Gaia as Seen from Within

Abstract

Through our three-way collaboration we sought to understand Gaia and its political implications from the bottom-up and from within. Here we introduce that view of Gaia and how the dialogue between a philosopher (Bruno), a scientist (Tim), and a historian and philosopher of science (Séb) turned into a research programme. This sets in context a previously unpublished piece by Latour: ‘There is nothing simple in a feedback loop – or why goal function is not the problem of Gaia’.

Introduction

The importance of the climate issue goes almost without saying. At the time of writing (June 2024), global temperatures have remained persistently 1.5°C above the pre-industrial level for over 12 months. Experts remain baffled by the extremity and persistence of this temperature anomaly, which is much more than that expected from an El Niño event on top of global warming. As Bruno Latour would put it, the climate is clearly ‘out of whack’ and surprising us in non-linear ways (Latour, 2017a). That in turn reveals that our default expectation is of a stable climate that is somehow regulated. James Lovelock, in collaboration with Dian Hitchcock and later Lynn Margulis, famously postulated that life is involved in regulating the composition of the Earth’s atmosphere and thus the climate, in what became known as the Gaia hypothesis (Hitchcock and Lovelock, 1967; Lovelock, 1972; Lovelock and Margulis, 1974a, 1974b; Margulis and Lovelock, 1974).

In their efforts to explain ‘Gaia’, Lovelock and Margulis reached for a raft of cybernetic and biological metaphors. They variously described the ‘homeostasis’ or ‘self-regulation’ of atmospheric composition and began to sketch the feedback loops that might be responsible. At different times Lovelock likened Gaia to an organism or to a superorganism, although Margulis clearly recognised that Gaia was not like an organism, because, as she put it: what organism eats its own waste products? The organism metaphor, the mythological name after an Earth goddess, and the language of a ‘self’ that regulates, invited a totalitarian view of Gaia that has misled followers and critics alike (Latour, 2017b). It provided easy fodder for biologists to critique the hypothesis as unworkable in principle.

But Jim Lovelock was always open about his struggles to explain what he had intuited in Gaia. He naturally reached for concepts familiar to him, from his polymath grounding in engineering, chemistry, and medical research (among other disciplines). With his poetic prose he also offered many different entry points to thinking about Gaia. One of Bruno Latour’s favourites was: ‘The Gaia hypothesis implies that the stable state of our planet includes man as part of, or partner in, a very democratic entity’ (Lovelock, 1979). This connects the socio-political dimension of Gaia with the scientific. Unpacking that connection was a key focus of our collaboration.

Two Views of Gaia

Lovelock arrived at Gaia from two very different perspectives (Dutreuil, 2016, 2018). The familiar story is of a top-down approach triggered by his employment by NASA in the search for life on Mars – Lovelock and Hitchcock saw that a general way to detect life on a planet was to look for disequilibrium in its atmosphere (Hitchcock and Lovelock, 1967; Lovelock, 1965). But Lovelock also discovered Gaia from the bottom up, tracing the gaseous emanations of microbes and humans and finding them throughout the global atmosphere (Lovelock, 1971, 1975; Lovelock et al., 1972, 1973). It is this less familiar bottom-up path to Gaia that Bruno Latour favoured to tread.

The two perspectives can be contrasted as the views from outside and from within Gaia. Bruno used to laugh or exclaim whenever one of the famous photographs of the Earth taken from space appeared in a presentation – especially if it was one of Tim’s presentations – because of the false detachment it symbolised. Bruno was fond of pointing out that almost no one has the privilege of that view. Even those very few astronauts who have had the opportunity only had it as a brief and tenuous extension of Gaia’s life-support into space. Instead it is from our position within Gaia that we must work out a new politics appropriate for the new climate regime (Latour, 2017a, 2018).

Bruno also disliked the view of Earth from space because it symbolised the worldview of the ‘Moderns’ – to act as if they are outside and above nature, which is purely there to be in the service of human emancipation. This is why Bruno was so insistent that we get back ‘Down to Earth’ (Latour, 2018) and engage with the other citizens of Gaia from within the critical zone – the thin film of life, air, water, and soils that supports us (Latour and Weibel, 2020).

The matter at hand is nothing short of a shift in worldview. Or as Lovelock put it: ‘From a Gaian viewpoint, all attempts to rationalise a subjugated biosphere with man in charge are as doomed to failure as the similar concept of benevolent colonialism. They all assume that man is the possessor of this planet; if not the owner, then the tenant’ (Lovelock, 1979).

To capture that shift in worldview, we need to shift our viewpoint of the world and engage with Gaia from within, from where we are sat or stood (or running or swimming). One way to do that, which Jim Lovelock and Lynn Margulis pursued, is to trace the consequences of the metabolisms of organisms (including us) and see where they lead. Doing so immediately starts to dissolve the organism-environment and human-nature dualities, as it uncovers the cycling flows of essential elements between living things.

The novelty in what Lovelock and Margulis did was to keep following those flows to the global scale and over 4 billion years. What this reveals is a gloriously messy picture of actors in networks forming mutual interdependencies over a host of space and time scales. All of them are actively engaged in creating and maintaining their own conditions for survival and flourishing. This is as true of the simplest bacterium as it is of the most intelligent octopus (or human). Following the flows of human industrial metabolism, we soon see not just the creation of a new climate regime, but growing antimicrobial resistance, and the jumping of a novel coronavirus into the human population.

This view from within Gaia, and the recognition that we have knocked things out of whack, invites us to renegotiate our relationships with other living things. How we do that is not defined. There is no playbook. We must experiment, get our hands dirty, learn-by-doing. The human and (micro)biological meanings of ‘culture’ need to come together. We might try to form a ‘Parliament of Things’ where the voice of other life forms is represented. We might fight for the legal rights of nature. We might try to learn some lessons in sustainability and flourishing from the rest of Gaia. There is a lot to work on. So, how did we get to work as a trio?

Our Three-Way Dialogue

Séb introduced Tim and Bruno at a workshop he convened in Paris on 24–25 March 2016 on ‘Gaia and Earth System Science: Scientific, Historical, and Philosophical Perspectives’. Bruno had already published Facing Gaia in French and Séb was completing his PhD thesis on the history of Gaia research (Dutreuil, 2016). After 20 years of largely failing to get the scientific community more interested in Gaia, Tim was delighted to meet two kindred spirits and buoyed up by this new injection of energy and interest in his favourite subject, which seized on its philosophical and political implications. On reading the English edition of Facing Gaia, it became clear that we shared a common view.

Tim also got inspired by discussions (walking on a beach) with Exeter colleagues. Although up to now Gaia had emerged unconsciously from all those living beings just doing their thing, some humans seemed to be adding a little self-awareness to the Earth’s self-regulation – at least to the extent that they opted to change behaviour to limit their impact on the climate. We gave this a name: ‘Gaia 2.0’.

Some of this thinking got a try-out at the Cini Dialogue in Venice (13–15 September 2017) on ‘What’s the Body of the Body Politic? Sovereignty, Identity, Ecology’. There we discussed Gaia with Simon Schaffer, Isabelle Stengers, Timothy Mitchell, Shirley Strum, and others. Tim gave an interjection supporting Bruno’s bottom-up view of Gaia as a phenomenon and introduced the idea of ‘Gaia 2.0’. This greatly amused Bruno as he knew full well our poor track record as a species and our over-inflated notions of consciousness. Our shared thinking started to gestate.

Five months later, Bruno and Séb came to Exeter for a workshop (27 February 2018). A rare snowstorm arrived with abundance and Bruno got stuck in Exeter for the first few days of March. This serendipitously gave Tim and Bruno the time to work and write intensively together. Bruno would eat together with Tim’s family, who also provided him with warm clothing, and that brought us all together as friends, like an extended family. We would share ideas then write separately, exchange texts, and meet in a cafe or at the house to discuss further. This climatological interruption allowed a little taste of Parisian intellectual culture in snowy Devon. By the time the thaw came, and flying back to Paris became possible, we had the core of two texts: ‘Gaia 2.0’ and ‘Extending the Domain of Freedom, or Why Gaia is so Hard to Understand’.

Over the next few months, we sent them to journals – Science were surprisingly receptive to the ‘Gaia 2.0’ piece (Lenton and Latour, 2018) – given, as Bruno discovered, that the word ‘Gaia’ had only been mentioned 11 times in article titles in the space of 30 years, almost all of them news pieces. Perhaps they recognised it was timely as out-of-this-world President Trump was busy taking a wrecking ball to our collective capacity to sense Gaia from space. As Bruno stressed, without sensing what is going wrong in Gaia, we cannot possibly correct our mistakes. We viewed ‘Gaia 2.0’ as a provocation that demanded clarifying how Gaia is distinct from the modern view of nature, before attempting to draw further lessons from it for the contemporary situation. Meanwhile, ‘Extending the Domain of Freedom’ was an attempt to start to flesh out how Gaia is distinct from nature and its political implications. Critical Inquiry initially rejected our submission. As Bruno paraphrased their response: ‘come back to us, Bruno, when you have something interesting to say’! We are not sure what caused them to change their tune, but they did (Latour and Lenton, 2019).

Bruno warmly invited the Lenton family to stay in his flat in Paris at the end of July 2018 just as he and Chantal were leaving for a concert tour in Eastern Europe. This was the opposite end of the meteorological spectrum to our time in Exeter, as a heat dome formed over the continent. We met briefly at the flat to pick up the keys on what was Jim Lovelock’s 99th birthday and then proceeded to exchange texts on the severity of the heat in our different parts of Europe. The Lenton clan rather enjoyed the heat in Paris – although it started to create mediaeval smells around the Seine – but the Latours really suffered further east.

That autumn the three of us convened in the flat in Paris (9 October 2018) for the first of several memorable gatherings. We would sit around the table with paper and pens to hand. The collaboration would typically involve Bruno encouraging Tim to explain some Gaia scientific concepts by drawing them out graphically, with Séb setting the science in its historical and philosophical context. Or Tim would be patiently asking Bruno and Séb to explain some complex philosophical concepts they were interjecting. On this occasion Tim was walking through how Lovelock and his few scientific followers have tried to explain how ‘self-regulation’ could come about in the absence of a ‘self’ at the global scale. We got into discussing circular causality – feedback loops, ‘goal functions’, and related concepts that Jim Lovelock had borrowed from cybernetics in his attempts to describe Gaia.

We managed to identify three distinct notions of ‘goal function’, which Bruno summarised in a subsequent memo. Goal function 1 has ‘attractor’ as a synonym and is mostly used to describe physical-chemical systems. Goal function 2 captures one of the properties of the systems in which life forms are involved; the agency of those life forms is detected because they skew the results that would be expected if only physical-chemical relations were at work – for example, in the Daisyworld computer model of climate on a hypothetical world, the global temperature is drawn back towards what is optimal for the daisies (Watson and Lovelock, 1983). Goal function 3 has loose synonyms – ‘purposefulness’, ‘cognition’, ‘consciousness’, ‘teleology’, ‘foresight’ – and describes the situations when a human agent is taking over the task of fixing goals in advance and following up the course of action until completion. As Bruno put it: ‘some clarity would be introduced in the debates if they were made distinct, first by distinguishing 1 and 2, and then resisting the temptation – apparently irresistible in readings of Gaia – to confuse 2 and 3’.

The meeting also inspired Tim to do a brain dump of ideas to begin to express how Gaia represents a new kind of nature. Bruno’s response to those scattered thoughts helped us start to organise a shared research programme, and a plan for a series of papers. Key to this was to first tackle how Gaia represents a new kind of nature before returning to ‘Gaia 2.0’ and drawing any kind of guidance from the Gaia worldview. Amidst a list of six possible outputs, Bruno was keen to see a piece from us on the difference between Gaia and Earth system science, including a clear list of the Gaian effects on Earth history.

At the same time, Bruno began to be perturbed ‘by the physicians intervening in my life and they will keep doing it for a while’. His battle with cancer had begun and that winter he underwent chemotherapy. In Spring 2019 he conveyed the good news that the cancer was in remission, and the three of us arranged to meet again in the flat in Paris at the start of June 2019. There we debated and refined the content of what became ‘Life on Earth Is Hard to Spot’ and planned out a piece on circular causality.

At the end of the following month, we all met again in the UK for Jim Lovelock’s hundredth birthday party, followed by the Lovelock Centenary conference that Tim hosted in Exeter. This was a chance to celebrate as well as intellectualise. There was a particularly memorable open mic session in the cellar rooms of a pub in Exeter where, amidst music and poetry readings, Bruno and Tim performed Bruno’s sketch about the challenges of staging ‘Life of Lovelock’, his reworking of Brecht’s ‘Life of Galileo’.

Afterwards, Tim and Séb worked on a couple of contributions to the Critical Zones volume that Bruno was editing (Lenton and Dutreuil, 2020a, 2020b), with Bruno doing an amazing job of sharpening ‘What exactly is the role of Gaia?’. We also completed ‘Life on Earth is Hard to Spot’, our first attempt to clarify how the Gaia view is distinct from Earth system science, and why different fields have struggled to see it (Lenton et al., 2020). Initially Bruno was reluctant to coauthor but his input was so valuable in shaping it we persuaded him to join.

At the start of December 2019, we met again in Paris, and Bruno seeded our discussions by sending a memo in advance: ‘There is nothing simple in a feedback loop – or why goal function is not the problem of Gaia’. It landed fully formed, as was often the case with Bruno. In the flat together, Tim started riffing off it with some examples of how scientists see Gaian feedback loops having first come about on the early Earth. We were at the time considering adding this into the piece. But instead, we have opted to reproduce Bruno’s original memo below. As he reflected later: ‘the shift in thinking on what is a goal function, why it was wrong to disregard Gaia as having a goal, and what it means today for humans in Gaia to have goals, all of those elements are absolutely crucial politically’ (email to Tim, 19 January 2021).

Soon after gathering in Paris the pandemic struck and Bruno’s battle with cancer resumed. This double interruption stalled our collaboration. As Bruno put it: ‘it is so depressing over here to be without kids, films, restaurants, cafés and friends . . . horrible experience’ (email to Tim, 17 December 2020). ‘I have been sick most of the time, from cancer, from the treatments against it, a paradox I have not yet resolved’ (birthday wishes to Tim and Jim, 25 July 2021). We kept in correspondence, exchanging other pieces we were writing, and Séb got us contributing to the volume of Lovelock-Margulis correspondence he was co-editing (Clarke and Dutreuil, 2022).

When Jim Lovelock died on his 103rd birthday (26 July 2022) it triggered a zoom catch-up together (23 August 2022). Bruno seemed in good health and by the end of September we had a plan to meet up in Paris the following week. After Tim had spoken at a microbiome seminar organised by Eric Bapteste, Séb would join us for a session around the table in the flat. But tragically, by the time Tim set off, Bruno was back in hospital, and the end came quickly.

Bruno’s passionate enthusiasm for inquiry left many of us with ongoing research programmes. ¹ The rest of this paper delineates the one on which we were working together, first by offering a bit of context, then by reproducing Bruno’s previously unpublished draft.

The Teleology Problem

The Gaia debate has been vastly misguided over the past decades by a narrative comprising three ideas: (i) there is a controversy with evolutionary biologists, (ii) bearing on whether Gaia could really be understood as alive or as an organism (‘no, because it does not reproduce’) or on (iii) whether a global altruism was possible (‘no, because there is no theoretical mechanism involving natural selection that could account for it’). None of the three ideas stands further scrutiny: (i) there was no controversy between Gaian and evolutionary biologists (evolutionary biologists simply did not care about Gaia after two critiques in the early 1980s; Dawkins, 1983; Doolittle, 1981); ² (ii) the central Gaian proposition has never been an ontological statement which ought to be evaluated against a list of necessary and sufficient properties for being ‘alive’ or ‘an organism’; (iii) nor has it been an idea of global altruism. ³

So why did evolutionary biologists have such an allergic reaction if, in the end, the scientific topic discussed was foreign to their main interest? Because of the teleological phrasing of Gaia: Lovelock and Margulis sought for the functions of the myriad of activities of living beings at the surface of the Earth – what were they all doing for the maintenance of Earth’s habitability? The problem was thus philosophical and not really theoretical. The centrality of this philosophical issue has been stated very clearly by Richard Dawkins in a documentary:

The danger is that they will say things like ‘the function of oxygen is . . .’, ‘the function of ammonia is . . .’, ‘the function of methane is . . .’, and where ‘is’ is followed by some regulatory purpose, something for the good of the biosphere. Now, don’t get me wrong: I’m not saying that I’m objecting to that kind of purposeful language. At the level of the individual organism, I’m quite happy to say ‘the function of the bird’s wing is to keep the bird up’; ‘the function of the bird’s eye is to form a well-focused image’. I’m quite happy with that purposeful language because that is at the right level in the hierarchy of life. What I’m not happy about is to talk about the function of a particular gas in the regulation of the biosphere because it implies that individual organisms that are manufacturing that gas are doing it for the good of the biosphere. It further implies that if it were bad for them as individuals, they might still do it because that is the only way the biosphere will persist. The real danger is that people will think, will assume, that individual organisms will sacrifice themselves for the benefit of the entire system. And that’s wrong. And it’s dangerously wrong in the sense that it is fairly widely believed among laymen and even among professionals. ⁴

At that time, Dawkins was indeed right to point out that there was an issue. Ever since the 19th century we have lived in a world where it was philosophically sound to attribute functions to two kinds of entities, and these two only: artefacts (because they were produced for a purpose, defined by the intention of the engineer); and organisms (because they were thought about along the lines of an analogy with the machines designed by an engineer; or, to use a later framing, because they undergo natural selection, and the historical effect of natural selection somehow replaces the action of the engineer, ultimately grounding the intuition that it is sound to say that it is ‘the function of the heart to pump blood’). In this modern world, contrary to what was the case in the Aristotelian cosmos, it is philosophically strange if not impossible to attribute a function (or a telos) to a rock or a river. Gaia seemed to extend the list of entities to which we could attribute a function or a role (although not to strictly abiotic entities: it is always focused on the activities of living entities that ultimately modify abiotic conditions). And Lovelock and Margulis were perfectly aware that there was something new to be reflected upon here, long before evolutionary biologists reacted:

If we assume the Gaia hypothesis, and regard the atmosphere as a contrivance, then it is reasonable to ask what is the function of its various component gases. Outside the Gaia hypothesis, such a question would rightly be condemned as circular and illogical but in its context such questions are no more unreasonable than asking, for example, what is the function of fibrinogen in blood. (Lovelock and Margulis, 1974a: 5)

Lovelock’s private correspondence also illustrates that Lovelock was struggling with these issues at the very beginning of the formulation of Gaia:

How can one describe a multiple system of closed loops all interdependent and self regulating without using circular arguments??? I wish that I were a Professor of Teleology, it would be easier then. (Lovelock’s letter to James P. Lodge, 9 December 1970)

So, the ‘teleological’ issue was pointed out: something seemed at odds. But has there been any attempt to deal seriously with it (and not just to dismiss it right away, as Dawkins did)?

Different Ways of Thinking about Functions

Gaia brings to the fore issues which were foundational for the way we currently think about functions. At the dawn of the 19th century, the tripartition between mineral, plants and animals organising natural history gave way to a new ontological partition – a bipartition between living and non-living entities – and a new division of knowledge: metaphysics was separated from the ‘sciences’, and natural history was replaced by biology, geology, and the other branches of natural sciences. At that time, biology was constituted in the wake of new philosophical reflections on the status of organisms and on ‘natural purpose’ by Immanuel Kant (Huneman, 2007, 2008). Both the very nature of these linked issues and the longue durée of the philosophical reflection must be kept in mind when discussing Gaia’s teleology. Gaia seemed to upset a series of issues established two centuries ago: the divide between living and non-living, the list of entities with a purpose/function, the organisation of knowledge (think about the Gaian claims for interdisciplinarity and a return to natural history), the importance of the philosophical and sometimes metaphysical dimension of the sciences, etc.

Interestingly, the 1970s and the 1980s is exactly the period during which we saw a growing literature at the intersection of philosophy of science, philosophy of language and philosophy of biology on the very question of function and teleology. Roughly two traditions emerged:

A first tradition, usually labelled ‘etiological’, has tried to justify and naturalize the teleological dimension of functions by appealing to a scientifically acceptable causal explanation. In the mainstream formulation, etiological approaches appeal to a historical-selective causal process, through which the existence of current functional traits is the consequence of the selection exerted on the effects of previous occurrences of the trait. A second tradition, called ‘systemic’ or ‘dispositional’, discards the teleological dimension of functional attributions as a relevant explanandum by interpreting functions as causal means–end relations at work in a system. (Mossio et al., 2009)

A third tradition, the organisational account, developed in the late 2000s, inheriting from a tradition of thought centred on the ‘auto-organisation’ of organisms, going from Kant to contemporary autopoiesis (Mossio et al., 2009). Contrary to the systemic tradition, the organisational account aims at retaining the normative dimensions of functions. ⁵

Until very recently, there has never been any attempt to deal seriously with the issue and to confront Gaian examples with any of these philosophical accounts of function (Babcock, 2023; Nunes-Neto et al., 2014). This may not come as a surprise: philosophy of biology is a community very close to that of evolutionary biologists, with no interest whatsoever in Gaia. Besides, the analytical stance adopted in the literature on functions and teleology somehow impinged on openness to new possibilities: in this literature, the methodology that prevails presupposes that we already know which entities can bear functional statements (organisms, artefacts); the only difficulty that remains is to give ‘the best account’ of function which adequately seizes these entities and not other ones. Nonetheless, it would have been possible to play the little game of confronting Gaia with each of these three accounts of functions, e.g. to draw empirical examples from the Gaian literature and see whether they fit these accounts. ⁶

This is not the line we followed together, perhaps due to the oddity of our gathering and complementarities. Tim, an Earth scientist, inherited from Lovelock the strong intuition that Gaian phenomena were at the same time ‘real’ and at odds with the current scientific and philosophical worldview underpinning the modern understanding of the natural word; Sébastien, who was trained both in the Earth sciences and in the analytical philosophical tradition underpinning the three accounts of functions, was convinced in the early 2010s that the ‘little game’ confronting Gaia with these traditions would have no consequences (not for the lack of analytical results, but out of the sheer sociology of the communities involved ⁷ ); and Bruno defended a philosophy at odds with the modernity understanding on the major concepts at play: agency, intention, causality, individual, hindering the very possibility of a dialogue with any of the existing traditions on function. Both the state of the discussion in the literature, the complexity of the debate itself, and the heterogeneity of our small group did not help to make progress. The last attempt was Bruno’s draft trying to start the discussion again. We reproduce it here, with the hope that it may open some lines of reflection on an unfinished project.

There Is Nothing Simple in a Feedback Loop – Or Why Goal Function is not the Problem of Gaia

(Bruno Latour’s memo for a meeting of the three of us on 2 December 2019)

Because it has been recently put out of whack, there is now a strong public awareness that the Earth climate obeys some sort of self-regulation. This is why geopolitical negotiations are so anxious not to pass the threshold of 2°C for its overall temperature. The notions of threshold, tipping points, deep history, are now common themes of conversation. However, there is a complete obscurity on the historical origin as well as on the exact mechanism of such a ‘self-regulation’. What is this ‘self’ and how does it ‘regulate’ itself? Around which ‘set points’? Who has discovered such machinery and what sort of confidence can we have in it? All those questions are in no way part of the public discourse. There is nothing self-evident in the idea that the Earth self-regulates itself because it pursues some goal of its own. Hence the interest in clarifying this question.

In a recent paper, we have shown that it’s because life is hard to spot on Earth that the discovery of a self-regulated Gaia, in spite of its relevance to the present discussion, has been almost immediately lost. No matter if it has been accepted enthusiastically or rejected out of hand, it was in both cases for the wrong reasons, or rather, due to insufficient attention to the originality of the phenomenon that the ‘Gaia hypothesis’ introduced by Lovelock and later Margulis had tried to capture. Gaia is a sui generis phenomenon in the literal meaning of the Latin expression: it generated itself in a fashion so idiosyncratic that in order to define its function it would have been better to rework many conventional concepts used by several disciplines: Earth system science, geology, biology, ecology, social theory and even political philosophy. Naturally, in the 1960s, its inventors had no time to clarify the meaning of the notions they took off the shelf, busy as they were to pinpoint the novelty of their object. Hence, the overuse of metaphors and half-baked concepts borrowed from cybernetics, medicine, geology, biology and politics fit for very different usages. It is only today, because of the shock of the Anthropocene, that it becomes urgent to clarify what exactly is the state of affairs called Gaia, inside which humans have interfered so widely and apparently so wildly.

To make sense of Gaia, it is best to choose another point of departure than the one suggested by common sense: that is, to not focus on an organism, usually an animal, or a plant, and then to situate it inside a material context that defines its ‘environment’, in order, then, to follow their interactions. Instead it is better to start with some metabolic activity and follow how it transforms its inputs into some more activity generating, in turn, some other modified products entering into some further metabolism down the chain. The difference between the two starting points is that, in the first one, a divide is introduced between following what happens to the organism and what happens to its environment, as if they were situated on two parallel lines with only a few interferences. While in the second point of view, we start with what becomes at once a cascade of metabolic transformations, the output of one segment, being the input of the other, without any a priori difference between ‘organism’ and ‘environment’. ⁸

With the first starting point, the question is: ‘Do you study the inside of organisms or do you prefer to study their outside material environment?’, while if you choose the second, the question becomes: ‘How far and how long are you ready to follow the metabolic cascades?’ The first one launches the disciplines of biology or ecology centered on the organisms, a focus that keeps them, by necessity, quite apart from geology and physical geography centered on the Earth system. The second starting point defines what could be called a Gaian way – still not easily registered in any disciplinary framework.

Let’s see how things go when you choose the second point of departure. In terms of activity, a metabolism has an upstream, a midstream and a downstream component. Upstream, it receives the outpour of other entities, which affects it for the good or for the bad; downstream, it lets go all the output and dejection of its metabolic activity; in the middle resides the changes it operates, hence the name ‘metabolic’. What is of interest to us, however, at this point, is not the chemical pathways, but how long and how far do we follow the cascade upstream or downstream. Downstream, the entity gives away something; upstream, it receives something.

At this point we might be able to witness three ideal situations: as far as the observer can tell, there is no connection between what leaves the entity chosen as the point of departure and what enters it; or there is a possible connection, in which case we can say that there is a coupling between the two, but it remains a loose coupling; or, a third case, in which there is a quick, sharp and short connection, in which case we say that there is a tight coupling.

In all that follows we should remember that ‘coupling’ is not to be taken as one circle or one cycle, but, as the etymology reminds us, as something made of two elements that might have been joined or not. The couplings we are going to consider are, like all couples, submitted to many crises. . . . Thus, we should beware of the temptation to simplify the coupling of separate and distinct elements by tracing a circle on top of them as in so many drawings of feedback and chemical cycles (more on this later). Coupling is a risky undertaking more comparable to artists throwing themselves off a trapeze – and expecting their partner to seize their hands in time.

We may already offer a rough distribution for those three cases. First, the default position: most metabolic activities chosen as the point of departure let waste and output get out without any possibility of tracing whether it gets back or not to feed the activity once again; they are like messages put in a bottle and thrown into the sea. Second, there are some rarer cases where the activity of one entity might result in something coming back in the form of an input, the path of this return ride being more or less traceable but with lots of holes and discontinuities in between. Third, there are even rarer cases where the coupling is so tight and so quick that an almost direct connection can be traced between what gets out and what is fed back in. This is what happens within what are called ‘organisms’ – cells or plants or animals – and it is even simpler to detect in man-made mechanisms when the expression ‘this part is made for acting on this other part’ is perfectly straightforward (the same is visible even more vividly for trapeze artists!).

We now understand that it’s because this third case is the rarest that, as stated above, it would have been a mistake to choose as our point of departure the situation of one organism inside an environment. Organisms able to give the impression of a closed loop cannot be taken as the general case – and we should always remember that a couple, even tightly knit, is still a couple made of at least two distinct entities that could at any point be divorced from one another, just like trapeze artists may fail to coordinate their jumps. It is the oddity and the rarity of organisms (especially multicellular ones) and the even more extreme rarity and novelty of human made machinery – both chosen wrongly as the general case – that has rendered so obscure any discussion of how far and how long a metabolic pathway would extend. To resist the central role of organisms, and to resist the idea that they are bounded by a wall that could define a clearly delineated ‘self’, is essential if we want to pursue our description by choosing the metabolic point of departure. Organisms can be considered as fluctuating eddies in a flowing river; they are locally interesting but don’t define the up and down of the flow. Furthermore, it’s clear they are not really bounded by any sort of durable wall.

Tellingly, the two inventors of Gaia, Lovelock and Margulis, each for their own idiosyncratic reasons, were perfectly prepared to skip the focus on organisms as well as the belief that organisms could be defined as atomic entities inside walls. Lovelock, although familiar with physiology, was specialized in the tracing, through highly sensitive instruments, of geochemical pathways and had no interest in organisms per se, the boundaries of which he kept traversing many times freely. As for Margulis, specialized in the long-term history of bacteria, she had made a career of breaking the walls of organisms and replacing them with clouds of overlapping multispecies she called holobionts. Neither of them had any difficulty in considering that the interesting case they should focus on was the widespread default position, when there is no apparent or only a loose coupling, leaving the special case of tight coupling for what it is – an exception that shouldn’t be used as the baseline for all the others. Whatever Lovelock and Margulis were prepared to discover, they knew it should not be taken as some sort of organism, and certainly not as some organism inside an environment that would remain ‘outside’. The very definition of inside and outside should be left open.

Thus, they were perfectly willing to follow a cascade of metabolic pathways as far and as long as necessary. Although there was nothing radical in the idea of taking metabolic pathways as the main tracers, there was a real innovation in the extent to which they were both ready to follow them.

At one extreme, there was the interesting case of how bacteria could have generated enough byproducts to modify the general conditions for any bacteria to grow – or for many bacteria to disappear, as in the case of the invention of cyanobacteria and the release of toxic oxygen in the atmosphere. Here, the loose coupling became visible with the upstream and downstream components connected, although not directly nor quickly: the consequence of metabolic activity of bacteria simply generating limiting or enabling conditions for other bacteria living later in time or elsewhere in space. This contribution from upstream organisms can be given the name habitability, in the sense that they generate a context inside which others have to situate themselves to survive. Nothing more and nothing especially ‘homely’ in what is ‘habitable’: because of what they reject downstream, metabolic activity generates constraining conditions for other entities down the chain to inhabit some place. This is what Margulis meant when she said: ‘Bacteria run the show’. This doesn’t mean there is anything like a plan, or a goal of any sort, and nothing like a search for any kind of optimization, but rather that ‘stuff happens’, that metabolisms have consequences downstream. That’s all. Which is another way of saying that any metabolism enters the game after other entities have started to play and has to catch up. Or that they are entangled with one another. Or that any entity always resides in some ‘inside’ made by an other. Or that the notion of an isolated organism is a contradiction.

Another well studied case is the more tightly coupled situation when it is easier for an observer to notice that entities are busy making sure that what they do enhances the habitability of other entities. These are the cases along the gradient going from niche construction – valleys with beavers’ dams – to what is loosely called ‘superorganisms’ – the paradigmatic case of termite mounds – and indeed to ‘organisms’ – the termites themselves which are in many ways ‘superorganisms’ too. The point here is to imagine a sort of circle or envelope that covers the activity to buckle in one circle the metabolic activity upstream and downstream of any entity. Even here, however, the organism has no isolated or individual existence ⁹ to the extent that we cannot make a distinction between the ‘material context’ and the ‘biological organism’: metabolic pathways cross the divide in all sorts of ways, but the observer is able to trace a virtual line to place inside it a termite, a termite mound, or a whole valley depending on his or her interest and types of data. There is nothing unusual here, the same virtual envelope will be used to link the movement of trapeze artists in one ‘act’ in a show: coupling is an action of joining distinct things together.

At another extremity, we find Lovelock’s intuition that metabolic activity has consequences – if we follow them far and long enough – for what appears at first as the ‘outside’ of any form of life forms, what other disciplines take as the ‘material context’ or the ‘environment’ of ‘life’. It’s important to understand the idea that the atmosphere or indeed the planet – at least the superficial skin of planet Earth – raises exactly the same habitability question as the two situations before. To consider planet Earth ‘in its entirety’ does not mean you shift scale and take it as a different entity than before: it simply means that you have followed upstream and downstream metabolism for billions of years and very far indeed from what traditional disciplines consider as the limit of their interest – physiology, biology, ecology, population dynamics, geography, they would stop at the provisional limit of what they see as their object. But if you follow metabolic pathways obstinately enough, you cross those provisional boundaries: gas accumulates and ends up creating an atmosphere inside which all the other metabolic activities take place. Gaia is not an equivalent of the Earth system, rather Gaia extends as far as metabolism extends.

This does not mean that you, as an observer, have shifted to a bigger level or changed your object of study: it is rather that the object of study itself has generated a change of scale by expanding in time and space and that you have followed metabolism far enough. Actually, what would be really odd would be to stop following the consequences upstream and downstream of any metabolic activity under the pretext that it does not pertain to your disciplinary definition . . . as if a physiologist of termites was balking at studying termite mounds, or if a specialist of bacteria was uninterested in what happens to the oxygen or methane released by cyanobacteria. Following the consequences of one’s action, no matter how strange or painful, is a scientific and even a moral responsibility.

This is an important point because the official story of Gaia is that Lovelock expanded ‘unduly’ a problem of habitability to ‘the whole planet’ that should have been restricted to the limit of skin, superorganism, niche and ecosystems. But exactly the opposite is true: Lovelock refused to artificially interrupt scientific inquiry at some arbitrary point in the chain of consequences created by metabolic activity. By doing so, it turned out that the habitability conditions created by metabolism fed back on the livability of all the other Earth inhabitants. Nothing extraordinary here. The problem is the same at every scale. It is just unusual because of the extent of the inquiry. Retrospectively, it is something of a puzzle to explain how such a simple and non-controversial problem – the study of Earth makes no sense without raising the question of its habitability – has been obfuscated to the point that, even with the Anthropocene now well in sight, it remains controversial to say that the extension of metabolism has generated conditions for other entities and that it is those habitability conditions we call Gaia – as distinct from the organisms-inside-an-environment view.

One of the reasons is that if you choose as your point of departure the bounded organism inside an environment, you have to use two sets of principles, one for ‘life’, another one for ‘material conditions’; one has orientation, or goal function – it maintains its condition of existence – the other has none – it’s a mere concatenation of causes and effects. Or, in another idiom, one reverses the entropic cascade that the other simply follows. The result is that you are going to use tight coupling – that is, the organism – as a model to judge any other questions of habitability, even though that sort of coupling is a rarity when taken at the Earth history scale. If someone claims that the atmosphere produced by bacteria and plants creates habitability for other entities later in the game – itself a completely banal claim – it will become an extravagant proposition if you imply that there is coupling just as tight as what controls blood pressure in an animal. But it is not the original claim that is odd, it’s the presupposition that the rare tight coupling is the only relevant case – when it is the rarest. The mistake in asking the question: ‘Does Gaia have a goal function for habitability?’ is in imagining that the same entity lies at the beginning and at the end, closing the circle much too quickly. A spurious ‘self’ has been elicited where there is none, and this is what triggers a series of even more absurd questions.

This point is crucial, because when some scientists object to Gaia that it cannot elicit a goal function for the maintenance of the habitability of the Earth planet, they are the ones who have created an impossible problem: to have a goal function for some outcome by the very same one who will benefit from it is not the general case. To be a ‘self’ is not a good starting point. But to study what sort of loose coupling has been generated for later participants, since metabolism necessarily has consequences, is an obvious question to raise.

A specific case that required Gaia to solve a ridiculous set of questions was presented by some biologists who fused the two arch-modernist models of atomic individual organisms endowed with the property of calculating their self-interest and demanded of Lovelock whether Gaia is one of them. The sociobiological version of biology – short-lived but very influential, by bad luck, just at the time of Gaia discovery – transformed the discussion of habitability into a parody of scientific discussion. Especially troubling was to present the question of goal and habitability (the ‘for’ in the expression ‘Gaia regulates itself “for” the benefit of life’) into an alternative between competition and cooperation. This way of arguing put the whole Earth history upside down, as if you tried to let the pyramid of Cheops stand on its apex. The question became to decide if the model of isolated entities calculating their benefits through some accounting (a late modern capitalist invention) could explain or not all the cases – what we called the default position above – where there is no coupling, or only a loose one, between what is poured downstream by metabolic process and what comes ‘back’ upstream. And to decide that the first one would be called ‘selfish’ and the other ‘altruistic’, even though it was obvious that in most cases neither of the two adjectives can be applied. Things have consequences. Good or bad? That depends on what happens later in the chain. To ask whether Gaia is based on ‘competition’ or ‘cooperation’ is to miss entirely the mess created by the interconnections of consequences of so many intertwined metabolisms. Margulis warned her readers: ‘Gaia is a tough bitch’.

If the conversation went nowhere with biologists it is because they invented a completely artificial problem by opposing ‘altruistic’ versus ‘selfish’ entities, forgetting that in both cases it requires the same united ‘self’ at the reception and at the sending of the chain: ‘I am selfish and I do this for my benefit only’ or ‘No, I am altruistic and do this for the benefit of others’ implies the existence of an ‘I’. Needless to say, that those – mainly biologists – who have created the spurious problem (‘Show us that Gaia has a goal function for the maintenance of life on Earth’) have made it even more ridiculous when they add the proviso: ‘Show us that Gaia maximizes or optimizes the survival of life on the planet’. The answer is simply that a Gaia so absurdly defined cannot deliver any of those goals – nor for that matter any organism, niche or ecosystem. An absurd question has got an absurd answer. The problem is not with the notion of goal but with that of the ‘self’ having a goal.

The famous Daisyworld model offered a perfect site to disconnect the different couples and to show that there is nothing obvious in placing an entity endowed with the ability of being the same ‘self’ at the entry and the exit points of any metabolism. Instead of one unproblematic agent bounded by a wall, there are hundreds of other situations without any clear-cut coupling of what leaves a metabolism and what feeds it back. And it was just those other cases that the Daisyworld models made visible. Unfortunately, the modeling was construed as an answer to the accusation of teleology and to the selfish/altruistic quandary raised artificially by evolutionary biologists against Gaia (with Gaia taken by its opponents to be an indefinitely inflated organism-in-an-environment). The focus on tightly coupled organisms instead of loose coupling metabolism meant that the discussion went nowhere and that the Daisyworld model lost its chance to show how rare and special is the case that the opponents of Gaia called the natural selection of fully ‘selved’ organisms.

Unfortunately, through a series of mishaps, the conversation, after Gaia discovery, sounded more like a boxing match between two arguments: ‘Yes, Gaia is an organism and indeed elicits a goal function for the purpose of life benefits’ against ‘No, this is impossible; only organisms have goal functions, and Gaia, taken as a whole, has none’. The reason for that missed opportunity is that cybernetic metaphors offered Lovelock a powerful shorthand to give a shape to his intuition at the moment when nobody was prepared to get it. But it was just a shorthand. In a human-made machine relying on cybernetic feedbacks, the close coupling is carefully mounted and a set point is usually determined in advance, after which the system is left to work ‘autonomously’. The cycle, the coupling, becomes what is appropriately called a circuit and there is no difficulty for the engineer to see what function feeds back on which over. The upstream and downstream are so easily recognizable that the notion of function for some goal becomes entirely unproblematic. However, there is nothing ‘autonomous’ in its overall function and it’s enough to step back one level to realize how many ‘heterogeneous’ elements are necessary to make the machine work ‘by itself’. To have one flying bomb reaching its target ‘alone’, you need the whole Army behind it. As soon as you step back, ‘function’ loses its meaning, quite literally, because the up and down stream are coming apart and the situation resembles more that of trapeze artists having difficulty coordinating their move at the beginning of their training, or, as happens so often in war, when everything turns out to be a fiasco. ‘Stuff happens’, but not what was anticipated – the ‘self’ vanishes.

Still, for Lovelock, to talk of the Earth as one cybernetic self-regulated loop allowed him to skip entirely all the discussion about organisms, animals, life and, in general, what biologists had populated the world with. It allowed him to give to the habitability question a powerful summary: Earth behaves ‘as if’ it was a thermostat; let’s follow the upstream and downstream chains of its habitability maintained roughly constant over eons. But such a shorthand, if taken seriously as a real machine, would render the Gaia hypothesis completely crazy for want of an engineer whose intention ‘for’ something could be devised. The only solution was to add a ghostly Creator and to criticize Lovelock (or worse to congratulate him!) for offering a religious definition of Gaia. And it’s true that having given the entity the name of a goddess did not help readers navigate the cybernetic metaphor carefully enough. However, because Gaia is a sui generis entity there is no reason to believe that its individuality can be captured by any sort of metaphor borrowed from a human-made machine. And yet since it is one single totally idiosyncratic adventure in space and time, it does require a proper name to make sure that it’s not confused with any common mechanism.

One of the other reasons why people misunderstand Lovelock’s Gaia so massively has to do with the entrenched illusion that humans are actually able to have a conscious goal function where the beginning and the end of the same self creates a tight coupling, called ‘consciousness’, ‘planning’, ‘foresight’, ‘intelligence’, ‘rationality’ or whatever terms anthropocentric prejudices have devised. And, of course, if you believe that humans are able to plan something for their benefit, and then use this shibboleth to evaluate any other claim for ‘self-regulation’, you will be tempted to dismiss as ridiculous Lovelock’s claims that Gaia regulates itself. ‘Gaia has no foresight’ you would say. Well, it turns out that humans have none either!

Although this argument could have sounded critical in the heyday of modernism, at the time of the Anthropocene it is now much more common sense to recognize that humans behave collectively with the same total absence of consciousness and foresight as, for instance, cyanobacteria at the time of the Great Oxidation event. They do their thing and create consequences that modify deeply downstream the habitability conditions of other life forms and themselves, but there is not the slightest trace of any feedback where the beginning and the end of the circuit would be coupled enough to generate a ‘self’ able to ‘self-regulate’. This new realization of the limits of ‘foresight’ as a general model of purposeful action allows us to shed an entirely different light on the notion of ‘goal function’. Neither humans nor bacteria nor Gaia have selves able to generate negative feedbacks in some nested and coherent (that is, engineered or providential) fashion.

But then where does the notion of goal come from? There are indeed cases where the ins and outs of action are so tightly joined that they form a couple, a circular feedback allowing a ‘self’ to adjust quickly to a situation – animal temperature, making a cup of coffee at home in a familiar environment, catching an acrobat’s hands just in time, and so on. But those situations are rare. The default position is rather the one we started with earlier: actions have consequences far away without any feedback loops. But sometimes they come back to favor habitability conditions of some other entities far in space and time. In which case they might become entrenched or nested into some other earlier loops (sequential selection etc.). ¹⁰ It’s clear that the word ‘goal’ is misleading because the target was not there in advance before the action – contrary to the illusory model of foresight in human action. We should not be talking of a goal toward a target, as an archer aiming at a circle, but rather an extraction of a target after the fact as in the saying ‘it turned out that, in effect, I wanted this which I had not foreseen’.

Actually, all the cases used to show a tight coupling are those where the connection has been finally made after a long training and once it has been entrenched by habit (if in doubt, ask practitioners how long it takes for an acrobat to seize her partner’s hands!). In all cases, there is a goal, that is, a tendency to prolong the metabolic pathway, but its target is a late realization. We are embarrassed here by a misnaming that is as old as Aristotle’s expression of ‘final cause’. The final cause is not final because it defines a target in advance that will somewhat mysteriously draw the action toward the goal – ‘actualizing potentiality’ as in classical philosophy – it is final because it comes after the end, when it has been noticed that through an amazing series of chance happenstances, what was left downstream creates favourable conditions upstream. Finalized would be a better term. And there is no doubt that Gaia has managed to finalize some sort of regulation even though it has no self and no target – which is the normal, widespread, default state of affairs. We are good witness of that since we benefit from the habitability condition created by its long history of influencing what happens downstream of a metabolism.

To move on with the question of Gaia, we should be able to clearly distinguish between ‘having a goal’, ‘being a self’, ‘extracting a target’, ‘entrenching a target into some sort of habit’, ‘joining the dots in one single coupling’ – all of those expressions having been collated and confused in the apparently simple notion of feedback loop.

There is a philosophical reason that makes it difficult to disentangle all those different layers. The notion of goal seems odd, paradoxical, confusing, simply if the baseline of the world is built out of cause-and-effect concatenations, what could be called ‘backward causation’. However, this is not a world of common sense but the result of the imposition, starting in the 17th century, of a highly peculiar inversion of the common-sense experience, let’s say the idea that the world is made of Galilean objects standing side by side and moving only through cause and effect. Compared to a world made like this, any goal function elicited by every single life form seems an anomaly which has to be explained by some sort of epicycles. It’s fair to say that since the 17th century, life forms have appeared as anomalies that require special explanations – vitalism and reductionism being two of the many manners to let epicycles proliferate. There is, actually, a much simpler solution to dispense with epicycles altogether, and that is to start with life forms having a goal (which does not mean a target or a self, as we saw above) and to realize that for life forms concatenations of cause-and-effects are actually the rare case.

It requires only a smattering of history of science to realize that every single case of cause and effect is actually the staging inside some scientific established discipline of a process of discovery that began the other way by going from consequences to the putative cause, and then reversed the order for the purpose of demonstration. The stabilization of a cause and effect relation is always the result of the entrenchment of a habit of thought and inside an institution. Interestingly, the process by which scientists extract causality (linear or circular) through experiments, then stabilization, then staging, follows a path very similar to the extraction of a target out of happenstance that we study through sequential selection. ¹⁰ And there is nothing surprising in this, since for life forms there is no way not to see targets to be extracted in the universe. Entities that have to ascend the entropic cascade – producing information – have no other way to stabilize their precarious state.

This sounds odd only to those who forget that cause and effect is an idealized version of a machine running autonomously and from the running of which the engineer is able to absent him or herself. But this is not the way mechanisms come into existence. If there is one beautiful example of the extraction of a target out of an incredible maze of alternative and totally blind explorations, it is the process of technical innovation. It is only once the innovation has stabilized and after the mechanism has been endlessly improved, repeated, honed that you might begin to believe (but only if you are part of a naïve public) that the machine runs by itself. So mechanism, far from offering the ideal of an automatism, shows, once again, just like scientific discovery except even more vividly, that the life process at work is that of extracting a target out of multiple goal oriented behaviors. And then stabilizing and entrenching it into some institutions – for a while at least.

If mechanism – and the mechanistic philosophy that has been imagined out of this idealized case – has seemed so powerful, it is in no way because it fits the lessons of experience, but for another reason, entirely unrelated. During the Middle Ages, to solve the problem of God’s action in the world, the mechanical metaphor seemed an excellent shorthand (much like cybernetic feedback for Lovelock in his time). But later in the centuries, after the scientific revolution, when the role of God began to be embarrassingly out of date, the metaphor was kept by insisting on the autonomous machine ‘running by itself’ – meaning now ‘without God’. This double illusion – mechanically wrong and theologically fraught – was then taken by scientists as the default position by comparison with which every other activity – including of course life forms – had to be judged. This is how the puzzle of the goal function of life forms began to emerge, totally out of joint with common experience.

Today there is no reason whatsoever to still use this implausible idea of technical innovation and even more bizarre theological idea of a Creator without a God – the ‘blind watchmaker’ of Dawkins’s fame. We might now shift to the commonsense alternative world view: we see, we experiment, we feel only like life forms do – that is, following a goal which is the necessity of moving up the entropic cascade. And the cause-and-effect case appears to us, if not bizarre, at least as a special case, that always develops, unfolds, is stabilized inside assemblages made by and ‘for the benefit’ of life forms –scientific institutions, companies, factories, cities, etc. There is a complete inversion of the background foreground through some sort of a Gestalt shift: while in the mechanistic view, the cause-and-effect is the rule and life forms with their goal seeking appear as the exception; in the alternative view, it is the opposite, and it is sometimes possible to recognize, but with the utmost difficulty, segments of forward causation reigning locally. It is fair to say that on Earth at least, no segment is discernible for some time without the intervention of life forms – what critical zone sciences show so beautifully.

The importance of such a Gestalt switch is that we – the humans, the scientists, the philosophers – reside inside the largest and longest entity having goal function in search for a target around some set point, namely Gaia. Thus, it has become much more relevant to get a clearer idea of where we reside and what we can hope for. All the ideas about what is the ‘Anthropos’ of the Anthropocene, what is Gaia 2.0, what does it mean to ‘control’ or to ‘master’ the new climatic regime, depend on the definition of the world we live in. The ideal domain of the mechanistic worldview has been that of the infinite cosmos or the geophysics of deep Earth. Even though it has seemed plausible, for a few centuries, to take the Earth just as another segment of the cosmos – viewed from the outside – it is no longer reasonable. The inside has to be seen from the inside. In this view, if there is one question that seems odd, it is certainly not ‘how could you believe that Gaia is oriented toward the maintenance of habitability?’; it is, rather, ‘how could you have thought that you could escape the problem of finding the target toward which life forms have conspired for 3.5 billion years?’.