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Special Issue: Solid Fluids: New Approaches to Materials and Meaning
Introducing Solid Fluids
Tim Ingold
University of Aberdeen
Cristia
´n Simonetti
Pontificia Universidad Cato
´lica de Chile
Abstract
This issue opens an inquiry into the tension between solidity and fluidity. This tension
is ingrained in the Western intellectual tradition and informs theoretical debates
across the sciences and humanities. In physics, solid is one phase of matter, alongside
liquid, gas and plasma. This, however, assumes all matter to be particulate. Reversing
the relation between statics and dynamics, we argue to the contrary, that matter
exists as continuous flux. It is both solid and fluid. What difference would it make
were we to start from our inescapable participation in a world of solid fluids? Is solid
fluidity a condition of being in the midst of things, or of intermediacy on a solid-fluid
continuum? Does the world appear fluid in the process of its formation, but solid
when you look back on things already formed? Here we open new paths for theoriz-
ing matter and meaning at a time of ecological crisis.
Keywords
Anthropocene, continuous matter, duration, flux, hydraulics, rheology, solidity
Il peut e
ˆtre utile de se rappeler que le doux dure plus longtemps que le
dur. [It is worth remembering that the soft lasts longer than the
hard.] (Michel Serres, 2009)
1
From Fluid to Solid and Back ... to Liquid?
Solidity can mean many things. A solid ground is one that bears your
weight. It is hard or firm; you will not sink, as in marshland, or fall, as
into the waters of a lake. A solid object, like a cricket ball, is of one
continuous, undivided mass; it is not hollow like a tennis ball. Solid
metal, such as gold, is pure, not contaminated by mixture with other
Theory, Culture & Society
0(0) 1–27
!The Author(s) 2021
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DOI: 10.1177/02632764211030990
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Corresponding author: Tim Ingold. Email: tim.ingold@abdn.ac.uk
TCS Online Forum: https://www.theoryculturesociety.org/
minerals. A talk can last solidly for hours, while bored listeners remain
solidly asleep. A geometrical solid is a figure in three dimensions rather
than two. More than area, it has volume. These multiple aspects of solid-
ity – hardness, undividedness, duration, purity and volume – while they
might not share any unitary essence, nevertheless form a kind of semantic
cluster which points to a certain convergence in experience. It is the
experience of a life that, far from running every which way, has settled
into the grooves of custom. Indeed the Latin dictionary renders the ori-
ginal meaning of the verb solere, from which ‘solid’ is derived, as ‘to be
accustomed’.
In antiquity, as still today, custom revolved in the first place around
trade and markets. The merchant would seek a hard bargain, look for
firmness or reliability in his trading partners or customers, and an assur-
ance that goods are genuine rather than void or counterfeit. If using
currency, he would want to be sure that the coin was of pure metallic
substance, traditionally gold, and that its value was guaranteed by the
authority of the realm. He would look for deals that last. And of course
one of the most important skills of any trader was to be able to estimate
by eye the volume of goods sold by the barrel or basket.
2
Thus every
aspect of solidity would be in play. It is perhaps unsurprising, then, that
the common coin of the late Roman Empire, of relatively low value, was
called a solidus. Army personnel, whose salaries were paid in solidi, were
called soldiers. Many centuries later, in France, you might still measure
your petty cash in sous, while on the other side of the Channel, it would
have been in shillings. In Italy, the balance on your account is saldo.We
easily forget today that all these words go back to ‘solid’, and that they
speak to the custom of commerce.
But what of its purported opposite, fluid? As with solid, the word is of
Latin origin, from fluere, ‘to flow’. Surely, what does not flow – what is
stuck, or fixed firmly in place – is, ipso facto, solid. Yet curiously, all that
is not solid doesn’t flow. When we look at the many meanings of solid,
and consider their opposites, not one of them carries any connotation of
fluidity at all. An object that is not solid is hollow, but hollowness coops
up what lies inside rather than allowing it to run. An impure substance is
contaminated, but many metals are rather soft in their pure state, and a
degree of impurity is necessary to harden them up. That’s why even the
Roman solidi were only around 95 per cent gold. In geometry, while a
polygon on a plane surface has area but no volume, its constituent lines
connect fixed points; there is no movement in them. The two remaining
aspects of solidity, hardness and duration, are particularly perplexing. A
hard winter frost solidifies the ground and turns water into solid ice.
When the weather warms in spring, the ground becomes soft, and the
ice melts back to liquid water. Yet neither softness nor liquidity implies
flow. Marshy ground is treacherous precisely because its water content
remains stagnant. Liquid is fluid only when it runs, and it will not run if
2Theory, Culture & Society 0(0)
contained. And in the case of duration, solidity and fluidity are not
opposed at all, but mutually implicated. The opposite is interruption,
which breaks the flow, whether of talk or sleep.
It seems, then, that while we might start with the fluid and derive the
solid as its converse, turning the conversion around – far from taking us
back to where we started – would lead us somewhere else altogether: not
to fluidity but to hollowness, contamination, planarity, liquidity and
interruption. In short, while solid entities can be formed or configured
against the ground of the fluid, the reverse does not appear to hold. Stone
pebbles rest on a riverbed, icebergs float in the ocean, mountains stand
firm amidst the swirling mists and pouring rain. But how could a river be
locked in a petrified landscape, or the ocean be contained in an icefield,
or the weather in the theatre of a mountain range? A world already
secured in solidity cannot accommodate the flow from which it once
was formed yet which now portends its dissolution. Its regions of non-
solidity are instead configured as gaps, spaces and hollows, as in a Swiss
cheese. They can be filled, but the filling doesn’t flow.
3
To see this, you
only have to place a jar in a running river: you can catch a sample of
water, but you cannot catch the current. Nor can you catch the wind in a
bottle. In one case liquid, in the other gas, is held within the hollow
regions of a solid.
Yet the world we inhabit, and that we know from our experience, does
not resemble a Swiss cheese. It is not full of holes (Ingold, 2011: 24). Nor,
conversely, are its solid regions immune to the flows that envelop them.
Stones are ground into their forms by the forces of the river current; ice is
sculpted by the ocean; mountains by weather. The earth, indeed, seems
solid and fluid at the same time. How can that be? Perhaps, if we cannot
regain fluidity by opposing it to the solid, it might nevertheless be found
as the constitutive dynamic of the solid itself. Could solids retain some-
thing, in their very constitution, of the flux of which they were formed?
Can the solid itself be intrinsically fluid, even as the fluid solidifies? Recall
that it is precisely in the concept of duration that solidity and fluidity
merge. Duration is about how things last, about how they carry on as
they are both formed within and hold out against the flow. It is a word
that links the two senses of hardening and continuity in time. And it is
only by introducing the work of time, we suggest, that the conundrum of
solid fluidity, or fluid solidity, can finally be resolved.
As this introduction and the articles to follow will show, the conun-
drum is not merely of concern to physical scientists tasked with unravel-
ling the secrets of matter. For it is already implicated in an understanding
of the physical world, foundational to modern science, as a domain of
reality whose intrinsic hardness, receding at once into the infinite and the
infinitesimal, resists the efforts of softer minds, bound by the rhythms of
time and life, to fathom it. The distillation of reality that has allowed the
solid to settle as a material substrate from the fluid matrix of its
Ingold and Simonetti 3
generation is part of the same bifurcation that has divided mind from
nature, meaning from matter, and indeed the disciplines of the huma-
nities from the physical sciences. The conundrum of solid fluidity cannot
be resolved on one side of the division or the other. Nor is it a question of
analogy, of treating the material world as a reservoir of metaphorical
resources for concept formation and the construction of meaning. It is
the division itself that requires critical attention. Amplified by techno-
political forces, it has had fateful consequences for the sustainability of
life on earth. By bringing together the solid and the fluid in the fullness of
time, our aim is to undo the division, and to bring matter and meaning
together again. This, we contend, must be an essential first step in finding
a way through an environmental crisis that affects us all.
The Phases of Matter
In the physical sciences, ‘solid’ has acquired a very specific meaning as
one of the possible phases of matter. Others include liquid, gas, plasma
and a strange condition known as the ‘Bose-Einstein Condensate’. Of
these, the first two are familiar from everyday experience; the remaining
two are not, though plasma may, in fact, be the prevailing phase of
matter in the universe at large. Common to all, however, is the premise
that matter is comprised of elementary particles of one sort or another.
The particles may be of different scales of magnitude, from ions, atoms
or molecules to grains. Different phases, then, depend on how these
particles are compounded. With solids, they are so tightly bound that
their freedom to move is severely constrained. From this it follows, first,
that solid volumes are resistant to the pressure of deformation. We
experience this as hardness. Secondly, because of this, the shapes they
assume do not adjust to the shapes of any containers in which they may
be placed. With liquids, by contrast, while the constituent particles are
still close, they are not so tightly bound and have more freedom to move.
So although, like solids, liquids occupy a determinate volume, they
nevertheless hold to no shape and adjust to the shape of any container.
But with gases even the volumetric constraint is lifted. Not only can they
fill a container of any shape; they can also be compressed into a smaller
volume or expand into a larger one.
So-called ‘phase transitions’, from solid to liquid, or from liquid to
gas, are achieved by adding energy, typically in the form of heat. The
more energetic the particles of matter, the more restless they become, and
the looser their configuration. Heat a solid and it eventually melts, at the
point when the ties between its kinetically energised particles eventually
break. Heat a liquid, and it begins to vaporise, as the particles lose any
connection and spread out into the space available. Heat it still further,
and the particles themselves break up, stripping away electrons so as to
leave them positively charged, or depositing them, so as to charge them
4Theory, Culture & Society 0(0)
negatively. With this, the gas is turned to plasma. Though naturally rare
on earth, gases such as neon, argon and helium can be ionised into the
plasma state by charging them with electricity, as in some modern light-
ing applications. The Bose-Einstein Condensate (BEC) goes to the other
extreme, where matter is cooled close to the point of absolute zero, such
that its particles have virtually no kinetic energy at all. At this point, the
particles are no longer distinguishable from one another; rather, they
appear to collapse into one super-particle which, paradoxically, has the
properties of a superfluid. Though long predicted in theory, not until
1995 was the laser technology perfected that would make it possible to
create the BEC in practice.
The BEC is but one of a number of peculiar phases of matter recently
identified at the low energy extreme. While unobtainable under normal
terrestrial conditions, it nevertheless suggests that fluidity could be a
constitutive property of matter even in its most solid state – that what
we take to be particles, divided from one another yet undivided on the
inside, are really the vortices of a flow, with each vortex a locus of spin
rather than an externally bounded entity. Could the different phases of
matter, then, be variations on the theme of solid fluidity? Could all
matter be fundamentally viscid (Simonetti, this issue)? Other, less
extreme examples are not hard to find. Indeed, whether we take a mater-
ial to be fluid or solid may simply be a matter of granular scale. A particle
of sand may be solid with regard to its crystalline structure, but sand en
masse, as in a desert, in dunes, or even pouring though the waist of an
hourglass, behaves very much as a fluid as it is sculpted into forms of
movement such as whirls, waves and swellings. Mudslides, avalanches
and surging glaciers are among many natural examples in which appar-
ently solid matter gives way to flow, often with devastating consequences.
In other cases, it is a question of time. In a famous experiment com-
menced at the University of Queensland in 1927, a quantity of heated
pitch was poured into a funnel with a sealed neck and allowed to settle
for three years. The seal was then cut, allowing the pitch to pour. It took
eight years for the first drop to fall, and since then they have continued to
fall at the rate of roughly one per decade (Edgeworth et al., 1984). The
ninth drop fell in 2014.
Glass is another example of a material that defies any opposition
between solid and fluid (Engelmann, this issue). Heated to over a thou-
sand degrees Celsius in the furnace, it can be moulded or blown to any
shape. When it cools, however, its molecular constituents remain trapped
in their disordered, liquid configuration, causing such internal stress that
it is liable to shatter or explode unless it is properly annealed. In the
annealing process, the glass is kept for a period at a steady temperature
of around 500C, where it hovers between solid and liquid phases: suf-
ficiently hard to retain its shape but soft enough for its internal tensions
to be gradually relieved. Whether, given enough time, glass continues to
Ingold and Simonetti 5
flow even when finally cooled remains a matter of debate. Measurements
of glass in the windows of ancient buildings, such as cathedrals, seemed
to show that it is thicker towards the bottom and narrower towards the
top, leading to the belief that the material had, over the centuries, slowly
and inexorably sunk under its own weight. Though this belief has been
comprehensively discredited (Zanotto, 1998), the liquid solidity of glass
remains an enigma, and is hotly contested by materials scientists.
4
Like
glass, metal also flows, and the fluid-solid threshold is the special domain
of the metallurgist, who occupies the cusp between the two, alternately
heating and quenching his material as he works on it. Even volcanic lava
never fully loses its fluidity on cooling, and in the long course of time the
hardest of igneous rocks, such as granite, exhibit plastic properties.
Perhaps the most ubiquitous instances to combine properties of fluid-
ity and solidity are to be found in the formation of colloids (Szerszynski,
this issue). A colloid is a mixture in which particles of one substance are
suspended in the medium of another, without actually dissolving into it.
Colloids of different kinds can then be classified according to whether the
suspension on the one hand, and the medium on the other, is solid, liquid
or gas. Though ‘gas-in-gas’ appears inconceivable, since the level of dis-
persal is such that no separation between suspension and medium could
be sustained, it is not difficult to find homespun examples of every other
possible combination. In smoke, for example, solid particles are sus-
pended in gas; in volcanic pumice, gas is suspended in solid. In fog,
liquid particles are suspended in gas; in foam, gas is suspended in
liquid. In ink, and in blood, solid particles are suspended in liquid; in
gels, liquid particles are suspended in solids. Liquid-in-liquid gives us
emulsion, while solid-in-solid gives us what is known as ‘ruby glass’, in
which gold salts are added to molten glass, giving it a distinctive colour
when cooled. The case of solid-in-solid, however, is of wider geomorpho-
logical significance, since it bears directly on our understanding of pro-
cesses both of fossilization and of the formation of sedimentary rock.
Reversing the Relation between Statics and Dynamics
Already in the 17th century, the Danish natural philosopher Nicolas
Steno addressed the perplexing question of how solid objects can be
suspended in a solid medium. His dissertation, De solido intra solidum
naturaliter contento (‘On a solid body naturally contained within a
solid’), published in 1669, laid much of the foundation for the science
of stratigraphy (Lucas, this issue). Key to it was the idea that what
appear to us now, as successive layers of rock, were formed over the
ages through the slow sedimentation of particles held in liquid suspen-
sion. Petrified inside the accumulating sediment would be the skeletal
remains of ancient life forms (Simonetti and Ingold, 2018). Yet as sub-
sequent generations of geologists were to show, starting in the 18th
6Theory, Culture & Society 0(0)
century with the Scottish naturalist James Hutton (1795), these solid
layers have been tilted and folded by forces operating over immense
spans of time, which operate today as they have always done in the
past. The earth, for Hutton, is not – and never was – fully formed, but
ever in formation. In this formative process, not only does solid rock
emerge from liquid suspension, but the rock itself is also semi-fluid in its
susceptibility to contortion. As with a slab of marble, the very texture of
rock can preserve these contortions in its wave-like folds.
5
The turn, here, from solid to fluid reverses the relation between statics
and dynamics, putting movement, as it were, up ahead rather than in the
wake of the forms to which it gives rise. To depart from the solid earth is
to see it as having already precipitated out from the processes of its
formation; to appreciate its fluidity is to enter into these formative pro-
cesses, and to go along with them (Simonetti, 2019b). This turn has been
at the root of many celebrated debates in science. In the field of glaci-
ology, for example, it lay at the heart of a bitter feud between two of its
most prominent mid-19th century pioneers: David Forbes, who main-
tained that the glacier moved as a continuous viscous fluid, and John
Tyndall, who insisted, to the contrary, that glacial movement was due to
the fracturing, repositioning and refreezing of solid ice under pressure
(Simonetti and Ingold, 2018; Simonetti, this issue). Around the same
time, a similar argument raged among astronomers who, for the first
time, had developed telescopes powerful enough to observe the forms
of distant nebulae. What did they see? Was the nebula a multitude of
discrete stellar objects held together by loose attraction, or the fluid for-
mation of a continuous gaseous material? William Parsons, third Earl of
Rosse – whose giant reflecting telescope, nicknamed ‘The Leviathan’, was
at the time the biggest in the world – took the first view. With his
Leviathan, he claimed, he had already managed to resolve the celebrated
Orion nebula into its individual stars, and he proceeded to draw it thus,
with a stippled, pointillist effect. His contemporary and rival John
Herschel, however, took the second view, and drew the nebula as a
wispy and vaporous cloud, including no discernible objects at all
(Nasim, 2013).
As these examples indicate, rather more is wrapped up in the idea of
fluidity than the liquid phase of matter. For as we have already sug-
gested, fluidity comes before solidity; liquidity afterwards. It is the dif-
ference, if you will, between formation and break-up. Forbes saw the
glacier, as Herschel saw the nebula, as undergoing continuous formation
within a fluid if viscous medium. But Tyndall and Rosse, starting from
the imagination of a world already condensed into solids, saw them
smashed into myriad fragments, jostling for position in a collectivity
that, by virtue of the looseness of their attachment, was perceived to
behave like a liquid, or even like a gas. From one perspective, the mater-
ials of the glacier or the nebula cohere, flexibly going along together in
Ingold and Simonetti 7
increasingly sticky unison; from the other, their respective fragments
adhere, momentarily attaching to one another only to break away and
reattach in other positions. In ‘coherence’ and ‘adherence’, the prefixes
co- and ad- align with the distinction between viscous formation, on the
one hand, and punctuated break-up and reattachment on the other.
There are countless examples of word pairings where these prefixes, of
Latin derivation, do the same work, including ‘congregation/aggrega-
tion’, ‘conjoin/adjoin’, ‘comply/apply’, ‘contract/attract’, and so on.
Underlying them all is a fundamental contrast between with-ness and
at-ness. ‘With’ means accompanying things in their passage through
time. Everything has its story, its particular temporal pathway. ‘At’,
however, cuts transversally across these pathways: it marks, in the felici-
tous phrase of geographer Doreen Massey, ‘the simultaneity of stories so
far’ (Massey, 2005: 10–12). In short, at-ness offers a snapshot of prox-
imity; with-ness endures (Ingold, 2020: 24).
The turn from at-ness to with-ness marks a perspectival shift: from the
being of materials to their becoming, from succession to duration, from
the identity of elements to the heterogeneity of substance, from thinking
in terms of stability and change to thinking in terms of growth and
movement. There is more to this shift, however, than any simple oppos-
ition between statics and dynamics might suggest. Classical approaches
in rigid-body dynamics, hydrodynamics and aerodynamics still start
from the assumption that matter is made up of discrete particles, such
that its solid, liquid and gaseous phases depend on the strength or loose-
ness of their attraction. The dynamics of motion, then, are derived from
the stable properties of particulate matter, in statistical aggregate. But to
put the relation between statics and dynamics in reverse is to start from
the opposite assumption, namely that all matter is continuous, and that
its structure depends on the manifold ways in which the continuum can
be folded, stretched, twisted, spun or otherwise contorted. With the con-
tinuum assumption, indeed, fluidity is not a special case; rather ‘flux is
reality itself’ (Deleuze and Guattari, 2004: 398). All matter is fluid, inso-
far as its contortions give rise to distinct forms, but it is also viscous,
insofar as these forms last long enough to be recognizable. A world of
becoming, therefore, is not composed of different phases of matter, either
singly or in combination, but is rather emergent from within a field of
forces constituted by the interplay of plasticity, viscosity and elasticity.
Such is the world of continuum mechanics.
Within the continuum, a wide range of conditions can be distin-
guished. On the one extreme is material so solid that, even if temporarily
deformed by the application of stress, it will instantly spring back to its
original shape once the stress is removed. On the other extreme is mater-
ial so liquid that no amount of beating, shaking or stirring will affect its
runniness. Water at room temperature is a good example, albeit not a
perfect one. In between, however, lie a plethora of materials from
8Theory, Culture & Society 0(0)
ostensibly solid yet nevertheless plastic materials that, once deformed,
will return to shape only gradually, if at all, to ostensibly liquid materials,
such as a suspension of starch in water, which thickens or even solidifies
under pressure.
6
These materials, which defy any division between solid
and liquid phases, are the special preserve of the branch of continuum
mechanics known as rheology (from the Greek rhe
´o, meaning ‘flow’). As
much concerned with the fluid formation of solid bodies as with their
deformation, rheology effectively dissolves the conventional distinction
between solid and fluid mechanics, uniting the plasticity of solids with the
viscosity of liquids within a single matrix of variation.
Even phenomena that appear to result from the interaction of discrete
entities, such as the behaviour of cars in traffic, can be modelled rheolo-
gically as a continuum of variable and fluctuating density (Szerszynski,
this issue). Rheology is most at home, however, with the kinds of sub-
stances we might describe as ductile, including muds, sludges, suspen-
sions and polymers. It is also applied to organic materials, including
bodily fluids and soft tissues. Indeed, many of the materials we com-
monly work with in everyday life are of a rheological, solid-fluid
nature: think, for example, of wood, an apparently solid substance
whose undulating grain attests to its former life as part of a living tree;
or of wool, spun from hairs that once grew on the backs of sheep; or of
silk, a material that deforms under tensile load but slowly and eventually
returns to its original shape after the load is released. In fact, one of the
first studies to depart from the classical postulates of Newtonian physics
was by German physicist Wilhelm Weber, published in 1835, on the
visco-elastic properties of silk (in Walters, 2010). Common foodstuffs,
too, are ductile, or else we could neither chew nor digest them. This
includes cereals, milk, butter, honey, eggs, meat and fish. In food prep-
aration, operations such as heating, simmering, shaking and stirring can
make ingredients more or less runny or sticky, smooth or lumpy. Much
of the art of cookery lies in the precise management of these transitions.
The Materials of the Living World
Yet while cooking, a rheological art par excellence, inhabits the solid-
fluid continuum, we nevertheless routinely distinguish between liquid and
solid foods, especially in connection with feeding human infants who, at
the start of life, have neither the dentition nor the digestion to cope with
tough materials. It does not take children long to learn that eating is one
thing and drinking another, and that they call for different operations of
the mouth, such as chewing and sipping. In these and countless other
examples, solidity and liquidity are revealed, in our experience, less as
states of matter than as properties of materials, all of which are variations
of fluidity. And when we shift our point of view from the physical to the
life sciences, it is these properties that come to the fore.
Ingold and Simonetti 9
Matter is constitutive of the physical world; materials make up the
environment for animate beings, whether human or nonhuman, engaged
in certain forms of life and equipped with particular capabilities of action
(Gibson, 1986: 8; Ingold, 1992). The emphasis here is not so much on
what materials are as on what they do – on what they afford for those
who would make use of them, or on how they behave in response to their
interventions. Fresh water, for example, affords drinking for a thirsty
human, but for the fish it affords swimming, and for the water-boatman
that skims the surface it affords support. What matters in the first case is
its ingestible substance, in the second its fluid dynamics, and in the third
its surface tension. Thus, unlike phases of matter, the properties of
materials always point both ways: both to the stuff itself and to the
capacities of the organisms whose lives depend on them. For humans,
these properties are found as the predicates of such action verbs as (in
English) strike, bend, squeeze, break, rub, cut, slice, scrape, grind, dig,
stir, pour, and so on. If you say ‘break’, you know the material is hard
and brittle; if you say ‘bend’, you know it is soft and pliable; if you say
‘stir’, you know it is runny. At the dinner table, the knife is for cutting,
the fork for spearing, the spoon for scooping. But you can no more cut or
spear liquids than you can scoop solids. These properties, and others, are
not given in matter as such, but are immanent in the ways in which
materials are historically conjoined with real lives, depending on the
manner of their engagement with the surroundings, the dynamics of
movement and gesture, and the tools and techniques brought to bear.
Here, solidity and fluidity, understood as material properties of an
environment rather than as states of the physical world, take on different
and decidedly double-edged meanings. They can both assist life and
impede it. Any living creature, as it makes its way in the world, has
perforce to strike a balance between its more solid and more fluid mater-
ials. For terrestrial creatures like ourselves, a solid ground affords sup-
port, yet only so long as it remains beneath our feet. Fluidity, by
contrast, affords movement, yet only so long as it remains above
ground, in the atmosphere. Were fluidity to invade the space of support,
or solidity the space of movement, disaster could ensue, as when solid
ground gives way to marsh or quicksand, engulfing the traveller, or
where we find ourselves stuck, as on the road in the gridlock of a traffic
jam or out at sea in frozen Arctic ice. In practice, we have to make the
most of what the earth offers for support and of what the atmosphere
offers for movement without either sinking in or getting stuck. For so
long as anything lives, there is no keeping the two apart. For things to
grow, rainwater must percolate into the earth even as vegetation breaks
the ground to reach the light. There is indeed no more fertile medium
than a viscous colloidal mud or sludge formed of solid, nutrient-rich
particles in fluid suspension, as found, for example, in alluvial river
deltas (Krause, this issue) or on land subject to irrigation.
10 Theory, Culture & Society 0(0)
Sludge, however, is anathema to the modern project, the overriding
aim of which is to build a sedentary civilisation on solid foundations,
superseding the fluid, wandering life of hunter-gatherers and wild beasts,
or of pastoral nomads and their herds. Most contemporary polities adopt
a riverine perspective that constructs the landscape as a mosaic of solid
grounds, suitable for settlement, dissected by channels for draining sur-
plus water. From this perspective, solid fluidity, or fluid solidity, comes
to be regarded more as a condition of anomalous hybridity than as one
of original undifferentiation. The division between solidity and fluidity is
not, however, given a priori, as a fact of nature. Quite to the contrary, it
takes considerable feats of environmental engineering to wrest solidity
from the earth, and to drive out its more unruly, fluid elements
(Gruppuso, this issue). Land reclamation and urban paving require
liquid residues to be contained, and their runs to be restricted to streams,
canals and pipes, lest they erode or dissolve the fabric of the city. Yet
lively materials, ever on the move, are prone both to have their say in
how solidity is engineered and to subvert the intentions of its agents as
soon as the work is done, or once maintenance turns to neglect
(Meulemans, this issue). Flooding events, occurring today with increas-
ing frequency, serve as forcible reminders of the fragility and imperman-
ence of the foundations on which we build.
Floods are not of course the only extreme environmental events that
shake our confidence in the solidity of the ground. Both heavy rains and
earth tremors can trigger landslides and mudflows, sometimes engulfing
entire communities. The poor, lacking the resources to reclaim or con-
solidate their lands, are invariably at greatest risk, for the distribution of
access to reliably solid ground maps closely onto global inequalities of
wealth and power. Yet none can escape the fact that human civilisation,
in its entirety, rests on the thinnest and most unstable of crusts, covering
the inexorably churning mass of hot, viscous rock making up the upper
layer of the earth’s mantle (Clark, this issue). During earthquakes the
crust itself behaves as a fluid, conducting seismic waves that rock build-
ings like ships at sea. The ancients knew to build in ways that would ride
the storm (Tonna et al., 2018). Earthquake damage has increased in the
degree to which builders have assumed foundations to be solid by
default. This assumption, however, has proved increasingly difficult to
sustain as anthropogenic climate change, leading to sea-level rises, more
frequent flooding and melting permafrost, overwhelms our efforts to
keep the solid and the fluid apart. Are we perhaps, in this epoch of the
Anthropocene, finally rediscovering what was obvious to our predeces-
sors, namely, that in a habitable world, solidity and fluidity are
inseparable?
7
This is a lesson we can still learn from many of the world’s indigenous
peoples, who experience the ground not as a solid basis of support,
separating the earthly substance below from the aerial medium above,
Ingold and Simonetti 11
but as a zone of interpenetration in which earth and atmosphere mix and
mingle in the ongoing generation of life (Ingold, 2011: 115–25). For the
inhabitants of this zone, it is not enough to say of the land, as did Karl
Marx (1930: 173), that ‘it provides the worker with the platform for all
his operations’ (Simonetti, this issue). In the experience of indigenous
peoples, there is more to the land than a solid surface to stand on. It is
rather a milieu suffused with vitalities of all kinds. Along with its nonhu-
man denizens and elemental powers such as rivers and glaciers, it is
sensate and responsive to human endeavours (Cruikshank, 2005). Yet
this responsiveness is imperilled by the relentless expansion of solid infra-
structure and the consequent disruption of those very flows upon which
the continuity of life depends. What difference would it make if, instead
of persisting with ever less sustainable endeavours to extract solidity from
the fluid, we were to follow premodern and indigenous precedent, and to
take, as our point of departure, our inescapable participation in a solid-
fluid world? To make a start in answering these questions, we return to
rheology.
Intermediacy and Scale
The founders of rheology envisaged a world in which everything flows,
even things which to mortal eyes appear solid. Among these founders
was the Israeli scientist and engineer Marcus Reiner. Reiner liked to
invoke the Old Testament story of the prophetess Deborah, who sang
of how even ‘the mountains melted from before the Lord’.
8
According to
Reiner:
Deborah knew two things. First that the mountains flow, as every-
thing flows. But, secondly, that they flowed before the Lord and not
before man, for the simple reason that man in his short lifetime
cannot see them flowing, while the time of observation of God is
infinite. (Reiner, 1964, in Walters, 2010: 92)
Reiner went on to propose what he called the ‘Deborah number’, defined
by the ratio of the ‘time of relaxation’ to the ‘time of observation’. There
is the time it takes for a material to adjust to an applied force through the
dissipation of tension throughout its mass. And there is the time avail-
able for the observer to witness the process. Depending on the ratio,
Reiner explained, a material will appear more or less solid. The mountain
appears solid to human eyes because its time of relaxation is vastly in
excess of the span of human life. But it appears fluid in the eyes of God,
who has all the time in the world to watch. Likewise, permafrost appears
stably solid within the timeframe of human engineering, but chronically
unstable when viewed over longer spans of earth history (Krause, this
issue). Under the concept of the Deborah number, then, the solid and the
12 Theory, Culture & Society 0(0)
fluid appear to merge in a single continuum of variation. Indeed, Reiner
was convinced that with his number he had laid the foundation stone of
rheology (Walters, 2010). Combined in it, however, are two, somewhat
contrary impulses. On the one hand is the scientific aspiration to attain a
God’s-eye view. Evidently, Reiner saw rheology as part of the ambition
of science to transcend the perceptual horizons of mortal life. On the
other hand, however, lies an acknowledgement that a rheological take on
reality can only be relative to the capabilities of the observer. This dupli-
city continues to compromise attempts to come to terms with the mater-
ial world through concepts of space, time and environment.
A case in point is psychologist James Gibson’s ecological approach to
visual perception. Where Reiner was at pains to distinguish the mortal
from the God’s-eye view of the mountain, Gibson distinguished the ‘envir-
onment’ from what he called the ‘physical world’. We have already seen
how this distinction separates a focus on the properties of materials, typ-
ical of the life sciences, from the preoccupations of physical science with
the phases of matter. The reality of the physical world is there, in and for
itself, regardless of the presence or absence of any living inhabitant. This is
the reality that a modern science like physics affects to grasp, on scales
ranging from the sub-atomic to the inter-galactic. Environmental reality,
by contrast, exists only as its material constituents are drawn into the way
of life of the organism whose environment it is. It is, in that sense, funda-
mentally relational, and as such the subject of study in the psychology of
perception. The physical world, in short, is reality of; the environment is
reality for (Ingold, 1992: 44; 2011: 30). That is why, as Gibson (1986: 8)
puts it, ‘the term physical environment is ... apttogetusmixedup’.It
conflates the two realities, respectively objective and relational.
Yet Gibson, too, is not innocent of mixing things up, for he promptly
goes on to distinguish the environment from the physical world on an
altogether different criterion, namely that of metric scale.
The world of physics encompasses everything from atoms through
terrestrial objects to galaxies. These things exist at different levels of
size that go to almost unimaginable extremes. The physical world of
atoms and their ultimate particles is measured at the level of mil-
lionths of a millimetre and less. The astronomical world of stars and
galaxies is measured at the level of light-years and more. Neither of
these extremes is an environment. (Gibson, 1986: 8)
Environments, Gibson explains, are of an ‘intermediate’ scale, on a par
with the size-range of the animals in relation to which they are consti-
tuted. And as such, they nest within phenomena of larger scale, while
nested within them are phenomena of a smaller scale. Even on its own,
intermediate scale, the fine-grained structures of an environment nest
within those of a coarser grain. However, the totality of this nested
Ingold and Simonetti 13
structure, from the gigantic to the infinitesimal, can only come within the
purview of a vision that transcends the world, not one that is situated
within it. You cannot see ‘nesting’ from the inside. It is therefore inev-
itable that as he turns from defining the environment in relation to the
organism to defining it as of intermediate metric scale, situated between
the extremes of micrometres and light years, Gibson ends up relinquish-
ing an organism-centric perspective for the universalising perspective of
physical science.
What Gibson does here for space, the anthropologist Claude Le
´vi-
Strauss does for time. At issue here is the intermediacy of history, in a
nested series of temporal scales. For the historian wishing to escape the
dilemma that every gain in interpretative nuance entails an equivalent
loss of explanatory power, there are – according to Le
´vi-Strauss – but
two ways out:
either from the bottom, if the search for information leads him from
a consideration of groups to one of individuals, then to their motiv-
ations, which belong to their personal history and temperament,
that is, an infrahistorical domain ruled by psychology and physi-
ology; or from the top, if the need for understanding provokes him
to put history back into prehistory and this into the general evolu-
tion of organized beings, which can only be explained in terms of
biology, geology, and finally cosmology. (Le
´vi-Strauss, 2020: 298)
9
But these two ways are really one: a single movement of reduction that
takes us from the domain of situated, historical experience, through vari-
ous levels of biology (developmental and molecular) to chemistry and
physics. At each stage in the reduction, short-term elementary events and
interactions become even shorter, and the long-term they occupy even
longer: the approach towards zero in the former is also an approach
towards infinity in the latter (Ingold, 2016: 141–2). In science, temporal
attenuation and extension, nuclearity and deep time, are two sides of the
same coin (Simonetti, 2019a; Engelmann, this issue).
Now whether, with Gibson, we treat the environment as spatially
intermediate, or, with Le
´vi-Strauss, we regard history as intermediate
on the axis of time, this logic indexes a shift in the meaning of intermedi-
acy, from the relational quality of observers being in among the matters
of their concern to the middle range on a quantitative scale of diminution
or enlargement, running from micro to macro. In terms of the traditional
hierarchy of academic disciplines, this is a shift from ‘soft’ to ‘hard’.
Might we find a corresponding shift in the meaning of solid fluidity, or
fluid solidity, from the intermediacy of life in medias res to a scale of
reckoning on which lie the most durable of solids and the most liquescent
of fluids, and all points in between? And could it lie behind the conver-
sion of Deborah’s prophecy into a number? God, after all, is not a
14 Theory, Culture & Society 0(0)
scientist, nor is the world, in any sense, an object of His creation. When
Deborah sang that mountains melt before the Lord, perhaps she was
professing how, in the presence of God, she felt the infinite immensity
of His creation at the very core of her being. Perhaps she, too, mortal
though she is, could bear witness to the original flux of the earth, as it
were from the inside, enfolded into every moment of existence.
Indeed, sounding very much like a latter-day Deborah, the Victorian
critic and connoisseur John Ruskin demanded of the artist just such a
vision: one that enters into ‘the deep, the calm and the perpetual’. Who
can tell me, Ruskin intoned,
of the forms and precipices of the chain of tall white mountains that
girded the horizon at noon yesterday? Who saw the narrow sun-
beam that came out of the south and smote upon their summits
until they melted and mouldered away in a dust of blue rain? Who
saw the dance of the dead clouds when the sunlight left them last
night, and the west wind blew them before it like withered leaves?
(Modern Painters, Vol. 1, 3.343–8, 1843, reproduced in Ruskin,
2004: 9–10)
The artist, for Ruskin, is one whose senses are so attuned that they find
an eternity enfolded in every moment, deep perpetuity in a never-to-be-
repeated present. To catch that instant when the rain shower melted the
mountain summits is to feel the pulse of time everlasting. Or as the
philosopher Maurice Merleau-Ponty (1964: 168) would put it, it is as
though, in that eternal moment, the eyes of the painter, like those of a
newborn, were opened for the very first time: ‘the painter’s vision is an
ongoing birth’.
Feeling Forward, Looking Back
The mathematician and philosopher Alfred North Whitehead, a man of
deep religious conviction, believed that attending to the continuous birth
of the world, witnessing its creation from within, was tantamount to
entering into the presence of God. But such attention was equally fun-
damental, for him, to the attitude of science. Whitehead was keen to
emphasise the difference in perspective that comes from relinquishing
our view of the world from the outside, as a fait accompli, for a position
from the inside of its coming-into-being. From the outside you see things
of this kind and that, precipitated from the flux of their formation, and
arrayed in an environment. But from the inside each thing turns out to be
none other than the process of its own self-creation, a process that, at
each and every moment, enfolds an entire universe into a singular
nexus.
10
The world, then, appears fluid when you enter intuitively into
its formative process, but solidifies in the instant that you turn your back
Ingold and Simonetti 15
on it, viewing it through the eyes of an intellect which – as Whitehead’s
contemporary, Henri Bergson, would put it – ‘are ever turned to the
rear’. The intellect, according to Bergson, is constitutionally averse to
the ‘fluid continuity of the real’, and promptly solidifies anything with
which it comes into contact (Bergson, 1911: 48–9, 319). Thus does the
rearward view of science break up the irreversible flow of temporal
experience into solid fragments, to be strung out in a time that is now
abstract and reversible, like beads on a necklace.
11
Could the distinction between fluidity and solidity, then, come down
to the direction of travel? Is it the difference between feeling one’s way
forward, improvising a passage through a world undergoing perpetual
birth, and looking back, reconnecting discrete entities, now closed in on
themselves, along a route already travelled?
12
This, precisely, is what
William Blake, poet and visionary, proposed in a stanza of his epic
work Milton, dating from 1804:
The nature of infinity is this: That every thing has its
Own Vortex; and when once a traveller thro’ Eternity
Has passed that Vortex, he perceives it roll backward behind
His path, into a globe itself infolding; like the sun:
Or like a moon, or like a universe of starry majesty,
While he keeps onwards in his wondrous journey on the earth.
(Blake, 1907: 11)
13
Thus the fluid vortex into which you enter appears to turn, as it recedes
in your wake, into a solid body. But Blake had illustrious predecessors.
One was the Roman poet-philosopher Titus Lucretius Carus. In his trea-
tise De Rerum Natura (‘On the Nature of Things’) of circa 50 BCE,
Lucretius argued that there are things in the world only because slight
deviations in the flux of matter, raining ever downwards like water over a
fall, create regions of turbulence wherein it is pulled aside and, albeit only
for a while, revolves on itself before re-entering the flow. We mortals
perceive the resultant forms, but not the movement that gives rise to
them. That is why, as Lucretius explains, despite the veritable commotion
of its material constituents, ‘the universe itself seems to be standing still’
(Lucretius, 2007: 45). In a world where movement is all, and all is in flux,
we see ourselves surrounded by immobile solids.
From Lucretius, a direct line leads to Bergson. If there’s a difference, it
is that for Bergson the great flux of matter, out of which everything is
formed, rises upwards, like a blast of hot air, rather than cascading
downwards as in a waterfall. But for Bergson, too, living things are
formed when the material flux, deflected from its otherwise rectilinear
course, temporarily goes into a spin.
16 Theory, Culture & Society 0(0)
Like eddies of dust raised by the wind as it passes, the living turn
upon themselves, borne up by the great blast of life. They are there-
fore relatively stable, and counterfeit immobility so well that we
treat each of them as a thing rather than as a progress, forgetting
that the very permanence of their form is only the outline of a
movement. (Bergson, 1911: 128)
The line from Lucretius to Bergson, in the eyes of philosopher Michel
Serres, describes nothing less than an alternative history of the physical
sciences – alternative, that is, to the mainstream narrative rooted in the
solid mechanics of Galileo – founded on the premise of the fundamental
fluidity of matter. Every being, for Serres, is a vortex, ‘a dispersal that
comes undone’ (Serres, 2000: 37). It was from Serres that philosopher
Gilles Deleuze and his collaborator, psychoanalyst Felix Guattari, sourced
their idea of a ‘hydraulic science’ that, ‘rather than being a theory of solids
treating fluids as a special case, ... is inseparable from flows’ (Deleuze and
Guattari, 2004: 398). A world of vortices within vortices, as Deleuze puts it
in The Fold – his study of Leibniz and the Baroque – yields an ‘infinitely
porous, spongy or cavernous texture ... caverns contained in caverns’
(Deleuze, 1993: 5; see Szerszynski, this issue).
Hydraulic science, say Deleuze and Guattari, has always existed along-
side, and in an uneasy tension with, the solid science of the state. While the
state, in seeking to exert sovereign control over a territory, contrives to
channel liquid elements within such rigid structures as conduits, pipes and
embankments, it can do so only thanks to the very power of hydraulics it
seeks to subordinate, to wrest islands of solidity from the matrix of the
fluid.
14
Hydraulics, placing dynamics ahead of statics, derives solid from
fluid; the state, placing statics before dynamics, extracts liquid from solid.
Caught between state science and hydraulic science are technicians –
builders and engineers – tasked with the application of designs and
plans, ruled from on high, in a fickle and inconstant world comprised of
fluid materials that are no more predisposed to fall into their designated
structures than they are to remain in them (Gruppuso, this issue). As the
environmental pundit Stewart Brand (1994: 2) puts it, ‘the idea is crystal-
line, the fact fluid’. There is a mismatch, a kink, between the two. Builders
and engineers inhabit this kink (Ingold and Hallam, 2007: 4). For example,
in excavating the foundations for large buildings such as tower blocks,
engineers struggle to protect the excavated void from flooding or its sides
from caving in under pressure of forces of turbulence distributed through-
out the ground mass (Meulemans, this issue). No amount of prior calcu-
lation or theoretical modelling can prepare for all eventualities, and every
builder knows that the work will necessarily involve a measure of prac-
tical improvisation on site. Builders and engineers, it seems, are fated
Ingold and Simonetti 17
to face both ways, to look back and to feel forward at one and the
same time.
Explorations at the Boundary
The articles gathered in this issue were originally prepared as part of a
wider project. Entitled ‘Solid Fluids in the Anthropocene’, the project
responded to calls to rethink the relationship between human and earth
sciences, in an epoch in which humans have become the leading force in
shaping the earth’s history. We do not claim that the convergence of
geological and social phenomena is unique to the present epoch; on the
contrary, we believe there has never been a time when they could truly be
separated. But the onset of the Anthropocene compels us to attend to this
inseparability as never before. With rapid anthropogenic changes to
earth system dynamics, the illusion that the planetary surface affords a
solid platform for the enactment of human affairs, or that these affairs
are carried on in a domain that floats above the fixities of the physical
world, can no longer be sustained. Traditional divisions between ‘hard’
and ‘soft’, or ‘long-term’ and ‘short-term’ phenomena, need to be revised.
To focus our discussions, we resolved to concentrate on things and
materials that, in their histories and properties, have defied any strict
opposition between solidity and fluidity. With this focus, however, it
soon became evident that the solid-fluid conundrum is by no means
tied to the specifics of the Anthropocene. It rather belongs to a much
deeper history of relations between matter and meaning both within and
beyond the Western intellectual tradition. For this reason, we chose not
to confine our reflections to the horizon of the Anthropocene, but to
open them to more extensive historical terrains. This approach is also
adopted by the authors of the articles assembled here. In the following
paragraphs we introduce each in turn.
There can be few environments in which solid and fluid elements are
more comprehensively imbricated than the deltas of major rivers. In the
first article of our collection we find the anthropologist Franz Krause
engaged in fieldwork in the delta of the Mackenzie river, in the northwest
Canadian Arctic, as part of a wider comparative study of delta life from
regions around the world.
15
In every region, these ‘hydrosocial’ environ-
ments are subject to pronounced oscillations between more or less solidly
grounded or amphibious lifeways, which have only intensified and been
rendered more uncertain through the effects of climate change. Particular
to the Arctic region, however, is that these oscillations include seasonal
cycles of freezing and thawing, which can alternately solidify water and
liquefy mud. Here, too, rhythms are becoming out of joint. Yet the idea
of ‘climate change’ misleads, in so far as it presupposes a preceding epoch
of stability. Building on the thinking of theorists and philosophers
18 Theory, Culture & Society 0(0)
indigenous to the region, Krause shows that in the experience of its
inhabitants, the Arctic environment has never been stable or predictable.
It is, rather, vital and dynamic, and the task of life has always been to
respond to this dynamism, not passively but through pragmatic interven-
tions that are as ingenious as they are inventive, yet always respectful.
Key to these interventions, especially relating to travel and construction,
are judgements of time. Solidity and fluidity in the Arctic, as Krause
demonstrates, are fundamentally dependent on the tempo of seasonal
oscillations and their rhythmic interrelations.
With Paolo Gruppuso, in our second contribution, we turn to a very
different site of anthropological fieldwork, the Pontine Marshes (Agro
Pontino), around 40 miles south of Rome. Once a place of woodland and
swamp, occupied for some nine months of every year by a transhumant
population engaged in hunting, animal husbandry, fishing, and the pro-
duction of charcoal, the Marshes also had a fearsome reputation among
city dwellers as a place of bad air (whence the term malaria) and fever,
smelly and squelchy, virtually uninhabited and uninhabitable. During the
1930s, in a massive campaign of environmental engineering directed by
the fascist regime under Benito Mussolini, the entire region was drained.
Presented as a war against nature, and undertaken with heavy machinery
and explosives more suited to the battlefield, the landscape was levelled
for cultivation on an industrial scale and for paving in readiness for
urban development, while a network of channels and ditches took
away the aqueous effluent. With the solidification of the marsh, then,
went the liquefaction of its originally fluid medium. Solid and liquid were
separated out. Yet looking back on this transformed landscape, with eyes
more sympathetic to the subtle ways in which, over the centuries, human
lives had both shaped and been shaped by the rich and heterogeneous
ecology of the Marshes, Gruppuso reveals how the dream behind the
reclamation project, of establishing human mastery over nature once and
for all, has crumbled. Solid grounds soon revert to an earlier fluidity once
their upkeep is neglected, leaving a legacy of rusting machinery, aban-
doned quarries and encroaching swamp.
Our third contributor, Germain Meulemans, takes us from the solidi-
fication of the land to the art of foundation building. The majority of
modern urbanites, as they go about their business in the city, pay scant
regard to the foundations upon which its architecture rests. Save on a
construction site, they are normally invisible, fostering the impression
that the ground already offers a solid stage upon which real buildings
have only to be placed – much as models, in an architectural studio,
stand on a baseboard. For the most part, we are confident that the
ground will not cave in. Yet as Meulemans shows, this confidence is
misplaced, as we find to our cost when buildings suffer subsidence or
sinkholes suddenly open up beneath our feet. For in reality, the solidity
Ingold and Simonetti 19
of the ground is not given. It has to be engineered, and it is here that the
work of foundation builders comes into its own. Beneath the hard surfa-
cing of the city, the earth is only contingently solid, and its unruly behav-
iour defies prediction and control. Compelled to negotiate with materials
that will insist on going their own way, foundation builders require a
knowledge of the ground that is both local and intimate. Below the city
of Paris, where Meulemans carried out his fieldwork, lies the basin of the
River Seine, whose innumerable tributaries and side channels continue to
meander through semi-saturated soils, while the river itself seeks ever to
return to its original bed. The challenges of wresting solidity from this
turbulent, semi-fluid mass are formidable. Overcoming them calls for
relentless effort.
The instability of the soil is a problem not only for foundation
builders, however. It is also faced by archaeologists, as Gavin Lucas
shows us in the fourth contribution to this collection. The problem is
in part a practical one: working the vertical face of an excavated trench,
Lucas recalls his worry that at any moment, the face could cave in,
burying him alive. Fortunately, the soil deposit was of thick clay,
which was actually stiffened and made more compact by the heavy
rain falling at the time. However, the propensity of soils to flow disturbs
any idea that archaeological deposits fall neatly into discrete strata.
Water, seeping through the layers, can redistribute the substances it
encounters through leaching, while tree-roots or earthworms can mix
them up to the point where they are no longer distinguishable at all.
Deposits, then, are mutually permeable, combining properties of solidity
and fluidity in their colloidal composition. As Lucas shows, they might
be better characterised on the axes of durability and permeability, both
of which redirect our attention to the possibility of movement: whether
of a stratum itself in bending or buckling, or of materials seeping through
from one layer to another. Yet far from resolving the problem of solid
fluidity, the focus on movement recasts it in another form. Do we under-
stand movement disjointedly, as the successive displacement and re-
attachment of solid bodies, or as a process of fluid deformation? Here
we rediscover in archaeology the same controversy that we have already
encountered in glaciology and in the astronomical study of nebulae.
These questions, as Lucas shows, can be traced back to the celebrated
paradox of motion originally set forth by Zeno in the 5th century BCE. If
the trajectory of a solid body, like an arrow in flight, can be resolved into
an infinite series of fixed points, then how can it move at all? In our fifth
contribution, Cris Simonetti returns to Zeno’s paradox, and to the alter-
native view of movement – attributed to Heraclitus – as the fluid deform-
ation of a continuous and heterogeneous material. Central to Simonetti’s
discussion is the concept of viscosity. From John Locke’s understanding
that solidity underpins our very sense of what is real in the world,
through William Wordsworth’s appeal to ‘the solid ground of Nature’,
20 Theory, Culture & Society 0(0)
to contemporary appeals to hard science, the default assumption of the
solidity of matter is a deep-rooted and persistent theme of modern
thought. From this perspective, the condition of viscosity shows up as
an anomaly. Stickiness offends the alleged human propensity to order the
material world into discrete categories. Focusing on the case of glacial
ice, Simonetti shows that ice’s viscosity, already an issue in the afore-
mentioned dispute between Forbes and Tyndall, continues to trouble our
understandings of glaciers and how they move. Time and again, ice has
been opposed to soil: the former inert, homogeneous and barren; the
latter active, heterogeneous and fertile. But we now know that ice is as
heterogeneous as soil, and that it is packed with micro-organisms. Could
viscous ice be a reservoir of life itself? And is organic life only possible
thanks to the fundamental viscosity of all matter?
For some answers to these questions, we turn to our next contribution,
from environmental sociologist Bronislaw Szerszynski. Szerszynski’s
focus is on colloids, and his approach is fundamentally rheological.
Starting from the assumption that all matter is continuous, Szerszynski
argues that colloids are intermediate in scale: neither macroscopic nor
microscopic but mesoscopic, on the mezzanine floor of matter, so to
speak. But they are intermediate in the other sense as well, for in them,
continuous matter folds in on itself so as to form an intricate topology of
surfaces by which particles appear separated from the medium of their
suspension. Colloidal materials, then, are constitutionally in the midst,
formed of the interior crumpling and knotting of their own medium. No
grain, droplet or pore can ever be alone, since it exists only thanks to a
cascade of repetitions that rebound throughout the entire mass. Thus the
very condition of existence of particles in colloidal suspension is to be
with one another. For that reason, Szerszynski argues, colloids provide a
powerful model for thinking about the social. It is not that social life is a
condition only reached on approach to humanity; on the contrary – in
this view – sociality is a constitutive quality of all matter in its colloidal
condition. As much as bubbles of air in a liquid foam, we humans, too,
are formed through the iterative infolding of the medium; only for us, the
medium is an atmosphere. This is to understand social phenomena nei-
ther as compound effects of individual interactions, nor as their sub-
sumption under a totalising, solidary whole, but in terms of the
rheological dynamics of colloidal substance.
One way to distinguish relative solidity from relative fluidity is by
materials’ capacity to remember or forget. Elastic materials, under
stress, preserve the memory of their initial configuration in the tension
of their molecular bonds, which allows them to revert to form once the
tension is relaxed. Plastic materials, by contrast, release the energy of
deformation as heat, remembering nothing of their previous shape. But
colloids – as Szerszynski shows – neither fully remember nor fully forget,
confounding the distinction between the two. Material memories,
Ingold and Simonetti 21
however, can inhere not only in inter-molecular bonds but also in the
nuclear core of matter itself. In our penultimate contribution, geohuma-
nities scholar Sasha Engelmann explores the mnemonic capacities of
materials in greater depth through a focus on the detritus of thermo-
nuclear explosions. Every such explosion involves a phase transition so
rapid that to our human senses it appears over in a few seconds. In the
composition of radioactive glasses and minerals the moment of transition
is, as it were, frozen in time. Yet these substances remain unstable, caught
in a process of decay over earthly timescales vastly in excess of human
lifespans. In what Engelmann calls their ‘elemental memory’, radioactive
materials both register the singularity of atomic events and problematise
the constructs of time on which our usual distinctions between solid and
fluid – and correspondingly between remembering and forgetting – are
based. To investigate this tension, between the virtual instantaneity of the
atomic event and the long-drawn-out process of radioactive decay,
Engelmann introduces us to the work of artists Mari Keto and Erich
Berger, who have made it their practice to forge jewellery from radio-
active minerals.
Now if, with Engelmann, we take memory to be a constituent property
of the material world, brought to a focus in human minds yet not con-
tained in them, might we argue, more generally, that the achievements of
humanity – its civilisations and industries – likewise bring to a focus
geophysical forces and processes operating on a planetary scale? This,
in essence, is what critical geographer Nigel Clark argues in the final
contribution of this collection. Throughout the history of our planet,
oceanic and riverine sediment has settled and compacted to form solid
strata, while volcanic eruptions, and the seepage of magma into cracks
and crevices, have left us with expanses and intrusions of hard, igneous
rock. But the irrigation works that supported the growth of ancient,
urban civilisations did no more than continue age-old sedimentary pro-
cess under new management, while the pyrotechnic arts of pottery, brick-
making and metallurgy likewise concentrated igneous processes of earth-
formation in the heart of the city, made safe within the protective shell of
the kiln. Where pottery and brickmaking replicated the heat-induced
formation of metamorphic rock from sediment, the metallurgist would
reproduce in the furnace the very conditions of the magma chamber
whence metal-bearing, igneous rocks were once born. In short, the city,
far from being walled off as an island of civilisation against the rest of the
globe, can be better understood as a place of intensification, where
planetary geopower is concentrated and reproduced in the human
domain. But with our cities inundated by floodwater and forests
ablaze, have the same hydrological and igneous forces that once fuelled
the growth of civilisation now turned against us?
We are certainly faced today with formidable challenges. If these
explorations on the boundary between solidity and fluidity have taught
22 Theory, Culture & Society 0(0)
us anything, it is that we will have to find ways to live with planetary
forces, not against them. But we have also learned that in the long run of
history, this is what human beings have always done. The Anthropocene
is popularly presented as the epoch in which humans finally became the
dominant force in shaping the conditions of the planet. But if this really
is a new epoch, it is only just beginning. We have no idea how it will turn
out. Perhaps, after all, it will prove to be a period of rediscovery, in which
we eventually develop the necessary skills for living with a solid fluid
planet much altered by millennia of previous activity.
Acknowledgements
The articles making up this special issue were first presented and discussed at the work-
shop ‘Solid Fluids: New Approaches to Matter and Meaning’, held in August 2018 at the
University of Aberdeen, as part of the four-year project (2015–19) ‘Solid Fluids in the
Anthropocene’, funded by the British Academy under its International Partnership and
Mobility Scheme (for more information, see www.solidfluids.org). We are grateful to the
Academy for its support, and to all the workshop participants, including several who –
for different reasons – were unable to contribute to this collection. They include Mike
Anusas, Matt Edgeworth, Enrico Marcore, Elishka Stirton and Judith Winter. We also
thank the editors of Theory, Culture & Society for their encouragement, and three ano-
nymous reviewers for their generous comments.
ORCID iDs
Tim Ingold https://orcid.org/0000-0001-6703-6137
Cristia
´n Simonetti https://orcid.org/0000-0002-0755-3332
Notes
1. From an interview with Michel Serres, conducted in 2009 by Roberto Leo
Butinof, Adria
´n Cangi and Ariel Pennisi.
2. A handbook by the 15th-century painter Piero della Francesca instructs mer-
chants in the art of gauging the volume of a barrel. As the art historian
Michael Baxandall shows, Piero’s mercantile public, observing his
Madonna del Parto of c.1460, depicting the pregnant Madonna in a pavilion
shaped like a half-barrel, would have immediately set about estimating its
volume (Baxandall, 1972: 87–8).
3. Precisely because he imagines an environment furnished with solids, psych-
ologist James Gibson – in his ecological approach to visual perception – ends
up depicting gaps in the tree canopy as holes: ‘it is into these holes that the
birds fly’ (Gibson, 1986: 106). But birds cannot fly in holes. They fly in the
air, setting it in motion with the beating of their wings (Ingold, 2011: 127).
4. See Kenneth Change, ‘The nature of glass remains anything but clear’, New
York Times, 29 July 2008, https://www.nytimes.com/2008/07/29/science/
29glass.html.
5. Art historian Barbara Baert (2020: 42) notes that the word ‘marble’ is derived
from the Sanskrit root mar, connoting movement, as of the waves of the sea,
‘and may have contributed to the idea that marble is water metamorphosed
into stone’.
Ingold and Simonetti 23
6. Starch in water (or ‘corn-starch’) is an example of what is known technically
as a ‘non-Newtonian fluid’, in that it does not conform to Newton’s law,
according to which viscosity is a constant, independent of the rate of flow.
In non-Newtonian liquids the amplification of flow, such as by stirring, can
either reduce or increase viscosity. With corn-starch, viscosity in increased.
Shaking ketchup in a bottle, however, makes it runnier (Szerszynski, this
issue).
7. Landscape architects Anuradha Madha and Dilip da Cunha (2014), for
example, argue that instead of blaming floods on inadequate drainage, we
should take what they call the ‘wealth of wetness’, of land ubiquitously
saturated by rainfall, as an invitation to build differently.
8. From the Book of Judges, Chapter 5, verse 5.
9. These lines are taken from the new English translation of Le
´vi-Strauss’s La
pense
´e sauvage, first published in French in 1962. An earlier translation
appeared in 1966 under the title The Savage Mind.
10. Whitehead set out his views on science in his Lowell lectures of 1925, Science
and the Modern World. A year later, in a series of lectures entitled Religion in
the Making, he attempted to apply the same ideas to religion that he had
previously applied to science (Whitehead, 1926, 1929).
11. Though Bergson and Whitehead both adhered to a philosophy of process,
Whitehead (1929) would not have agreed with Bergson’s view that the ten-
dency to solidify is intrinsic to all human intellection. For Whitehead, it was
rather specific to a culture of the intellect that emerged in the 17th century
and went on to dominate science.
12. Elsewhere, one of us (Simonetti, 2019b) has aligned this distinction with a
contrast, respectively, between imaginative and chronographic attitudes, spe-
cifically in the discipline of geology. To adopt the former is to enter, in the
imagination, into the processes of earth formation and to go along with
them; to adopt the latter is to cast a retrospective eye over the stages of
this history, already petrified in strata of rock, and to order them in chrono-
logical sequence. For an equivalent contrast in archaeology, see Lucas (this
issue).
13. It is possible that in writing these lines Blake was influenced by the vortex
theory of planetary motion advanced by Rene
´Descartes, according to which
the planets ride the rings of an immense cosmic vortex whirling around the
sun. The theory remained popular and influential until the mid-18th cen-
tury, when it eventually fell to the Newtonian theory of gravitational
attraction.
14. This is to paraphrase the rather more longwinded formulation of the same
point by Deleuze and Guattari (2004: 400–1).
15. See https://delta.phil-fak.uni-koeln.de/.
References
Baert, Barbara (2020) The Weeping Rock: Revisiting Niobe through Paragone,
Pathosformel and Petrification (Studies in Iconology 17). Leuven: Peeters.
Baxandall, Michael (1972) Painting and Experience in Fifteenth Century Italy: A
Primer in the Social History of Pictorial Style. Oxford: Oxford University
Press.
24 Theory, Culture & Society 0(0)
Bergson, Henri (1911) Creative Evolution, trans. Arthur Mitchell. London:
Macmillan.
Blake, William (1907) Milton, eds. Eric Robert Dalrymple Maclagan and
Archibald George Blomefield Russell. London: A.H. Bullen.
Brand, Stewart (1994) How Buildings Learn: What Happens to Them after
They’re Built. New York: Penguin.
Clark, Nigel (forthcoming) Planetary cities: Fluid rock foundations of civiliza-
tion. Theory, Culture & Society.
Cruikshank, Julie (2005) Do Glaciers Listen? Vancouver: University of British
Columbia Press.
Deleuze, Gilles (1993) The Fold: Leibniz and the Baroque, trans. Tom Conley.
London: Athlone.
Deleuze, Gilles and Guattari, Fe
´lix (2004) A Thousand Plateaus: Capitalism and
Schizophrenia, trans. Brian Massumi. London: Continuum.
Edgeworth, R., Dalton B.J. and Parnell, Thomas (1984) The pitch drop experi-
ment. European Journal of Physics 5(4): 198–200.
Engelmann, Sasha (forthcoming) Elemental memory: The solid fluidity of the
elements in the nuclear era. Theory, Culture & Society.
Gibson, James J. (1986) The Ecological Approach to Visual Perception. Hillsdale,
NJ: Lawrence Erlbaum.
Gruppuso, Paolo (forthcoming) In-between solidity and fluidity: the reclaimed
marshlands of Agro Pontino. Theory, Culture & Society.
Hutton, James (1795) Theory of the Earth with Proofs and Illustrations, Vols I &
II. Edinburgh: William Creech.
Ingold, Tim (1992) Culture and the perception of the environment. In: Croll,
Elizabeth and Parkin, David (eds) Bush Base: Forest Farm. Culture,
Environment and Development. London: Routledge.
Ingold, Tim (2011) Being Alive: Essays on Movement, Knowledge and
Description. Abingdon: Routledge.
Ingold, Tim (2015) The Life of Lines. Abingdon: Routledge.
Ingold, Tim (2016) Evolution and Social Life (new edition). Abingdon:
Routledge.
Ingold, Tim (2020) In the gathering shadows of material things. In: Schorch,
Philipp, Saxer, Martin and Elders, Marlen (eds) Exploring Materiality and
Connectivity in Anthropology and Beyond. London: UCL Press.
Ingold, Tim and Hallam, Elizabeth (2007) Creativity and cultural improvisation:
An introduction. In: Hallam, Elizabeth and Ingold, Tim (eds) Creativity and
Cultural Improvisation. Oxford: Berg.
Krause, Franz (forthcoming) The tempo of solid fluids: On river ice, permafrost,
and other melting matter in the Mackenzie Delta. Theory, Culture & Society.
Le
´vi-Strauss, Claude (2020) Wild Thought, trans. Jeffrey Mehlman and John
Leavitt. Chicago, IL: University of Chicago Press.
Lucas, Gavin (forthcoming) Archaeological stratigraphy and the bifurcation of
time: Solido intra solidum.Theory, Culture & Society.
Lucretius Carus, Titus (2007) The Nature of Things, trans. Alicia Elsbeth
Stallings, intro. Richard Jenkyns. London: Penguin.
Madha, Anuradha and da Cunha, Dilip (2014) Design in the Terrain of Water.
Novato, CA: ORO Editions/Applied Research and Design.
Ingold and Simonetti 25
Marx, Karl (1930 [1890]) Capital,Volume 1, trans. Eden and Cedar Paul from
the 4th German Edition of Das Kapital. London: Dent.
Massey, Doreen (2005) For Space. London: SAGE.
Merleau-Ponty, Maurice (1964) Eye and mind, trans. Carleton Dallery. In: Edie,
James M. (ed.) The Primacy of Perception, and Other Essays on
Phenomenological Psychology, the Philosophy of Art, History and Politics.
Evanston, IL: Northwestern University Press.
Meulemans, Germain (forthcoming) Solidifying grounds: The intricate art of
foundation building. Theory, Culture & Society.
Nasim, Omar W. (2013) Observing by Hand: Sketching the Nebulae in the
Nineteenth Century. Chicago, IL: University of Chicago Press.
Ruskin, John (2004) Selected Writings, ed. and intro. Dinah Birch. Oxford:
Oxford University Press.
Serres, Michel (2000) The Birth of Physics, trans. Jack Hawkes. Manchester:
Clinamen Press.
Simonetti, Cristia
´n (2019a) Weathering climate: Telescoping change. Journal of
the Royal Anthropological Institute (N.S.) 25: 241–264.
Simonetti, Cristia
´n (2019b) The petrified Anthropocene. Theory, Culture &
Society 36: 45–66.
Simonetti, Cristia
´n (forthcoming) Viscosity in matter, life and sociality: The case
of glacial ice. Theory, Culture & Society.
Simonetti, Cristia
´n and Ingold, Tim (2018) Ice and concrete: Solid fluids of
environmental change. Journal of Contemporary Archaeology 5: 19–31.
Steno, Nicolaus (1916 [1669]) The Prodromus of Nicolaus Steno’s Dissertation,
Concerning a Solid Body Enclosed by Processes of Nature Within a Solid,
trans. John Garrett Winter. New York: Macmillan.
Szerszynski, Bronislaw (forthcoming) Colloidal social theory: Thinking about
material animacy and sociality beyond solids and fluids. Theory, Culture &
Society.
Tonna, Sandra, Ruggieri, Nicola and Chesi, Claudio (2018) Comparison
between two traditional earthquake-proof solutions: Borbone and Lefkada
timber-frame systems. Journal of Architectural Engineering 24(4): 04018030.
Walters, Kenneth (2010) History of rheology. In: Lorenzano, Pablo,
Rheinberger, Hans-Jyrg, Ortiz, Eduardo and Galles, Carlos Delfino (eds)
History and Philosophy of Science and Technology, Vol. III. UNESCO:
Encyclopedia of Life Support Systems.
Whitehead, Alfred North (1926) Religion in the Making: Lowell Lectures 1926.
Cambridge: Cambridge University Press.
Whitehead, Alfred North (1929) Science and the Modern World: Lowell Lectures
1925. Cambridge: Cambridge University Press.
Zanotto, Edgar Dutra (1998) Do cathedral glasses flow? American Journal of
Physics 66: 392–395.
Tim Ingold is Professor Emeritus of Social Anthropology at the
University of Aberdeen. He has written on environment, technology
and social organisation in the circumpolar North, on animals in
human society, and on human ecology and evolutionary theory. His
more recent work explores environmental perception and skilled practice.
26 Theory, Culture & Society 0(0)
Ingold’s current interests lie on the interface between anthropology,
archaeology, art and architecture. His recent books include The
Perception of the Environment (2000), Lines (2007), Being Alive (2011),
Making (2013), The Life of Lines (2015), Anthropology and/as Education
(2018), Anthropology: Why it Matters (2018) and Correspondences (2020).
Cristia
´n Simonetti is Associate Professor in Anthropology at the
Pontificia Universidad Cato
´lica de Chile. His work has concentrated
on how bodily gestures and environmental forces relate to notions of
time in science. More recently he has engaged in collaborations across
the sciences, arts and humanities to explore the environmental properties
of solid fluid materials relevant to the Anthropocene. He is the author of
Sentient Conceptualizations: Feeling for Time in the Sciences of the Past
(2018) and co-editor of Surfaces: Transformations of Body, Materials and
Earth (2020).
This article is part of the Theory, Culture & Society special issue on ‘Solid
Fluids: New Approaches to Materials and Meaning’, edited by Tim Ingold
and Cristia
´n Simonetti.
Ingold and Simonetti 27
