The Philosophy of Adaptivity

At the core of life is adaptivity, the organismal process of adjusting to ever-changing conditions. But despite its centrality, adaptivity is a surprisingly lonely concept. Its most immediate lexical relatives are parts of entirely distinct evolutionary conversations: ‘adapting’ immediately evokes thoughts of natural selection, ‘adaptive’ (typically paired with ‘maladaptive’) is used in normative evaluations of evolutionary fit, and ‘adaptation’ is more commonly understood as an evolved product, rather than an ongoing process. This linguistic ambiguity makes it difficult to discuss the unique set of questions provoked by adaptivity: What gets adapted to what? What norms guide the adaptation? Which phenomena count as adapting? Perhaps because of how ambiguous and open to misinterpretation these questions are, adaptivity is given little attention by the philosophical community. But answering them would help us uncover our implicit pre-theoretical assumptions about life. My favourite unmasking questions is: is life or cognition possible without adaptivity?

Conceptual issues surrounding adaptivity are fundamental to our understanding of life and mind. However, they do not fit neatly into an evolutionary discourse and cannot be that easily resolved by appeals to natural selection. When asking about adaptivity, we are interested in the incredibly rich array of adaptive capacities that organisms universally exhibit through their diverse ways of living. Therefore, we require a distinct approach, a new conversation, so to speak, with its own programmatic structure and a clear division of labour. I would like to call this new approach ‘the philosophy of adaptivity’ and in the rest of the blog post broadly outline its subject matter and relation to the traditional domains, like the philosophy of mind or biology.

Finding a philosophical home for adaptivity

Let us start with the latter topic. The concept of adaptivity is tightly tied to the study of life and the study of cognition. It is quite common to stumble upon claims that adaptivity is a core characteristic of life (e.g., Barandiaran and Moreno 2008; Koshland 2002; Smith 2018) and that there can be no cognition without adaptivity (Di Paolo 2005; Parr, Pezzulo, and Friston 2022; Thompson 2007). The combination of the assertions that life entails adaptivity and that adaptivity is a prerequisite for cognition places adaptivity right at the heart of the mind-body problem. The role of adaptivity as a ‘missing link’ is especially visible in a family of philosophical views advocating for a strong life-mind continuity thesis. It is a view that the same basic set of principles underlies both life and cognition and can be summarised by two quips: “Mind is literally life-like” (Godfrey-Smith 1994, p. 320) and “Where there is life, there is mind” (Thompson 2007, p. ix). So, while the notion of adaptivity is used as an interface between the biological and cognitive aspects of organisms, the independent task of the philosophy of adaptivity is to give substance to this claim, so that adaptivity does not become a new ‘pineal gland’ of the arguably post-Cartesian integral philosophy.

We can organise the investigation of adaptivity around three key conceptual issues, that I call the “three puzzles of adaptivity”. Inspired by Barandiaran and Moreno’s 2008 paper on organisational aspects of adaptivity, these puzzles challenge a modeller of adaptivity to justify their attribution of identity, norms and the scope of application. They can be summarised in three questions: Who gets adapted to what? What norms guide adjustments? Which phenomena fall under the scope of adaptivity? These puzzles concern the non-arbitrary criteria for the attribution of identity and normativity and for the delineation of the scope of application. Formulating these problems provides a benchmark against which models of adaptivity can be scored.

What is adaptivity?

But perhaps the task for the philosophy of adaptivity is to define adaptivity. To the first approximation, adaptivity belongs together with biological functions, like respiration or photosynthesis, that can only be seen at work in living systems (Lyon 2020), rather than with abstract cybernetic properties, like control, homeostasis or regulation. Many things can be described as if they adapted, such as rivers which adapt their flow or thermostats which adapt to the changing temperature. But these are merely metaphors for various covariations. Barandarian and Moreno (2008) call them “structural adjustments” but even here we should be wary of the dangerous circularity that appears when the line between normative and positive dimensions gets blurry. “Adjustment” or “perturbation” imply that there is a norm, a typical way in which something happens that gets disrupted and has to be adjusted back to its usual state. These normative terms are attributed to a flow of matter which is meaningless without a subject with normativity that should function is a certain way. Perhaps it is safer, then, to define “adaptivity” as a capacity that a living system displays when it changes its internal and external activities in response to or in anticipation of change. Here “change” as a noun means unstoppable large-scale material transfers and energy flows that introduce differences in the material fabric of the universe. Of course, what counts as inside/outside or before/after the change may also be seen as arbitrary but at least we keep the definition without a single, positive (and not normative) dimension.

If we see change as a category encompassing all kinds of material and energy flows, then adaptivity is, in this context, a capacity to limit the flows and be exposed only to a narrow subset of change that is compatible with continued existence. To count as adaptivity, this constraining should be actively achieved through self-generated activity. Passive structural constraints such as barriers, funnels, or redundancies should be better seen as robustness, but not yet adaptivity. So what is it that marks the boundary between non-adaptive and adaptive systems? My suggested answer is metabolism.

Reappraising metabolism as the root of adaptivity

Following Hans Jonas, we can think of metabolism as a special mode of material being which is inherently dialectical. Metabolism can preserve its identity only if it never remains materially the same. Jonas characterised this situation as a manifestation of needful freedom: metabolising systems are free to change their material composition and at the same time they need to do it if they are to continue being themselves. Metabolism must keep on going but its existence is under a constant threat. This possibility of a non-existence imposes a condition that metabolism’s activity must be selective and geared towards avoiding this danger. Metabolic want has specific satisfaction criteria that point outside the boundary of an adaptive system and into the future. The resulting selective horizon is shaped by the concrete metabolic needs and comprises a landscape of metabolically relevant relations, each characterised by their specificness and urgency. Not every currently available option is viable for self-continuation. Therefore, adaptivity needs to be selective. And for adaptivity to be consistently beneficial, the selections are subject to constant subjective revisions with respect to the satiation (or a failure) of satisfying the metabolic need. Thus, the metabolic need that points outwards to the environment must also point inwards towards some sort of internal evaluation.

With the advent of selectivity, it becomes rational for the first time to ask about motivating states, like desires, preferences or in general something that promotes action. It is not reasonable to talk about motivations of physical particles. They cannot help but do what they do in accordance with mechanical laws. However, for adaptive systems there is no such law-like necessity: so what makes adaptive systems adapt? To Jonas, metabolism entails a concernful perspective on the world and as a particular mode of being existing precariously on borrowed time, it strives for existence and avoids non-existence. This claim may seem as a teleological interpretation of metabolism but I consider it to be an implication of the analysis of its definition. Existentially indifferent or purposeless metabolism is a paradoxical concept. This lack of concern is evident in artificially created systems: robots or computers do not strive to stay switched on, also human-like software, such as ChatGPT, does not really oppose to being shut off. Perhaps a way to make artificial systems truly adaptive is to equip them with self-concern for existence. Imagine chatbots’ answers to your prompts if their life depended on it! While injecting existential dread into an artefact is just a wild thought, the inverse – exploiting the existential drive of living cells for engineering solutions (aka biological robots or xenobots), has been a very fruitful line of research (Blackiston et al. 2024).

So far I have been speaking about Jonas exclusively in superlatives. Through his analysis of metabolism, Jonas identified several defining features adaptivity, such as sensitivity, selectivity or anticipation. However, he did not try to ground them organisationally in metabolism. Instead, he inferred that adaptivity entails an inward identity – a self that senses, selects and anticipates adaptations. Unfortunately, when viewed through a contemporary “naturalist” lens, Jonas’ method of phenomenological inference and transcendental arguments for what adaptivity requires may be seen as “unscientific”. This led some to reject Jonas’ account of metabolism in totality, without realising the conceptual analysis is makes an independent argument and does not rely on the “unscientific” phenomenological inference (Prokop 2022). Scientific-methodological naturalists instead chose to demonstrate life-mind continuity using a contemporary theory of minimal living organisation: the autopoietic theory. Metabolism got replaced by autopoiesis – an abstract organisation that we still cannot fully engineer (Stano and Damiano 2023) – and the new argument has been going on since whether it can provide the necessary grounding for life and cognition. My proposal puts back metabolism as a naturalising phenomenon that answers the fundamental puzzle of adaptivity: who adapts to what, and what norms guide the adjustment? When the scope of adaptivity is metabolism, identity becomes a metabolic identity, and normativity is grounded in metabolic want. This solution provides us with a fresh start to the scientific study of adaptivity.

The diachronic origins of adaptivity

By revisiting metabolism, we are also in a more natural position to address an issue that has, to my knowledge, not been addressed in philosophy of cognitive science at all—namely, the origin of adaptivity. The diachronic perspective of how adaptivity appeared at some point in time is missing, even though it has an incredible potential to inform us about the conceptual issues surrounding the definitions of life and cognition.

The natural world changes fast and those that cannot keep up, quickly perish. Living without adapting is currently not possible. At least not for long. Consequently, the ‘should adapt’ is simultaneously a ‘must adapt’ for life to continue to exist. But maybe it was not always like that. By this I mean that it is not impossible to conceive of life without adaptivity (which perhaps we should call proto-metabolism, if metabolism entails adaptivity). If self-(re)producing systems were to exist in extremely favourable conditions, with the exactly right energy transfers and material flows and without ever encountering any perturbations or dangers, then there would simply be no need for adaptivity.

This idyllic situation is not just a pure conceptual possibility but may have taken place at the origin of life, where the first forms of metabolism emerged in relatively stable and spontaneously cyclical environments, such as the gentle cradling during day-night cycles in a shallow sea (Runnels et al. 2018). This is, of course, just a speculation, but just imagine that the most basic cycle of life – the Krebs cycle – could be an accidental product of billions of cycles of ebbs and flows, days and nights, convection and sinking… in a shallow sea.

Conclusion: the joy of talking adaptivity

Adaptivity is exciting to think and talk about. And it is philosophically relevant. I hope to popularise ‘adaptivity’ as a distinct term in philosophy. Its immediate connotation should be the adjustment of activities rather than adaptation through natural selection. The label “adaptive” should be seen as an instantiation of a self-centred active capacity as opposed to a passive property of being changeable or adjustable. Genuine adaptivity is a biological phenomenon, as real and non-mysterious as respiration or digestion, and it is all around us. Understanding it as a capacity is not just an exercise in analytic philosophy but has practical benefits: we aim to push the limits of biological adaptivity in the face of climate catastrophe. We are also striving to emulate adaptivity in robot helpers and AI, so that they can flexibly respond to our constantly evolving needs. Finally, thematising adaptivity is an incredibly gracious exercise that can quickly turn profoundly existential and bring philosophising back to facing reality courageously and head-on, not being a reply to a reply. The question “why life adapts?” touches directly on the rationale for the existence of life in the world and the mind in life. My suggestion is to engage in this thought process with the aid of a structured and interdisciplinary programme—a philosophy of adaptivity that, betwixt the philosophy of life and the philosophy of mind, carves its own niche.

References

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