection of individual concepts or theoretical claims. It can also be understood as a research programme concerned with rendering biological phenomena scientifically intelligible through processes of naturalisation and conceptual stabilisation. The framework repeatedly encounters concepts that are scientifically important yet conceptually unstable, reconstructs them as features of living organisation, and seeks to integrate them within a coherent explanatory structure. The resulting pattern appears across multiple domains of the framework and provides a useful perspective on its overall development.

The progression begins with life itself. APS approaches life not as a collection of static properties but as a process of viability-oriented organised persistence. This reconstruction seeks to move beyond longstanding disputes concerning necessary and sufficient definitions by grounding life in the dynamic maintenance of organised systems. Once life is understood in these terms, agency becomes a natural next question. Living systems do not merely persist; they actively regulate and coordinate interactions that contribute to continued viability. Agency is therefore reconstructed as a feature of living organisation rather than as an exclusively human capacity.

Purpose emerges from this same organisational context. Organisms appear directed toward maintaining themselves under changing conditions, yet such directedness need not imply conscious intention or external design. APS therefore naturalises purpose as an expression of viability-oriented organisation. Cognition extends this trajectory further. Living systems must discriminate among environmental conditions, integrate information, and modify behaviour in ways that support persistence. Cognition becomes intelligible as adaptive information processing and evaluative coordination rather than as a phenomenon restricted to nervous systems.

Meaning follows from the relationship between organisms and the conditions that affect their viability. Environmental signals, resources, threats, and opportunities matter differently depending on their consequences for the organism. Meaning therefore emerges as biological significance rather than as a phenomenon dependent upon language or symbolic thought. From this foundation, the framework proceeds toward increasingly integrated forms of organisation associated with mind, selfhood, and reflective agency. Each stage builds upon concepts developed earlier while introducing new forms of complexity and integration.

This progression should not be understood as a rigid hierarchy or predetermined sequence. APS does not propose that higher-order concepts can simply be derived from lower-order ones. Rather, the framework suggests that increasingly complex phenomena become intelligible through a process of progressive conceptual development. Later concepts retain connections to earlier ones while introducing new organisational features that require additional explanatory work.

Seen from this perspective, APS appears to exhibit two complementary forms of structure. The first is ontological. The framework explains living systems through the interacting principles of agency, process, and scale. Agency highlights the active and regulatory character of living systems. Process emphasises the dynamic and ongoing nature of biological organisation. Scale situates these processes within a continuum of spatial and temporal organisation extending from molecular interactions to ecosystems and evolutionary history. Together these principles provide a framework for understanding what living systems are and how they operate. Just as agency, process, and scale organise APS accounts of living systems, naturalisation and conceptual stabilisation appear to organise how the framework develops biological understanding.

Alongside this ontological architecture, a second and more tentative pattern becomes visible. Across multiple domains, APS repeatedly employs processes of naturalisation and conceptual stabilisation to render biological phenomena intelligible. Naturalisation reconstructs difficult concepts as features of living organisation. Conceptual closure stabilises those concepts within broader explanatory structures. Scientific intelligibility emerges as the outcome of these processes. Whether this pattern represents a general feature of scientific understanding or simply a useful way of interpreting the development of APS remains an open question. Nevertheless, it provides a coherent account of how the framework has approached many of its central concepts.

Viewed collectively, these developments suggest that APS is not only constructing concepts but progressively rendering increasingly complex biological phenomena scientifically intelligible.

The significance of this observation lies not in any claim of methodological novelty but in the possibility that biological understanding develops through a recurring interplay between conceptual development and empirical investigation. APS suggests that scientific progress often depends not only on discovering new facts but also on developing concepts capable of integrating those facts into coherent explanations. Viewed in this light, APS can be understood not simply as a framework for organising biological concepts, but as a programme for rendering increasingly complex biological phenomena scientifically intelligible.

The methodological perspective developed throughout this article provides the foundation for the explanatory approach developed elsewhere in APS. Readers wishing to see how these ideas are applied to living systems should continue to How APS Explains Life.

Four Illustrative Case Studies

The role of naturalisation and conceptual closure becomes clearer when examined through specific examples. The following case studies are not intended as comprehensive treatments of the concepts involved. Rather, they illustrate how the same general pattern appears across different areas of the framework.

Purpose has long occupied an ambiguous position within biology. Organisms behave in ways that appear directed toward survival, reproduction, and adaptive persistence, yet explanations invoking purpose have often been viewed with suspicion because of their historical association with design, intention, and final causes. This tension creates conceptual instability. APS addresses the problem by reconstructing purpose as a feature of viability-oriented organisation. Purpose no longer refers to externally imposed ends or conscious intentions but to the organised directedness of living systems as they maintain themselves under changing conditions. Conceptual closure occurs as purpose becomes integrated with agency, adaptation, regulation, and evolution. Once situated within this network of biological concepts, purpose becomes more scientifically intelligible. The phenomenon remains recognisable, but its explanatory role is clarified and stabilised.

Cognition has historically been tied to brains, nervous systems, representation, and conscious thought. This association has generated persistent controversy concerning the cognitive status of organisms lacking nervous systems. APS naturalises cognition by focusing on adaptive information processing, evaluation, and behavioural coordination. The emphasis shifts from particular biological structures to functional processes that support viability. Closure emerges as cognition becomes integrated with agency, behaviour, learning, memory-like processes, and environmental responsiveness. This integration does not eliminate distinctions among different forms of cognition, but it provides a more stable conceptual framework within which such distinctions can be explored. As a result, cognition becomes intelligible across a broader range of living systems.

Meaning presents perhaps the most striking example. Traditionally associated with language, symbols, and subjective interpretation, meaning often appears difficult to reconcile with biological explanation. APS approaches the issue by beginning with biological significance. Organisms encounter environmental conditions not as neutral facts but as conditions that support, threaten, or otherwise influence viability. Meaning is therefore reconstructed as significance-for-an-agent. Closure occurs as meaning becomes integrated with evaluation, cognition, behaviour, and agency. Rather than standing apart from biology, meaning becomes embedded within the relationships through which organisms engage with their environments. Scientific intelligibility increases because the concept acquires a clear biological grounding and explanatory role.

Although these examples differ in important respects, they exhibit a common pattern. Each concept begins in a state of relative instability. Each undergoes a process of naturalisation that reconstructs it as a feature of living organisation. Each subsequently acquires greater stability through integration with related concepts and explanatory structures. In each case, the result is not complete explanation but increased intelligibility. The phenomenon becomes more coherent, more scientifically usable, and more amenable to further investigation.

These examples suggest that naturalisation and conceptual closure are not isolated operations but recurring features of how APS approaches biological understanding. They also point beyond the concepts examined here. If purpose, agency, cognition, and meaning can become increasingly intelligible through such processes, then similar questions arise for more complex phenomena such as mind, selfhood, and awareness. The next section explores this possibility by examining how the same conceptual trajectory extends from life toward mind, and how it informs the broader Matter-to-Mind research programme.

From Life to Mind

The examples examined thus far illustrate how APS approaches concepts that have traditionally occupied uncertain positions within biology. Yet the implications of this approach extend beyond purpose, agency, cognition, and meaning. Together, these concepts form part of a broader trajectory running through the framework—a trajectory concerned with increasingly complex forms of biological organisation and increasingly integrated forms of biological understanding.

APS begins with life as a process of viability-oriented organised persistence. From this starting point, agency emerges as the capacity of living systems to regulate and coordinate activities that contribute to continued viability. Purpose follows as the directedness inherent in such organisation. Cognition introduces the capacity to evaluate conditions, process information, and adjust behaviour in ways that support persistence. Meaning arises through the significance that environmental conditions acquire for an agent whose continued existence depends upon successfully navigating its surroundings. These developments, in turn, provide foundations for more integrated phenomena associated with mind, selfhood, and reflective agency.

This progression should not be interpreted as a rigid hierarchy or a sequence of discrete levels. Rather, it represents a conceptual trajectory through which increasingly complex forms of organisation become scientifically intelligible. Each stage builds upon organisational capacities present in earlier stages while introducing new forms of integration and coordination. Agency depends upon living organisation, cognition depends upon agency, meaning depends upon evaluative engagement with the world, and mind depends upon increasingly integrated forms of cognition and significance. Selfhood and reflective agency introduce further dimensions of continuity, self-relation, and symbolic mediation.

Importantly, APS does not claim that this trajectory solves the problem of awareness or consciousness. The framework does not provide a complete explanation of subjective experience, nor does it attempt to reduce consciousness to simpler biological processes. Instead, it approaches these questions indirectly. Throughout this article, the recurring theme has been that scientific understanding often depends upon the development of concepts capable of rendering phenomena intelligible. From this perspective, the challenge is not only to explain awareness but also to establish the conceptual conditions under which awareness can become a scientifically tractable topic.

The Matter-to-Mind programme emerges from this recognition. Rather than beginning with consciousness itself, it investigates a series of related concepts that appear necessary for understanding how awareness might arise within living systems. Significance, evaluation, cognition, mind, and selfhood each address aspects of the organisational context within which awareness is experienced and expressed. The aim is not to postpone difficult questions indefinitely but to ensure that the concepts required to approach them possess sufficient clarity and stability.

This strategy reflects the broader methodological orientation of APS. Complex phenomena rarely become intelligible all at once. Understanding often develops through a sequence of conceptual advances that progressively clarify the relationships among different aspects of a problem. The concepts explored in the Matter-to-Mind programme can therefore be viewed as preparatory in a constructive sense. They contribute to the development of an explanatory landscape within which questions about awareness may eventually be addressed more productively.

Whether awareness itself can ultimately be naturalised and conceptually stabilised remains an open question. APS offers no guarantee that this will occur. What it does suggest is that progress is more likely when difficult phenomena are approached through the gradual development of concepts capable of relating them to broader patterns of biological organisation. In this respect, the Matter-to-Mind programme extends rather than departs from the methodological approach described throughout this article.

The broader dependency architecture linking life, agency, biological evaluation, significance, integration, cognition, mind, selfhood, reflective agency, and meaning is developed in The Core Structure of APS, which provides the canonical account of how these concepts fit together within the wider framework.

Scientific Intelligibility and the Future of Biology

The argument developed so far suggests a broader perspective on biological understanding. Scientific inquiry is often associated with observation, experimentation, and explanation. These activities are indispensable. Yet the discussion of purpose, agency, cognition, meaning, and related concepts indicates that scientific progress also depends upon the development of concepts capable of organising what is observed and explained. Difficult phenomena become scientifically useful objects of inquiry only when they acquire sufficiently stable conceptual forms.

Within APS, this process can be understood through the complementary roles of naturalisation and conceptual closure. Naturalisation forms concepts by reconstructing problematic phenomena as features of organised living systems. Conceptual closure stabilises those concepts by integrating them into coherent explanatory structures. Scientific intelligibility emerges through the interaction of these processes. A phenomenon becomes scientifically intelligible when it can be consistently identified, related to other concepts, and incorporated into explanatory practice.

Scientific intelligibility should not be confused with complete explanation. The two are related but distinct. A concept may become intelligible long before every aspect of the corresponding phenomenon is understood. Biological evolution, for example, became scientifically intelligible through the development of concepts such as variation, inheritance, and natural selection, even though many of the underlying mechanisms remained unknown. Similarly, contemporary biology possesses increasingly sophisticated understandings of cognition, development, and ecological organisation despite continuing debates regarding many details. Intelligibility creates the conditions under which explanation can advance; it does not imply that explanation is complete.

This distinction has important implications for understanding scientific progress. Progress is often measured in terms of accumulating empirical data or refining explanatory models. These developments are undoubtedly important. However, the history of science also suggests that progress frequently involves the stabilisation of concepts themselves. Concepts that initially appear ambiguous, controversial, or theoretically problematic gradually acquire clearer explanatory roles and stronger connections to neighbouring ideas. In some cases, persistent debates may reflect incomplete conceptual closure as much as empirical uncertainty.

Viewed in this light, some of biology’s most enduring controversies appear in a different form. Questions concerning agency, information, function, cognition, or consciousness may persist not simply because evidence is lacking but because the relevant concepts remain only partially stabilised. New observations can enrich understanding, but their significance often depends upon the conceptual frameworks within which they are interpreted. Scientific understanding therefore develops through a continual interaction between empirical investigation and conceptual refinement.

This perspective also sheds light on the broader structure of APS. Throughout the framework, agency, process, and scale function as organising principles for understanding living systems. Together they provide an account of how biological organisation is structured and maintained across different spatial and temporal contexts. These principles form what might be described as the ontological architecture of the framework: they concern the character of living systems themselves.

Alongside this ontological architecture, a second pattern appears to emerge. Across multiple domains, APS repeatedly naturalises difficult concepts, stabilises them through conceptual integration, and thereby increases their intelligibility. Naturalisation, conceptual closure, and scientific intelligibility may therefore constitute an epistemological architecture complementary to the framework’s ontological commitments. This interpretation remains tentative and requires further exploration. Nevertheless, it offers a coherent way of understanding how APS approaches many of its central problems.

Whether this pattern reflects a general feature of biological understanding or merely a useful interpretation of APS remains to be determined. The present argument does not depend upon a strong claim of novelty. Its more modest suggestion is that the development of scientific understanding often involves identifiable processes of concept formation and concept stabilisation. APS makes these processes explicit and places them at the centre of its approach to difficult biological phenomena.

Conclusion

Biology relies upon concepts such as purpose, agency, cognition, meaning, and mind because they capture important aspects of living systems. Yet these concepts have often remained controversial, not because the phenomena themselves are absent, but because their scientific status has been uncertain. The persistence of such debates suggests that biological understanding depends upon more than empirical evidence alone. It also depends upon the development of concepts capable of organising, relating, and explaining what is observed.

This article has argued that APS approaches this challenge through two complementary processes: naturalisation and conceptual closure. Naturalisation reconstructs difficult concepts as features of organised living systems, allowing them to participate in scientific explanation without being reduced away or treated as metaphysical exceptions. Conceptual closure stabilises those concepts within broader explanatory structures, enabling them to function more effectively as objects of inquiry. Together these processes contribute to scientific intelligibility.

The resulting perspective reframes the role of APS within theoretical biology. Rather than functioning solely as a framework for describing life, APS can also be understood as a programme for rendering life scientifically intelligible. Its treatment of life, agency, purpose, cognition, meaning, mind, and related concepts reflects a recurring effort to develop concepts capable of integrating empirical findings into coherent explanatory structures. In this sense, the framework is concerned not only with what living systems are, but also with how biological understanding develops.

This interpretation remains open to refinement and revision. Concepts continue to evolve, and scientific understanding remains an ongoing process. Nevertheless, recognising the roles of naturalisation and conceptual closure provides a useful perspective on how difficult biological phenomena become tractable objects of investigation. It also offers a methodological foundation for future work within the APS programme.

The challenges associated with mind, selfhood, awareness, and reflective agency remain among the most demanding in contemporary science. APS does not claim to have resolved these questions. It does suggest, however, that progress is likely to depend upon the continued development of concepts capable of rendering such phenomena increasingly intelligible. The broader Matter-to-Mind programme can therefore be understood as a continuation of the same project explored throughout this article: the effort to render increasingly complex dimensions of life scientifically intelligible, from organised persistence and agency to meaning, mind, selfhood, and awareness.