Thermodynamics and Evolution Explained

The Claim and Why It Sounds Plausible

The argument arrives dressed in the language of hard science, and that is its chief rhetorical virtue. Evolution, the creationist insists, violates the second law of thermodynamics. Complexity cannot increase spontaneously within a system governed by entropy. Order cannot arise from disorder. Physics itself stands in the way. Therefore a designer must have arranged the living world, because nature, left to its own devices, can only decay. The argument has circulated in creationist literature for decades, appearing in pamphlets, in debates, in YouTube comment sections, and on the floor of American state legislatures. It is repeated with a confidence that implies the speaker has the textbooks firmly on their side.

The textbooks say no such thing. The argument fails at its very first step, and it fails not because of some subtle philosophical objection or because the evidence for evolution is too vast to dismiss in a single essay, but because it misrepresents the second law of thermodynamics in a way that any first-year physics student would recognise as elementary. The law does not say what the creationist claims it says. The condition under which the law operates, a genuinely isolated system, does not apply to Earth, which receives an enormous and continuous energy input from the Sun. Once that single fact is grasped, the thermodynamic objection to evolution dissolves entirely, and what remains in its place is not a scientific argument but a theological preference wearing borrowed scientific clothing.

This essay works through the physics with enough care to show precisely where the creationist argument goes wrong, considers the examples that demonstrate local decreases in entropy happening throughout nature every day, examines the mechanism of natural selection as a complexity-building process, and then asks the harder question: if the argument is this straightforwardly mistaken, why does it persist, and what does its persistence tell us about the relationship between religious commitment and scientific reasoning? The claim being tested here is specific: that the second law of thermodynamics constitutes a genuine scientific refutation of biological evolution, requiring the invocation of a designer to account for the complexity of living things. That claim is false, and the following sections explain in detail why it is false.

1. What the Second Law Actually Says

The second law of thermodynamics is one of the most fundamental and well-confirmed principles in all of physics. In its most general statement, it says that the total entropy of an isolated system will tend to increase over time, or at least will never decrease. Entropy, loosely speaking, is a measure of the number of ways a system’s energy can be distributed among its microscopic components. A highly ordered arrangement, atoms in a precise crystal lattice for instance, corresponds to a low number of possible microscopic distributions and therefore to low entropy. A disordered arrangement, the same atoms scattered randomly as a gas, corresponds to a vastly larger number of possible distributions and therefore to high entropy. Systems tend toward the latter because there are simply more ways to be disordered than to be ordered, and random processes are more likely to land the system in a common configuration than in a rare one.

This principle is robustly confirmed by everything from the behaviour of steam engines to the physics of black holes. Nothing in evolutionary biology disputes it. What is in dispute, and what the creationist consistently misrepresents, is the domain of the law’s application. The second law applies to isolated systems, meaning systems that exchange neither energy nor matter with their surroundings. The classic thought experiment is a perfectly insulated box, sealed from the universe, within which no energy enters or leaves. Within such a box, entropy can only increase or remain the same. Organised complexity cannot spontaneously arise from simplicity, because there is no source of energy to drive the process.

The critical word is “isolated,” and the creationist argument depends entirely on pretending that word is not there. Most real systems in the universe are not isolated. They are open systems, meaning they exchange energy, matter, or both with their environments. The second law, properly stated and applied to open systems, says something quite different: the total entropy of the universe, the system plus its surroundings combined, must increase or remain the same. Within an open system, however, entropy can decrease locally, provided that the process responsible for that decrease exports a larger quantity of entropy to the surroundings. Local order can arise, local complexity can increase, without violating the second law in the slightest, as long as the thermodynamic books balance across the whole universe.

This is not a loophole introduced to protect a theory that would otherwise collapse. It is not a special pleading invented to rescue Darwin from the physicists. It is the standard thermodynamics taught in every undergraduate physics course, written into every relevant textbook, applied in every relevant branch of engineering and chemistry. The creationist argument, to be direct about it, is not engaging with the science. It is engaging with a caricature of the science, one that strips the law of its essential qualifying condition and then applies the stripped version to a domain where it was never intended to apply.

2. Earth Is an Open System, and the Sun Is the Reason

Earth is not an isolated system, and this is the central and decisive fact that dismantles the thermodynamic objection to evolution entirely. Every day, the Sun pours approximately 1.74 times ten to the power of seventeen watts of electromagnetic radiation onto Earth’s surface. That is a number so large it resists intuition until you begin cataloguing what it actually drives. It drives the differential heating of the atmosphere that produces global weather systems. It drives the thermohaline circulation of the world’s oceans, moving enormous volumes of water across planetary distances. It drives the water cycle, lifting billions of tonnes of water into the atmosphere and redistributing it across continents. Above all, it drives photosynthesis, which captures solar energy and uses it to build complex organic molecules from simple inorganic ones, carbon dioxide and water, creating the energetic foundation on which all animal life depends.

Earth also radiates energy back into space, in the form of infrared radiation. The planet is, in thermodynamic terms, a flow-through system. Energy arrives in a high-quality, low-entropy form as visible light from the Sun, does work as it cascades through the biosphere, and is eventually radiated away as lower-quality, higher-entropy heat. It is this flow of energy, from a hot source to a cold sink, that powers every organised process on Earth, including every biological process. The entropy increase associated with that energy flow is more than sufficient to account for the local decreases in entropy that biological organisation represents. The universe’s entropy budget is honoured in full. Nothing is cheated, and nothing is borrowed from outside the natural order.

A useful analogy, though analogies always carry limitations, is a refrigerator. A refrigerator creates a zone of low temperature and low entropy inside its cabinet, in apparent defiance of intuitions about disorder increasing. No physicist loses sleep over the refrigerator, because the refrigerator is plugged into the mains. It pumps entropy from its interior into the kitchen, and the power station that drives it releases far more entropy into the atmosphere than the appliance removes from its contents. The total entropy of the universe increases. The local decrease inside the cabinet is real, it is produced by ordinary physics, and it violates nothing. Biological evolution operates on precisely the same logic: the Sun is the mains supply, the biosphere is the cabinet, and the heat radiated into space is the entropy exported to the surroundings. There is no violation and no mystery requiring supernatural resolution.

The creationist argument, then, is precisely equivalent to pointing at a plugged-in refrigerator and declaring that it refutes thermodynamics. The error is not subtle. It is the error of ignoring the context in which a physical law operates, and it is an error that the creationist commits not through unfamiliarity with thermodynamics but, given how long the refutation has been in print, through a motivated attachment to the conclusion the error makes possible.

3. Local Entropy Decreases Happen Everywhere in Nature

If the second law truly forbade increases in local complexity and organisation, then a great deal more than evolution would be in serious trouble. The creationist who deploys the thermodynamic argument against biology has, perhaps without fully appreciating the consequence, committed to a position that is refuted by some of the most familiar and beautiful phenomena in the natural world, phenomena that nobody attributes to divine intervention.

A snowflake is a structure of extraordinary geometric complexity, a six-fold symmetrical crystal built from water molecules arranging themselves into precise lattice positions according to the quantum mechanical properties of the hydrogen bond. The formation of a snowflake represents a local decrease in entropy: disordered water vapour becomes ordered crystalline ice. Nobody, as far as is known, has proposed a designer for the snowflake. Nobody has argued that each of the estimated ten thousand trillion snowflakes that fall on Earth every year required supernatural intervention to achieve their symmetry. The explanation is thermodynamic: the formation of the crystal releases latent heat into the surrounding air, increasing the entropy of the surroundings by more than the entropy of the snowflake decreases. The total entropy of the universe increases. The local order is real, it is produced by physics, and it violates nothing.

Consider also the formation of a salt crystal from a supersaturated solution. Sodium and chloride ions, chaotically distributed in water, spontaneously arrange themselves into a precise cubic lattice when conditions allow. The entropy of the crystal is lower than the entropy of the dissolved ions, but the heat released in the process increases the entropy of the surrounding solution by a greater amount. Again, the law is satisfied. Again, order arises from disorder through a perfectly mundane physical process, driven by the tendency of systems to move toward lower energy states, with the entropy cost paid by the surroundings. The process requires no intelligence, no prior specification, no intervention from outside the natural order.

Consider a developing embryo. A fertilised egg, a single cell of extraordinary but finite complexity, undergoes a process of differentiation and growth that produces, over nine months, an organism of staggering structural elaboration: trillions of cells, hundreds of distinct cell types, tissues, organs, a nervous system capable of abstract thought and self-reflection. This represents an enormous local decrease in entropy. Nobody argues that embryological development requires a miracle at each cell division. The energy driving that development comes from the biochemical processing of nutrients, which are themselves products of photosynthesis, which is itself driven by solar energy. The entropy exported in the form of metabolic heat more than compensates for the entropy decrease represented by the growing organism. The second law is satisfied at every step, without exception and without remainder.

The examples extend almost indefinitely. Every whirlpool in a river is a local decrease in entropy driven by the flow of water down a gravitational gradient. Every flame is a region of highly organised chemical reactions driven by the release of chemical bond energy. Every living cell is a zone of extraordinary molecular organisation maintained by a continuous throughput of energy derived ultimately from sunlight. The universe is saturated with local order, local complexity, and local decreases in entropy, all of them perfectly consistent with the second law because all of them are open systems embedded in a larger context that absorbs the thermodynamic cost. Biological evolution is not an exception to this pattern. It is one of its most elaborate instances.

4. Natural Selection as a Complexity-Building Mechanism

Even if the thermodynamic objection were somehow valid at the level of physics, it would still fail to engage with the actual mechanism by which biological complexity increases over evolutionary time. Natural selection is not a process that randomly assembles complex structures from simple components in a single step, which is the implicit and deeply misleading model the thermodynamic argument assumes. It is a cumulative process, operating over vast stretches of geological time, in which small, heritable variations are filtered by the differential survival and reproduction of the organisms that carry them. Beneficial variations accumulate across generations. Harmful ones are removed from the population. Complexity builds incrementally, each step building on the last, each step energetically plausible, none of them requiring a spontaneous leap from disorder to elaborate order.

This distinction is central to understanding why the thermodynamic objection misses its target entirely. When a creationist imagines evolution as the equivalent of a tornado assembling a Boeing 747 from the components of a scrapyard, which is Fred Hoyle’s famous but thoroughly misleading analogy, they are imagining a single-step process in which enormous complexity arises from nothing in an instant. That would indeed be thermodynamically improbable to the point of practical impossibility. But that picture has nothing to do with evolution. Evolution is a multi-step process in which each step is small, each step is energetically driven, and each step is preserved by selection before the next step begins. The complexity is real, but it is built incrementally over hundreds of millions of years, powered at every stage by solar energy cascading through the biosphere, and preserved at every stage by the filtering action of natural selection on heritable variation.

Daniel Dennett’s framework of cranes and skyhooks is useful here. In his account of Darwin’s contribution to philosophy, Dennett distinguishes between what he calls “skyhooks,” explanatory devices that appeal to some top-down, mind-first force descending from outside the natural order, and “cranes,” mechanisms that are themselves products of prior processes and that can demonstrably lift the complexity of outcomes step by step without external assistance. Natural selection is the canonical crane. It requires no external input of information from a designer, no violation of any physical law, and no appeal to any force operating outside the natural order. Given sufficient time, energy, and heritable variation, it will predictably produce biological complexity from simpler beginnings, because that is what the mathematics of differential reproduction over time guarantees it will do.

The energetics of natural selection are well understood at every level of biological organisation. At the molecular level, the replication of DNA, the synthesis of proteins, and the maintenance of cellular organisation all require energy, and all obtain it from the biochemical processing of molecules whose energy content is ultimately derived from sunlight captured by photosynthesis. At the population level, the differential reproduction of organisms is driven by access to energy-rich resources, food, light, and chemical gradients, that are themselves products of energy flows through the biosphere. At no level does the process run free of the thermodynamic constraints that govern all chemistry and physics. It operates entirely within those constraints, exploiting them rather than defying them, building complexity through the patient accumulation of energetically favoured steps rather than through any single miraculous transition.

The cumulative nature of the process is worth dwelling on, because it is the feature most consistently obscured by creationist presentations. When a creationist asks how a bacterial flagellum could possibly have assembled itself from its component parts, they are framing the question in a way that assumes simultaneous assembly of all components, as though the flagellum had to arise fully formed from a pile of molecular parts that had no prior function. But that is not how evolution works, and it is not what the biology shows. Each component of the flagellum has evolutionary relatives with independent functions in other biological contexts. The Type Three Secretion System, a molecular pump found in many bacteria, shares several protein components with the flagellum and almost certainly predates it evolutionarily. The evolutionary history of complex structures is a history of co-option, modification, and gradual elaboration, not spontaneous assembly, and that history is entirely consistent with thermodynamics, because each step is energetically driven and each intermediate form is a functional organism powered by the same solar energy flow that powers everything else in the biosphere.

5. The History of the Argument and Its Persistence

The thermodynamic argument against evolution is not new, and its longevity is itself revealing. It has been circulating in creationist literature since at least the 1970s, when Henry Morris and Duane Gish of the Institute for Creation Research began deploying it systematically in public debates. Morris held an engineering doctorate and therefore had genuine familiarity with thermodynamics. He was presumably aware that the second law applies to isolated systems and that Earth is not one. The argument’s persistence in creationist circles after it was thoroughly refuted by physicists and biologists in peer-reviewed literature suggests that its appeal is not primarily scientific but rhetorical. It uses the authority of physics to cast doubt on biology, and it does so in language technical enough to intimidate non-specialists while remaining vague enough to evade precise refutation within the limited format of a public debate.

The physicist Jeffrey Wicken addressed the argument in rigorous detail in the 1980s, demonstrating that biological self-organisation is not merely thermodynamically permitted but thermodynamically expected in systems far from equilibrium that are subject to a continuous energy flow. Ilya Prigogine’s Nobel Prize-winning work on dissipative structures in the 1970s had already established the theoretical framework within which biological organisation makes complete thermodynamic sense. Prigogine showed that systems driven far from thermodynamic equilibrium by continuous energy flows can spontaneously develop organised, complex structures, which he termed dissipative structures, that are maintained by the ongoing throughput of energy rather than by any violation of physical law. A living cell is a dissipative structure. An ecosystem is a dissipative structure. The biosphere as a whole is a dissipative structure. All of them are consistent with the second law. All of them are ultimately powered by the Sun.

Despite this, the thermodynamic objection continues to circulate, in the same form, with the same errors, in creationist materials produced decades after the refutation was established in the scientific literature. This is not how scientific arguments behave. When a scientific claim is refuted by evidence and analysis, scientists revise or abandon it, sometimes reluctantly, but eventually. When a creationist argument is refuted by evidence and analysis, it is repeated at the next debate, reprinted in the next pamphlet, and taught to the next generation of Sunday school students as though the refutation had never been published. This is the behaviour of motivated reasoning, not of scientific inquiry, and it tells us something important about the epistemic standards governing the enterprise from which the argument emerges.

Carl Sagan observed, with characteristic clarity: “Evolving before our eyes has been a God of the Gaps; that is, whatever it is we cannot explain lately is attributed to God.” The thermodynamic argument is a God of the Gaps argument in formal scientific dress. It identifies what its proponents believe to be a gap in naturalistic explanation, the apparent increase in biological complexity over evolutionary time, and inserts a designer into that gap as the required solution. The gap, however, is not real. It is produced by a misreading of thermodynamics, and once the misreading is corrected, the space for the designer disappears. The argument provides no positive evidence for design. It provides evidence only that its proponents have not read the relevant thermodynamics carefully, or have read it and chosen to misrepresent it for an audience unlikely to check the source.

The sociology of the argument’s persistence matters here. The Institute for Creation Research, Answers in Genesis, and their institutional descendants are not organisations that function as scientific bodies. They are organisations whose stated purpose is the defence of a particular reading of scripture against any empirical challenge. Their publications undergo no peer review by independent specialists. Their arguments are not revised in response to the published refutations of scientists working in the relevant fields. Their audiences are communities whose trust in those organisations is grounded in shared religious commitment rather than in the organisations’ track record of accurate scientific prediction. Within those communities, the thermodynamic argument is encountered first and most authoritatively, usually in a simplified and technically inaccessible form, and the refutation, when encountered at all, is framed as part of a broader secular conspiracy against religious truth. This is the ecosystem in which the argument survives, and its survival is entirely a product of that ecosystem rather than of any residual scientific merit.

6. The Irreducible Complexity Overlay

The thermodynamic argument is often deployed alongside, and sometimes conflated with, the argument from irreducible complexity, most prominently associated with Michael Behe’s 1996 book Darwin’s Black Box. Behe argued that certain biological structures, the bacterial flagellum being his most famous example, are composed of multiple interacting parts such that the removal of any single part renders the structure non-functional. Such structures, he claimed, could not have evolved by natural selection because each intermediate stage in their construction would be non-functional and therefore would confer no selective advantage. A structure that cannot work until all its parts are simultaneously in place, the argument goes, cannot be built one part at a time by a process that can only preserve what works at each step.

The argument from irreducible complexity and the thermodynamic argument share a common logical structure, even though they draw on different scientific domains. Both assume that natural processes cannot account for the biological complexity we observe without supernatural assistance, and both fail because they misrepresent the processes they invoke. The irreducible complexity argument fails because, as Kenneth Miller and others have demonstrated at length, the components of allegedly irreducibly complex structures have evolutionary precursors with independent functions. The parts of the bacterial flagellum are homologous to the components of the Type Three Secretion System, a molecular pump that functions independently of the flagellum and that almost certainly predated it evolutionarily. The flagellum is not irreducibly complex in the sense Behe requires. Its complexity is fully reducible, given a sufficiently detailed account of its evolutionary history, which molecular biology has now substantially provided.

The thermodynamic argument fails for the reason already established: it misapplies the second law to a system that does not meet the law’s conditions of application. The two arguments, however, reinforce each other rhetorically in creationist discourse, creating the impression that evolution faces objections from multiple independent scientific domains simultaneously. That impression is a rhetorical construction rather than a scientific reality. Neither argument represents a genuine scientific challenge to evolutionary theory. Both represent the same underlying strategy: dress a theological preference in scientific vocabulary, claim that the science supports what revelation already requires, and rely on the technical language being sufficient to discourage close examination by a general audience.

You can read more about this strategy and the specific claims of the intelligent design movement in the essay on the cult of complexity and intelligent design on this site, which addresses Behe’s argument and its successors at considerably greater length. The present essay is concerned with the thermodynamic version of the objection specifically, but the two belong to the same family of arguments and are defeated by the same general principle: appeals to apparent complexity in nature are not evidence for design when the natural processes that produce complexity are already well understood and thermodynamically unproblematic.

7. The Designer Does Not Solve the Problem

There is a further problem with the thermodynamic argument that its proponents rarely consider, because it is a problem that cuts against their preferred conclusion rather than against evolution. If the second law of thermodynamics truly forbade the increase of biological complexity through natural processes, it would forbid it regardless of whether the mechanism of increase was natural selection or supernatural design. A designer who assembles complex biological structures is, from the thermodynamic perspective, doing work. That work requires energy, and that energy must come from somewhere. Wherever it originates, the entropy of the universe must increase as a consequence of its expenditure. A supernatural designer does not receive a thermodynamic exemption by virtue of being supernatural. If the second law genuinely forbade complexity-generating processes, it would forbid the designer’s activity just as surely as it would forbid natural selection’s activity.

The creationist might respond that the designer operates outside the natural order and is therefore not subject to thermodynamic constraints. But this response concedes the entire argument. If the designer operates outside the natural order, then the designer cannot legitimately be invoked as a scientific explanation for anything within the natural order, because science is precisely and by definition the investigation of natural processes by natural means. An entity outside nature, operating by mechanisms outside physics, is not a scientific hypothesis. It is a theological assertion, and theological assertions are not scientific alternatives to evolutionary theory. They belong to a different domain of discourse entirely, one that has no special authority over the empirical question of how biological complexity arose on this planet.

Richard Dawkins made this point with characteristic precision: “If we want to postulate a deity capable of engineering all the organized complexity in the world, either instantaneously or by guiding evolution, that deity must have been vastly complex in the first place. The creationist, whether a naive Bible-thumper or an educated bishop, simply postulates an already existing being of prodigious intelligence and complexity. If we are going to allow ourselves the luxury of postulating organized complexity without offering an explanation, we might as well make a job of it and simply postulate the existence of life as we know it!” The force of this observation is exact and worth dwelling on. The appeal to a designer does not explain biological complexity. It relocates it, positing an entity whose own complexity is at least as great as the complexity it is supposed to explain, and leaving that entity’s origins and organisation entirely unaccounted for. From a thermodynamic perspective, this is not a solution to the problem. It is a restatement of the problem at a greater level of abstraction, and a particularly unsatisfying one, because the designer’s complexity is simply asserted rather than explained.

The honest intellectual position is that natural selection, operating over billions of years in an open system continuously supplied with solar energy, provides an account of the increase in biological complexity that is consistent with all relevant physics, including thermodynamics. The designer, by contrast, provides no account at all. It provides a name for the mystery without illuminating it, a placeholder for ignorance dressed in the language of solution. As an intellectual move, that is the opposite of progress, and the second law of thermodynamics, correctly understood, provides no support for it whatsoever.

8. Why the Argument Appeals Despite Its Failure

Understanding why the thermodynamic argument fails is, as the preceding sections have shown, a relatively straightforward exercise in applied physics. Understanding why it continues to persuade a significant number of people requires a different kind of analysis, one that attends to the psychology of belief and the sociology of creationist movements rather than to the specifics of entropy and open systems.

The argument’s rhetorical appeal rests on several features that are independent of its scientific validity. First, and most importantly, it uses the language of established physics, a domain of science widely perceived as among the most rigorous and reliable, to attack biology, which is the domain of science most threatening to certain religious commitments. If physics can be made to appear to refute biology, then the person committed to rejecting evolution for theological reasons acquires a tool that sounds more authoritative than scripture and more respectable than simple disbelief. The argument borrows the credibility of thermodynamics while systematically misrepresenting what thermodynamics actually says. This is not an accident of poor communication. It is the argument’s core rhetorical strategy.

Second, the argument exploits a genuine and not entirely unreasonable intuition that most people carry from everyday experience. In ordinary life, things do tend to fall apart rather than come together without effort. Houses require maintenance to resist decay. Cars rust when left untended. Organisations become less efficient over time without active management. Bodies age and deteriorate through the decades. The intuition that order is fragile and that disorder is the natural tendency of unattended systems is not baseless. It reflects a genuine asymmetry in the world that the second law captures at the level of statistical mechanics. The creationist argument takes this genuine everyday intuition and extends it, without justification, to domains where it does not apply, persuading people that what feels true in ordinary experience must also be true of biological evolution operating over geological timescales in an energy-rich open system. This is the kind of reasoning from unexamined intuition to physical law that has historically produced flat-earth cosmology and geocentric astronomy. Intuition is a starting point for inquiry, not a substitute for measurement and inference.

Third, the argument is essentially evasive in the context of popular debate. When a scientist responds that Earth is an open system, the creationist can simply deny the relevance of this fact, or claim that the energy input from the Sun is insufficient to drive the required increase in biological information, or shift to a different variant of the argument that emphasises information content rather than entropy in the physical sense. The argument is modular and difficult to pin down in a format that does not allow sustained technical exchange. Each of its components can be quietly replaced when challenged without the core assertion, that evolution violates some fundamental physical principle, ever being formally abandoned. This is the characteristic behaviour of a position defended by motivated reasoning rather than by commitment to evidence.

The argument is also, in practical terms, asymmetric in the time and effort it takes to deploy versus refute. Stating that the second law forbids the increase of biological complexity requires one sentence in a debate, one paragraph in a pamphlet, one slide in a PowerPoint presentation. Refuting it correctly requires explaining isolated versus open systems, the role of solar energy input, the mechanism of dissipative structures, and the cumulative rather than instantaneous nature of natural selection. In a format with equal time for each speaker, the refutation always takes longer than the assertion, which means the creationist argument will always appear more confident and the scientific response will always appear more laboured. This asymmetry is not accidental. It is a feature of the argument as a rhetorical weapon rather than as a scientific contribution, and it works regardless of which side has the better physics behind it.

9. The Information Variant of the Argument

In more sophisticated creationist circles, particularly those associated with the intelligent design movement rather than with young-earth creationism, the thermodynamic argument has been partially replaced by a related argument about biological information. The claim is that biological complexity represents not merely physical order but specified, functional information of the kind encoded in DNA, and that the second law, properly extended to the domain of information theory, forbids the spontaneous increase of such information without the involvement of an intelligent source. The information, the argument goes, had to come from somewhere, and the only known source of specified information is a mind.

This variant, associated primarily with the mathematician and philosopher William Dembski, has a more technically elaborate apparatus than the simple thermodynamic objection. Dembski introduced the concept of “specified complexity” as a measure of the kind of information that cannot, he argued, be generated by chance and necessity alone. Biological structures exhibit specified complexity, therefore, he concluded, they must have been designed. The argument has a surface rigour that the original thermodynamic version lacks. Beneath the surface, however, it fails for closely related reasons. Dembski’s concept of “specified complexity” is not a standard concept in information theory as practised by working scientists and mathematicians. His claim that natural processes cannot generate specified complexity has been challenged on both conceptual and empirical grounds by information theorists, biologists, and philosophers of science, and the challenges have not been adequately answered within the intelligent design literature.

The deeper problem is that the information-theoretic argument essentially defines the kind of complexity it is concerned with as the kind that can only be produced by intelligence, and then argues that because biological structures exhibit this kind of complexity, they must have been produced by intelligence. The circularity is not always immediately obvious, because the argument is couched in mathematical notation that makes it appear more rigorous than it is. But when the definitions are unpacked carefully, as critics from David Wolpert to Wesley Elsberry have done in the scientific literature, the circularity becomes apparent. The argument assumes its conclusion in the construction of its central concept and therefore proves nothing that was not already assumed.

Furthermore, the information-theoretic argument faces the same open-system objection that defeats the thermodynamic argument. Information, in the Shannon sense in which it can be given a precise and mathematically tractable definition, is not conserved in open systems in the manner the intelligent design argument requires. The information content of a biological system can increase through mutation and selection operating in an energy-rich environment without violating any principle of information theory, for the same reason that the local entropy of a developing embryo can decrease without violating the second law. The system is open, the broader context absorbs the relevant costs, and the process is entirely natural. Dressing the thermodynamic argument in information-theoretic clothing does not rescue it from the fundamental error. It makes the error slightly more difficult to identify for non-specialists, which may well be the point, but it does not change the error’s nature.

Those interested in the broader family of intelligent design arguments, including the information-theoretic versions, will find further analysis at the discussion of pseudo-science and the evidence of god on this site, which addresses the standards of evidence that genuine scientific claims must meet and that theistic arguments consistently fail to satisfy.

10. What Honest Engagement with the Physics Requires

The thermodynamic argument against evolution is not a case where reasonable people disagree about the interpretation of ambiguous evidence. It is a case where one side has misrepresented an established physical law and drawn a conclusion from that misrepresentation that the actual physics does not support. Charitable engagement with the argument requires that this be stated plainly and without unnecessary qualification. To treat the thermodynamic objection to evolution as a legitimate scientific controversy, deserving of equal time and respectful equivocation from science educators and communicators, is not intellectual balance. It is a failure of intellectual honesty, the kind of false symmetry that would treat the flat-earth position as equally deserving of consideration alongside the spherical-earth position on the grounds that both deserve a hearing.

What honest engagement requires, on the creationist side, is a willingness to read the thermodynamics correctly. The second law applies to isolated systems. Earth is not an isolated system. The Sun provides a massive and continuous energy input that is more than sufficient to power the local decreases in entropy that biological organisation represents. These are not contested claims at the frontier of scientific knowledge. They are standard physics, available in every relevant textbook, confirmed by every relevant measurement, and taught in every relevant undergraduate course. A creationist who continues to deploy the thermodynamic argument after genuinely understanding these facts is not making a scientific argument. They are making a choice to misrepresent science in the service of a theological conclusion, and that choice deserves to be identified for precisely what it is.

What honest engagement requires on the science communication side is the willingness to explain the physics accessibly and without condescension, to distinguish clearly between the genuine difficulty of some open questions in evolutionary biology and the complete non-difficulty of the thermodynamic objection, which is not a hard question at all once the relevant concepts are correctly in place, and to resist the temptation to treat an argument’s persistence as evidence that it has merit. An argument does not become more credible by being repeated across decades and generations. It becomes more insistent, and insistence is a property of the rhetorician committed to a conclusion, not of the scientist following the evidence.

The wider context belongs here as well. The thermodynamic argument against evolution is one instance of a broader and well-documented pattern in which scientific-sounding objections are constructed to give theological commitments the appearance of empirical support. This pattern has been analysed in detail in the scientific and philosophical literature on creationism and intelligent design, and the consistent finding is that none of these objections, once examined against the actual science they claim to invoke, represent genuine challenges to evolutionary theory. They represent challenges to the public understanding of science, and meeting those challenges requires clear, patient, and accurate explanation of what the relevant science actually demonstrates, rather than a diplomatic pretence that the challenges are more scientifically serious than they are.

11. The Broader Stakes

None of this would matter greatly if the thermodynamic argument against evolution were merely an academic curiosity, a philosophical puzzle confined to seminar rooms and published refutations in specialist journals. It is not confined there. It is an argument deployed in live educational policy debates, in courtrooms, in school board meetings, and in the religious instruction of children who will grow up to be doctors, engineers, biologists, and citizens who vote on questions of science policy. The creationist movement in the United States has, at various points and in various states, succeeded in inserting “teach the controversy” provisions into science education standards, provisions that implicitly treat the thermodynamic objection and arguments like it as legitimate scientific alternatives to the overwhelming consensus of physics and biology. The damage done to science education by these provisions is real, measurable, and long-lasting.

A student who leaves secondary school believing that thermodynamics refutes evolution has been miseducated in both subjects simultaneously. They have been given a false picture of how the physical world works, and that false picture has been presented to them under the banner of intellectual balance and critical thinking, two values that are, in this context, being systematically inverted. Genuine critical thinking about the thermodynamic argument against evolution leads directly and quickly to the conclusion that the argument is wrong. Presenting it as a credible scientific alternative to the consensus of two centuries of biological and physical research is not critical thinking. It is indoctrination carried out through the rhetorical appropriation of critical thinking’s vocabulary.

The harm of miseducating students about thermodynamics and evolution goes beyond the specific errors involved in the thermodynamic argument itself. It teaches a more general and more corrosive epistemological lesson: that scientific consensus can be legitimately overturned by sufficiently confident assertion of a scientific-sounding objection, even when that objection has been repeatedly and thoroughly refuted by specialists in the relevant fields. This lesson, once internalised, does not stay confined to the question of evolution. It extends naturally to other questions where the motivated rejection of scientific consensus carries serious real-world consequences: questions about the human contribution to climate change, about the safety and efficacy of vaccines, about the age of the universe, about the origins of the cosmos. The epistemological habits that creationist science education cultivates are not merely wrong about evolution. They are corrosive to the capacity for evidence-based reasoning across the board, and the thermodynamic argument is one of the primary tools used to establish those habits in young minds before they have the scientific background to evaluate it for themselves.

None of this is a comment on the character of the individuals who repeat the thermodynamic argument in good faith. The vast majority of them are neither malicious nor intellectually incompetent. They are people who have been told, by authorities they trust within communities they belong to, that evolution is a serious threat to their understanding of human dignity, divine purpose, and moral order, and that physics supports that assessment. They have been given incorrect information about thermodynamics by people they had reason to trust, and they have passed it on in good faith. The argument’s proponents in positions of institutional leadership, those who understand the thermodynamics and choose to misrepresent it for strategic purposes anyway, bear a qualitatively different and considerably greater moral responsibility for the miseducation that results. The ordinary believer who repeats the argument sincerely is not the object of this critique. The argument itself is, and the institutions that propagate it are, and those are the appropriate targets of sustained intellectual challenge.

12. The Question of Information and the Origin of Life

A related but distinct version of the thermodynamic challenge concerns not the evolution of existing life but the origin of life from non-living chemistry, the question of abiogenesis. Creationists sometimes argue that even if evolution could be reconciled with thermodynamics once life exists, the original emergence of self-replicating chemistry from an inorganic world represents an increase in organised complexity so vast and so improbable that no thermodynamic accounting can accommodate it. The leap from simple organic molecules to a self-replicating RNA strand, they argue, is the real challenge, and no amount of solar energy can explain how the chemistry got started.

The question of the origin of life is genuinely harder than the question of subsequent evolution, and intellectual honesty requires saying so plainly. The mechanism by which self-replicating chemistry first arose on the early Earth is not fully understood. Several plausible scenarios have been developed, including the RNA world hypothesis, hydrothermal vent chemistry, and the mineral surface theories associated with Graham Cairns-Smith, but none of them amounts to a complete and experimentally verified account of how life began. This is an open research question in chemistry and biology, and the scientists who work on it are the first to acknowledge its difficulty.

None of this, however, restores the thermodynamic objection to scientific respectability. The fact that the precise mechanism of abiogenesis is not yet fully understood does not mean that the process violated thermodynamics, any more than the fact that we cannot fully reconstruct the specific chemical conditions of the early Earth means that those conditions were physically impossible. The early Earth was an open system, receiving solar energy and possessing steep chemical and thermal gradients, particularly around hydrothermal vents, that provided exactly the kind of energy flow required to drive the formation of complex organic molecules. Laboratory experiments have demonstrated that amino acids, nucleobases, and other biologically relevant molecules form spontaneously under conditions plausibly similar to those of the early Earth, as the Miller-Urey experiment demonstrated in 1953 and as subsequent work by many researchers has confirmed and extended. The chemistry is hard, the specifics remain uncertain, but the thermodynamics are not obstructed.

The creationist who points to the origin of life as a thermodynamic impossibility is, once again, treating an open scientific question as though its openness were evidence for a supernatural solution. The question is not, therefore a designer. The question is, what were the specific chemical pathways, and that question is one for chemistry and biology to answer through experiment and inference. The designer is no help here either, because positing an intelligent agent who arranged the first self-replicating molecule simply restates the problem of complex specified chemistry at a higher level of abstraction and then declines to explain the mechanism. The honest response to an unanswered scientific question is continued scientific investigation, not the premature insertion of a supernatural explanation that explains nothing and forecloses further inquiry.

Conclusion: The Physics Is Clear and the Verdict Is Plain

The second law of thermodynamics does not disprove evolution. It does not challenge evolution in any technically serious way. It does not even inconvenience evolutionary theory at any point in its well-established account of the history of life. The claim that it does rests entirely on a misrepresentation of the law’s domain of application, specifically the requirement that the system under consideration be isolated from its surroundings, and on a systematic failure to account for the enormous and continuous energy input that the Sun provides to Earth every day. Once those two facts are correctly incorporated into the analysis, the thermodynamic objection to evolution disappears without remainder.

Local decreases in entropy happen throughout the natural world, all around us and continuously. They occur in snowflakes and salt crystals, in growing embryos and developing storms, in every living cell and every ecosystem on Earth. None of them violate the second law. All of them are thermodynamically paid for by the entropy exported to their surroundings. Evolution is the same process operating over geological time with natural selection as the mechanism that preserves and accumulates energetically favoured outcomes. There is no physical mystery at the heart of biological complexity, and there is no gap in the physics wide enough to accommodate a designer, because the thermodynamic argument that was supposed to open that gap rests on a misreading of the very law it invokes.

The argument’s persistence tells us nothing about the state of the physics and a great deal about the sociology of creationist movements, which are structured to defend predetermined conclusions against the evidence rather than to revise conclusions in response to it. That is the honest assessment of what the thermodynamic argument against evolution represents: not a scientific objection arising from genuine engagement with the relevant physics, but a rhetorical device dressed in borrowed technical clothing, deployed in the service of a conclusion that was reached long before the argument was assembled to support it. The physics was never consulted in good faith. It was conscripted into service after the verdict was already in.

Science can afford to be patient with this. The second law is not threatened by its misappropriation in creationist literature. The law will remain exactly what it is, applying exactly where it applies, long after every pamphlet misrepresenting it has been pulped. But the public understanding of both thermodynamics and evolutionary biology is threatened by the argument’s continued circulation, and the students taught this misinformation in the name of balance will carry the resulting misconceptions into their adult lives and into their assessments of the world. That cost is worth naming, worth resisting, and worth explaining clearly, accurately, and without the false modesty that treats a thoroughly refuted argument as deserving of continued scientific respect simply because the people who advance it are sincere.

Does Physics Actually Disprove Evolution?