← All mental models

Reusable cognitive primitives

Stocks and flows

A stock is an amount that accumulates; flows are the rates that add to or drain it. The stock changes only when inflow and outflow differ.

Where it appears

Dependencies & synergies

Derived from the graph’s real structure — 37 concepts across 43 disciplines carry this pattern. Every figure is a count, not a score.

Reach across disciplines

How many concepts carrying this pattern are seen through each discipline.

Patterns that travel with it

Other thinking patterns that recur on the same concepts — the more shared concepts, the more often they co-occur.

The shape of its reasoning

What kinds of relationships the carrying concepts form — the relational signature of the pattern.

  • Kind & structure65 edges
  • Cause & effect38 edges
  • Dependency33 edges
  • Teaching link17 edges
  • Analogy & transfer10 edges
  • Explains & models5 edges
Furthest-reaching carriers

Concepts where this pattern does the most cross-disciplinary work — each reaches disciplines beyond its own.

  • Energy transferreachesAcousticsAgricultureBiochemistryBiophysicsCell BiologyChemistryEcologyEconomicsEnvironmental ScienceMechanical EngineeringMechanicsOceanographyOpticsOrganic ChemistryPhysiologyPolitical EconomyPolitical PhilosophySociologyStatistical PhysicsSustainability ScienceSystems BiologyThermodynamics
  • PhotosynthesisreachesAgricultural EngineeringBotanyCell BiologyEcologyEconomicsEngineeringEnvironmental EngineeringEnvironmental ScienceGeographyGeologyMarine BiologyMicrobiologyNutrition ScienceOceanographyOrganic ChemistryPhysicsSustainability Science
  • CyclereachesChemistryClimatologyCognitive ScienceDesignEcologyEconomicsEducationEducational ScienceEnvironmental ScienceGeographyGeologyMachine LearningMathematicsMechanicsSustainability Science
  • EnergyreachesAstronomyBiologyChemistryEarth & Space SciencesEnergy EngineeringEngineeringEnvironmental EngineeringMechanical EngineeringMechanicsNutrition SciencePlasma PhysicsThermodynamics
  • MetabolismreachesArchitectureBioinformaticsBiophysicsChemical EngineeringChemistryEngineeringEnvironmental EngineeringGeometryMathematicsMicrobiologyPhysics
  • SystemreachesAtmospheric ScienceComplexity ScienceEconomicsEnvironmental ScienceGeographyHuman-Computer InteractionMathematicsMeteorologyPhysicsSociologySystems Biology

Foundation of the pattern

Carrying concepts that others in the same pattern build on (they depend on or follow from these).

  1. Carbon dioxide (CO₂) 1 other concept build on it
  2. Convection 1 other concept build on it
  3. Energy 1 other concept build on it

Examples across disciplines

Geography

Atmospheric CO₂ is a stock; photosynthesis drains it and respiration and burning fill it.

Economics

A country's food supply is a stock fed by production and drained by consumption.

How this pattern travels

Interpreted from where the pattern recurs in the atlas — structural transfer and coverage, not a claim it is universally the "best" model.

  • Recurs across 43 disciplines over 37 carrier concepts — a broadly transferable pattern.

    structural · Structural recurrence in the atlas — a pattern is a reasoning lens, not a law.

  • 18 of its 37 carrier concepts are themselves cross-disciplinary connectors.

    structural · Structural recurrence in the atlas — a pattern is a reasoning lens, not a law.

  • Explicit "where it breaks" notes exist for 1 of 3 annotated assignments.

    curated · Curated boundary annotations — absence is a representation gap, not evidence the model has no limits.

  • Currently dark in the atlas: no origin recorded.

    atlas representation · Describes the current Thinking OS representation, not the model itself.

Coverage matrix

How these concepts distribute across domains and concept families — real counts, not a score.

SystemsInformationMatterChangePatternsEnergyLifeScaleStructureDecisionNetworksWavesCausalityComputationEarthSpaceOptimizationNumberProbabilitySecurityThresholdsConstraintsNatural sciencesFormal sciencesEngineeringMedicine & healthSocial sciencesHumanitiesProfessionalArtsInterdisciplinary12251221113

The statistical fingerprint

How the 37 concepts that exercise this pattern distribute — from the graph, not a ranking.

Disciplinary fingerprint

Carrier concepts under each illuminating lens.

How settled its carriers are

Epistemic status of the concepts that exercise this pattern.

  • Established37 · 100%

Where the model breaks

This pattern is a reasoning lens, not a law. Here is where it stops helping:

  • Biodegradation (mechanism): Stock-and-flow accounting tracks the level and rates, but not the microbial kinetics or the persistent fraction that never degrades on human timescales.

1 of 3 explained assignments cite a source; the rest are editorial interpretations. None is externally validated.

Common misconception

That a large inflow always means a rising stock — it only rises if inflow exceeds outflow.

Journeys where it shows up

Try a transfer challenge

You have seen this model in one place. Where else could it apply — and where would the analogy break?

Carbon cycle
The intuition

Think of a bathtub: the water level (stock) rises or falls depending on the tap (inflow) and the drain (outflow).

The reach of this pattern
  • Recurs across 43 disciplines.
  • 108 concepts exercise this thinking pattern.
  • 1 of them explicitly note where the model breaks down.
  • It is practised in 2 learning journeys.

Derived from the graph — a pattern is a reasoning lens, not a law.

How to recognise it

Is what you are watching a level that accumulates or a rate that fills and drains it — and would the level keep rising even as the inflow slows?

Keep this question handy when you meet something new — it helps you notice the pattern, not just name it.