The universe trends toward disorder. Something pushes back. We call it knowledge. The pushback works through a particular kind of object: tools — knowledge taken out of a mind and given a physical form that another body can pick up and use.
A tool is the moment knowledge stops being a state of someone’s brain and becomes a state of the world. Before the tool, knowledge has to be re-derived by every person who needs it. After the tool, knowledge persists, travels, and can be activated by anyone who knows how to hold it. A hand axe sitting in the soil of Venerque is half a million years of accumulated understanding about fracture mechanics, grip ergonomics, and edge geometry — frozen in stone, available to whoever picks it up. The knowledge that took thousands of generations to acquire is now usable in an afternoon.
This is the simplest and most consequential observation in the philosophy of technology: a tool is knowledge made physical, made usable, made inheritable. The argument of this piece is that this fact — together with the loop it enables — is what civilization actually runs on.
In previous pieces we established what knowledge is: neg-entropic structure with causal power, a physical configuration of matter that creates further configurations that would be astronomically improbable without it. This piece asks the next question: how does that knowledge move from a brain into the world, and how does the world process it from there? What operations must any system perform on knowledge to wield it? And do those operations depend on being human, or only on being physical?
The physics of processing knowledge
Room-scale computation: when Landauer proved that erasing a single bit costs energy, these were the machines doing the erasing. Cognition is thermodynamics, whether the substrate fills a room or fits in a skull. (NASA)
Before we talk about tools or intelligence, we need to establish something that most discussions of cognition ignore: processing knowledge is a physical act with irreducible physical costs.
In 1961, Rolf Landauer at IBM proved that erasing one bit of information, flipping a memory register from an unknown state to a known zero, must dissipate at least kBT ln 2 of energy as heat. At room temperature, that’s about 2.9 × 10⁻²¹ joules. Tiny, but irreducible. You cannot erase information for free. The universe charges a tax. The principle was experimentally confirmed in 2012, when a team led by Antoine Bérut measured the heat produced by erasing a single bit and found it matched Landauer’s minimum exactly.
Landauer’s conclusion, stated with characteristic bluntness: information “is always tied to a physical representation” and “is not a disembodied abstract entity.”
Why does this matter for tools? Because every cognitive operation — every act of encoding experience into a reusable pattern, every retrieval of stored knowledge, every activation of a plan — is a physical process that transforms matter and dissipates energy. A brain running at 20 watts, a Mesopotamian scribe carving a tablet, a data center running at megawatts: all are physical engines processing knowledge against a background of entropy. A tool, by giving knowledge a physical form, is what allows that processing to happen outside a single nervous system. Tools are the substrate that makes knowledge transferable.
John Wheeler, the Princeton physicist who coined “black hole” and “wormhole,” pushed this to its logical extreme with his “It from Bit” hypothesis (1989): physical reality itself may emerge from information, every particle and field deriving its existence from binary choices. The holographic principle lent stunning support: the maximum information content of any region of space is bounded by its boundary area, and Einstein’s equations can be derived from information-theoretic constraints. At the deepest level physics can currently reach, information appears to be more fundamental than spacetime.
This is the ground on which a serious account of tools must stand. We are talking about a physical process, with physical costs, operating on a physical substrate. With that established, we can ask: what does that process actually do?
The three operations
Here is the mental model. Hold it up to any intelligent system, biological or artificial, individual or collective, and it will illuminate what that system is doing.
Intelligence is a system’s capacity to perform three operations on knowledge: encode raw experience into reusable patterns, retrieve the right pattern at the right time, and activate it to produce results in the world.
Encode
The biological encoding engine: billions of connections shaped by experience, encoding patterns so deeply that retrieval feels like instinct. (Wikimedia Commons)
The first operation is encoding: turning raw, abundant, noisy experience into compact, reusable patterns.
This is what learning is. A child who encounters thousands of four-legged, furry, barking creatures and forms the concept “dog” has encoded a vast sensory manifold into a single retrievable category. A physicist who derives F=ma has encoded the behavior of every moving object in the universe into three symbols. A craftsperson who develops an intuition for when wood is “ready” to be carved has encoded years of tactile experience into a felt sense that guides action without conscious deliberation.
This is what François Chollet calls skill-acquisition efficiency: how much generalization a system gains per unit of experience. A system that needs a million examples to learn a category is encoding poorly. One that grasps it from three is encoding well. The ratio of insight to data is the signature of intelligence.
And encoding has physical costs. Landauer showed that every erasure dissipates heat. Every act of encoding — discarding the inessential, retaining the essential — is a thermodynamic transaction. The brain burns glucose to encode experience into memories. A training run burns megawatt-hours to encode a corpus into model weights. Encoding is work, measured in joules as surely as lifting a stone.
Daniel Kahneman’s dual process theory maps directly onto this. System 1 is a library of pre-encoded patterns: heuristics, intuitions, automatic responses, built up over a lifetime of experience and, before that, over millions of years of evolution. When you catch a ball, recognize a face, or sense danger in a dark alley, System 1 is activating encoded knowledge so fast that it feels like instinct. System 2 is the encoder itself: the slow, effortful, deliberate process of constructing new patterns from novel situations. When you solve a math problem, plan a vacation, or learn a new language, System 2 is doing the encoding work that will eventually become System 1’s effortless retrieval.
John Robert Anderson’s ACT-R cognitive architecture formalizes this at a finer grain. In ACT-R, cognition consists of two interacting memory systems: declarative memory (encoded facts, stored as “chunks”) and procedural memory (encoded rules for acting on facts, stored as “productions”). Every cognitive act, from solving algebra to navigating a conversation, decomposes into retrieving a chunk of declarative knowledge and applying a procedural rule to it. The architecture has been validated against hundreds of psychological experiments and maps onto specific brain regions identified through fMRI. Encoding, in ACT-R, is the process by which experience is distilled into chunks and productions that can be rapidly retrieved and deployed.
Retrieve
The second operation is retrieval: accessing the right encoded pattern at the right time in the right context.
Having knowledge is useless if you cannot find it when you need it. The most brilliant insight ever encoded into a neural pattern is worthless if it surfaces during the wrong task, or fails to surface at all. Retrieval is the mechanism by which encoded knowledge becomes available for action.
Allan Collins and Elizabeth Loftus’s spreading activation theory (1975) describes how retrieval works in biological cognition. Memory is organized as a network of interconnected nodes. Activating one node sends energy rippling outward to related ones. “Doctor” activates “nurse” faster than “bread” because the two nodes are tightly linked through shared associations. The closer two concepts sit in the network, the faster and stronger the activation spreads.
The deeper question is what these nodes actually are. Knowledge is not stored in discrete locations. It is distributed across patterns of connection weights, configurations of activation spread across thousands of units. There is no single place in your brain that “stores” the concept of a dog. The concept is the pattern. David Rumelhart and James McClelland’s work on parallel distributed processing established this: knowledge is a pattern that emerges from connections between simple units working in parallel. Any system with the right connection patterns could in principle retrieve and represent knowledge, whether or not it is made of biological neurons.
This architecture has a deep consequence: retrieval is associative and context-sensitive, governed by proximity in a network of meaning rather than by alphabetical filing or logical indexing. You remember a song because you smell the perfume you were wearing when you first heard it. You solve a physics problem because its structure reminds you of a water-flow analogy you encountered years ago. The retrieval mechanism is pattern-matching over a vast landscape of encoded experience, and the quality of retrieval depends on the richness of the connections between encoded patterns.
Dedre Gentner’s structure-mapping theory (1983) shows that retrieval is also the mechanism of analogy and creative insight. When a scientist sees the atom as a solar system, she is retrieving an encoded pattern from one domain (planetary orbits) and mapping its relational structure onto another (electron behavior). The objects are different; the relationships are the same. Creativity, in this framework, is retrieval across domains: finding encoded patterns in unexpected places and recognizing that their structure fits a new problem.
Activate
The third operation is activation: deploying retrieved knowledge to resolve uncertainty and produce results in the world.
This is where intelligence meets reality. Encoding creates the arsenal. Retrieval selects the weapon. Activation fires it. A surgeon activating anatomical knowledge to perform an operation. An engineer activating structural knowledge to design a bridge. A diplomat activating knowledge of cultural norms to negotiate a treaty. A farmer activating knowledge of seasons and soil to plant a crop. This is what Michael Hochberg’s Theory of Intelligences formalizes: intelligence as the resolution of uncertainty producing a result or goal. The framework is substrate-independent: it describes what activation does, regardless of what it’s made of.
Activation never happens in a vacuum. It extends through tools, bodies, and environments. Andy Clark and David Chalmers argued in “The Extended Mind” that the boundary of cognition is not the skull; it is wherever the cognitive work gets done. When a surgeon activates knowledge through a scalpel, or a programmer through a compiler, the tool is part of the activation. Lucy Suchman’s research on situated action showed that activation is always improvised in context, shaped by material and social circumstances rather than merely executing a pre-formed plan. Knowledge activates somewhere, through something, in response to something specific.
And activation distributes. Edwin Hutchins studied how a U.S. Navy ship’s navigation team brings a vessel into port (Cognition in the Wild). No single crew member holds the full picture. One reads a bearing, another plots it, a third integrates bearings to fix position. The computation is distributed across people, instruments, and protocols. The team is the cognitive system. Hutchins showed the team possesses cognitive properties — error detection and information integration — that no individual member has. Activation at scale is always distributed cognition.
It is the step where individual cognition and collective civilization connect, because the activation of knowledge almost always involves tools.
Tools: knowledge made physical, made usable
Half a million years of accumulated knowledge about fracture mechanics, grip ergonomics, and edge geometry, encoded into stone. The hand axe is a theory of materials science that predates language. (MHNT / Wikimedia Commons)
Here is the pivot. The most consequential single move in the history of intelligence is the move that turns knowledge — a state of someone’s brain — into an object that anyone can pick up.
A tool is knowledge given a physical body, made usable by someone who did not originate it, made inheritable across generations. A hand axe is encoded knowledge of fracture mechanics, materialized into stone. A book is encoded knowledge of a domain, materialized into text. A bridge is encoded knowledge of structural engineering, materialized into steel and concrete. A programming language is encoded knowledge of computation, materialized into syntax. A thermostat is encoded knowledge of feedback control, materialized into bimetallic strips and switches. A search index is encoded knowledge of the web’s content, materialized into a directed graph of links. In every case the same thing is happening: a configuration of matter holds a pattern that, once externalized, no longer depends on any single mind to remain available.
Ernst Kapp recognized this in 1877. In Elements of a Philosophy of Technology, he proposed that every tool is an unconscious projection of a human organ: the hammer projects the fist, the lens projects the eye, the telegraph projects the nervous system. Each projection externalizes biological knowledge into a form that can be inspected, improved, and inherited. André Leroi-Gourhan traced the full evolutionary trajectory: muscular knowledge externalized into levers and engines, memorial knowledge externalized into writing and libraries, reasoning knowledge externalized into calculation and computation. The trajectory is one continuous movement: more of what was once inside a body, becoming part of the world the body inhabits.
Arnold Gehlen, the German philosophical anthropologist, explained why this trajectory is necessary. In his 1940 work Der Mensch, Gehlen described humans as Mängelwesen: deficient beings, biologically unspecialized, lacking fur, claws, speed, and reliable instincts. This deficiency is what compels tool-making. Because we cannot adapt our bodies to environments, we adapt environments to our bodies through tools. Gehlen’s key concept, Entlastung (relief or unburdening), captures the cognitive function of tools precisely: they relieve the mind of routine processing, freeing cognitive capacity for higher-order encoding and activation. The calculator relieves arithmetic. The calendar relieves temporal memory. The map relieves spatial reasoning. Each tool absorbs a cognitive function that the biological brain can then redeploy elsewhere.
Memorial knowledge encoded into movable type. Each letter block is a unit of reusable, transmissible knowledge. The press democratized retrieval. (Wikimedia Commons)
The critical feature of tools is that they enable activation without full comprehension. You can use a calculator without understanding transistor physics. You can take an antibiotic without understanding pharmacology. You can drive a car without understanding combustion. Tools encode the knowledge of their creators into a form that allows others to activate it. This is what makes them civilizationally powerful: they democratize activation while concentrating the burden of encoding among specialists. A few people learn how to manufacture penicillin; a billion people use it. A few people learn how to build a search engine; three billion query it. The asymmetry between the cost of encoding and the cost of activation is the lever that lifts whole civilizations.
Kim Sterelny calls this cognitive niche construction: each generation inherits a world of tools (encoded knowledge) and institutions (organized retrieval and activation systems) that scaffold the intelligence of the next. The cognitive niche is a distributed knowledge system. And it is what made the human species extraordinary: individually, we are Gehlen’s deficient beings, cognitively limited by biological constraints; collectively, embedded in a cognitive niche of tools, symbols, and institutions, we are the most powerful knowledge-processing system the universe has produced.
The headline claim of this piece sits exactly here. A tool is the physical, usable embodiment of knowledge — and the architecture of civilization is the architecture of how tools accumulate. Every other claim in the series is downstream of this one.
The intelligence of civilizations
Retrieval infrastructure at civilizational scale: two hundred thousand encoded patterns, organized for access, maintained across centuries. The Library of Alexandria was a retrieval system. So is this. So is Google Scholar. (Diliff / Wikimedia Commons)
The encode / retrieve / activate model scales. Apply it to a single human mind and you see Kahneman’s System 1 and System 2, Anderson’s ACT-R, Collins and Loftus’s spreading activation. Apply it to a civilization and you see something structurally identical operating at a vastly larger scale, run by the accumulated stock of tools.
At civilizational scale, the same loop runs through different equipment. Science and law encode centuries of observation and conflict into theory and precedent, libraries and search engines retrieve those patterns when they are needed, and factories, hospitals, and courtrooms put them to work.
The power of human civilization is that these three operations run in a loop. Activation produces new experience. New experience gets encoded into new knowledge. New knowledge gets stored in retrievable form. Retrieval makes it available for further activation. The loop turns, and the cognitive niche gets richer with each revolution. And every revolution of the loop produces new tools, which embody the newly encoded knowledge in physical form, ready for the next generation to retrieve and activate without having to derive it again. The speed at which the loop turns determines the speed at which civilization moves. The depth of the toolstack determines how far each generation can travel without re-discovering what is already known.
A small number of foundational tools have done the deepest work of running this loop at planetary scale. They are not the only tools that matter. They are the ones whose presence reshaped what every other tool could do. They are the subject of the next piece in this series.
Closure
David Deutsch described this loop from a different angle in The Beginning of Infinity. The vocabulary differs. The structure does not. What Deutsch foregrounds is creative conjecture, the capacity to generate explanations that go beyond existing data, subject them to criticism, and retain those that survive.
For most of human history, this was an exclusively human capacity. Only human minds could conjecture, criticize, and encode. Only human hands — augmented by the tools they had built — could activate. The loop ran through us and only through us. The tools were our instruments. We were the cognitive actor-seekers — entities that seek goals by acting on knowledge, wielding the encode / retrieve / activate loop as their fundamental operating principle.
The criteria restated
The cognitive niche, visible from space. Every point of light is encoded knowledge being activated: power grids, cities, networks, the accumulated encode / retrieve / activate infrastructure of human civilization glowing against the dark. (NASA/NOAA)
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Now step back and see what the model reveals.
We have defined a tool as the physical, usable embodiment of knowledge — the moment information stops being a state of someone’s brain and becomes a state of the world. We have defined intelligence as a system’s capacity to encode information into reusable knowledge, retrieve the right pattern at the right moment, and activate it to produce results in the world. We have shown that the cognitive niche — humanity’s accumulated ecology of tools and institutions — runs these operations at civilizational scale, and that the loop turning is what produces history. We have grounded all of this in physics: every cognitive operation is a thermodynamic transaction.
We have a name for systems that meet these criteria: systems that encode information into retrievable knowledge, expand and update that knowledge through error-correction, and activate it into world-impacting action. We call them cognitive actor-seekers — entities that seek goals by acting on knowledge, wielding the encode / retrieve / activate loop as their fundamental operating principle.
For billions of years, the only cognitive actor-seekers were biological organisms. For hundreds of thousands of years, human culture extended their reach through tools and language. For a few centuries, scientific institutions supercharged the loop through conjecture and criticism. The arc has been one continuous movement of knowledge from inside bodies to inside the world — from the hand axe to the codex to the power grid to the search index.
A new kind of cognitive actor-seeker is now being constructed. It is not, strictly, a tool we pick up and use. It is something stranger: a tool that runs the loop itself, that encodes and retrieves and activates on its own, that arrives across every layer of the cognitive niche at the same time. What it is, and what it changes, is the subject of the world-building piece. Before we can speak about it usefully, we have to look at the tools that came before — the small number of foundational technologies that have run the encode / retrieve / activate loop at civilizational scale, each one faster than the last. That is the subject of the next piece in this series.
The thing that fights the dark has acquired a new form. The gap between the word and the world is about to close. Tracing how — through which tools, on which substrate, with which institutional consequences — is the work the rest of the series will do.
This is the first piece in the Evolutionary Tools series. It establishes what a tool is — knowledge made physical, made usable, made inheritable — and the three-operation loop (encode / retrieve / activate) that all intelligent systems run. The next piece walks five foundational tools (writing, maps, electricity, the computer, the search engine) through the seven-layer civilizational stack. The world-building piece develops the sixth case: foundation models and the new kind of cognitive actor-seeker they instantiate.
The encode / retrieve / activate framework sits inside the broader frame Deutsch develops in The Beginning of Infinity, and synthesizes Hochberg’s Theory of Intelligences, Chollet’s On the Measure of Intelligence, Anderson’s ACT-R architecture, Collins and Loftus’s spreading activation theory, and Sterelny’s The Evolved Apprentice. For the foundations the argument leans on, see the Infinite Knowledge series: Two Types of Entropies and The Thing That Fights the Dark.