The focus of our investigation here has always been on biological aging. In our recursive definition attempt the main suggestion is that out of the irreducible plurality of diverse but interconnected biological aging processes operating on the molecular, cellular and other sub-organismal levels, organismal, individual level biological aging can be understood and interventions can be designed against it.
But we need a step back here and acknowledge a more fundamental irreducible plurality of the aging concept, a sort of global version of the local plurality of biological aging , namely that the default aging concept has been used in several different meanings already. This global plurality comes first as aging usually presents itself in different variants depending on the domain we are talking about it.
We can talk about aging of living things but we can also talk about aging of non-living objects, natural (planets, rivers) or human-made (cars, houses, pipes).
Within living, biological organisms we usually talk about species level specific aging, out of which human aging is our default version, not surprisingly.
Within human or human-related aging we have many versions, some of them I captured in the figure below, and biological aging, the one with medical consequences is only one of them.
At the core of all aging concepts is chronological aging, the passage of time, that can be registered, measured. Since our mode of existence is temporal (spatiotemporal) everything we do, experience and observe has a temporal aspect, an aspect that gives rise to all of our possible aging concepts.
Some domains or subjects of human activity are relatively atemporal, here a good example is mathematics . Obviously mathematical activity and insights and progress are temporal but not much of this is present at the level of mathematical theorems and proofs. Temporality is hiding in many branches of mathematics, for instant in geometry and topology, focusing on the spatial aspects and properties of objects. Other branches, like dynamics, looking into changes of trajectories over time, have temporality back in focus.
Overall this deep rootedness of temporality is responsible for the confusions we experience and practice when mixing different aging concepts.
Perhaps we can say, that although the plurality of aging is unavoidable but it is not necessarily irreducible. For we can reduce all talks on agings to chronological aging, our primary understanding of aging, the dimension that gives rise to every other agings we talk. But then what do we mean by ‘reducibility’ exactly? And what’s left to discuss once this reduction has been completed?
It is true that all kinds of aging concepts we have are intimately related to chronological time and chronological aging, which registers the passage of time. But having its origin in chronological time, or rather to say, having chronological time as a necessary condition of all other agings we’d like to understand provides everything, but an explanation for these diverse aging concepts. I’ve already talked about how little temporal causation helps with adding extra explanatory power to understanding biological aging in The rabbit hole of temporal causation and biological aging. Another question we could ask here whether behind the different aging concepts, say biological aging and psychological aging are there any strict structural patterns so one, say the more advanced one, can serve, via analogy, to research the other, to provide methodological tools or content insights? Does biological or psychological aging follows a step function or a linear one, perhaps we do have consensus working definitions in these fields signalling an almost complete understanding that come and rescue the more immature field? The answer is, for the time being, is a big NO. Even if this were the case, it would not come for a successful reduction to all these phenomena to chronological time and chronological aging.
I conclude that chronological aging does not have an illuminating reductive power over other aging concepts. It is not enough to point out its necessary role behind other aging concepts and if there are structural correspondences between some of those concepts, it is not the success of reducing them to chronological time’s passing. The same dynamic mathematical models, simulations and forecasts can work over different domains, tracking different trajectories but this does not equal to an epistemologically successful reduction to chronological aging in any sense.
At this point I feel a little like Don Quixote tilting at the windmills.
I’d like to finish by acknowledging the irreducible plurality of the aging concept and suggest to use agings instead, when applicable. In the concept of ‘aging’ we have a chimera with an underlying link, a current.
This irreducible plurality is not vagueness in the sense of ambiguity or underspecificity or indeterminacy. I would need to think hard to come up with a good argument of a Sorites Paradox-like vagueness in case of biological aging say, when it might be argued that the temporal stage of applying the term ‘aging’ lacks a sharp boundary between cases when it can definitely be applied and cases when it cannot. Will go back to this at another time, but let’s do some aging first.