Tuesday, October 18, 2011

Water Is Not H2O

It is a straightforward fact, although corrections to it are endlessly ignored, that it is simply false to say that water is H2O unless we are speaking very, very loosely. I've mentioned this before, pointing to Michael Weisberg's paper, Water is Not H2O (PDF) and summarizing van Brakel's "Chemistry as the Science of the Transformation of Substances," but I notice that Holly VandeWall puts it very nicely in her paper, "Why Water Is Not H2O, and Other Critiques of Essentialist Ontology from the Philosophy of Chemistry," in Philosophy of Science vol. 74, no. 5 (December 2007):

An individual molecule of H2O doesn’t have any of the observable properties we associate with water. A glass of water, pure as water can be, is better understood as containing H2O, OH–, H3O+ and other related but less common ions, and even this is a vast oversimplification (if we could get truly pure water, which we cannot). Our current best understanding of the electron transfers that give water the properties we observe is a statistical average of ever changing interactions so complex as to be quite literally unthinkable. Indeed, the problem is “not that we are unsure which (distribution of types of) microstructure is the correct one. The point is that there is no one correct microstructure, because the microstructure depends as much on the context and functions just as another nominal essence would” (van Brakel, 2000b, 80–81).

This is why chemists use the ‘mixture of ions’ model to describe water’s macroscopic behavior. The only thing we can say about a glass of water that is not, strictly speaking, an error is that the average ratio of atoms in the glass is 2 H: 1 O and that it has the macroscopic properties of water. If there are other kinds of atoms in the glass, or if the ratio is other than , then we do not have pure water. If the ratio is but it does not have the macroscopic properties (pH, boiling point, etc.) of water then we have not water but a mixture of hydrogen and oxygen molecules in their elemental form. Chemical analysis and experiment deals with water not as an individuated molecule but in macroscopic quantities. All the typical observable properties of water—its pH, its density, its boiling and freezing points, its utility as a solvent, are dependent not upon its atomic ratio but the interactions between the dissociated ions. Philosophers of chemistry have been arguing this point for at least 25 years....

The idea that water simply is H2O is one of those false reductions that people can't seem to get out of their heads. What is actually true is that if you break apart the bonds in water you'll get a ratio of hydrogen to oxygen that's roughly 2:1; a very large amount of this will be from H2O, some from OH, some from H3O, etc., and it is the overall interaction of all of these, not just properties peculiar to H2O, that give us what we call water, because the properties of water arise not from the molecule but from constant, widespread dissolutions and reformations of H2O and related molecules. The matter is complicated by the fact that not even all H2O is the same; most involves the protium isotope of hydrogen (one proton), a small number have deuterium (when you have water in which a very high percentage of the hydrogen is deuterium you have heavy water, which is used in nuclear reactors -- heavy water is water, but it's poisonous in large quantities), and a small number involve tritium (which in large quantities would give you tritiated or super-heavy water, which is corrosive and, if I am not misremembering, radioactive). And that's not even counting the fact that the oxygen can occur in isotopes 17, 18, and 19, each one resulting in molecules that behave differently. Water is an interacting society, not a molecule, and it is a society of related molecules, not just H2O; among those molecules H2O is just the most prominent family, not a single kind of molecule; and light water (what we usually think of as H2O) is just the most prominent branch of that family. What looked like a simple fact is in fact not simple at all.

ADDED LATER (September 2018): Since this continues to be a fairly popular page, a few updates are perhaps in order. The following is a good summary discussion from a chemist's perspective of the (many, many) complexities that are involved in understanding water:

Martin Chaplin, Water Molecule Structure

Michael Wesiberg's paper is also available at Academia.edu. It's still worth reading.

If you have JSTOR access through a library, you can read van Brakel's paper there. VandeWall's paper is also available there.

B. C. Malt has an older paper, "Water Is Not H2O" [Cognitive Psychology 27:41--70 (1994)], that is written from the perspective of cognitive science, and does a good job arguing that people in ordinary everyday life also don't necessarily think of 'water' as designating a single kind of thing (e.g., there is a functional component). This is relevant because I think one reason why the water-is-H2O reduction won't die is that philosophers radically underestimate how complicated the requirements for good classification are when it comes to water -- and this is true for ordinary language as well as for chemists. You can read the abstract for Malt's paper here.


  1. Arsen Darnay11:51 AM

    Great post, was unaware of this, but right up my alley. I like that image of yours, "an interacting society." A recurring thought of mine these days is, for a materialistic society, we're not materialistic enough...

  2. Bryce1:06 PM

    I don't know that we should say water isn't H20, since it still remains the case that a given glass of water is constituted by, among other things, H20. Perhaps it's just more accurate to say "water is more than H20?" For the fact that a thing is more than one type of thing doesn't mean it isn't still that one type.

  3. Chris1:28 PM

    A psychologist said that water is not H20 17 years ago:

    Malt, B.C. (1994). Water is not H2O. Cognitive Psychology, 27, 41-70.

    Just sayin'.

  4. Brigitte1:30 PM

    I had never before heard the name J. van Brakel.<span>  </span>My revered Chemistry Professor in the Highschool I attended in Germany did not invoke his name. <span> </span>But I have not forgotten Herr Professor’s insistence on Chemistry as NOT the science of substances (Es ist nicht die Wissenschaft der Stoffe; es ist die Wissenschaft des Stoffwechsels).
    Now here you bring me news about someone who in the 17<sup>th</sup> century already had discovered this truth.<span>  </span>Though late in life, I am delighted <span> </span>to have this so clearly illustrated in your post.
    I know only one other blogger whose daily posts delight and teach me as much.<span></span>

  5. branemrys3:39 PM

    I think I remember you mentioning that when last I said something about the topic; it was a good paper, if I recall it correctly. Sometimes it does pay to listen to psychologists!

  6. branemrys3:51 PM

    Colloquially, yes, I think you're right.

    But when we speak more strictly (as when it is used as a philosophical example) H2O is just a molecule, whereas water is a substance with certain physical properties (many of which H2O doesn't have). And it's arguablly not even strictly a ncessary condition: any substance that had broadly the same macrophysical properties of water and on analysis could be broken down into approximately 2 parts hydrogen atoms to one part oxygen atoms, would chemically be water, regardless of whether it had any H2O in it or not. The importance of H2O is largely just a statistical phenomenon about water; it's just it'd be vanishingly unlikely to find anything meeting both criteria that didn't have a hefty quantity of H2O; many of the macrophysical properties characteristic of ordinary water are due to the composition and decomposition of OH and H3O to and from H2O.

  7. branemrys3:55 PM

    High praise!

    'Stoffwechsel' is one of those very interesting German words that packs a lot into short space.

  8. love the girls10:34 PM

    <span>Water is not H2O. True.

    Nor is it a complexity as explained in the article, because if it was, then substance is nothing more than a complexity of accidents. And bread is what we consume thinking it is Christ because the complexity of accidents are the substance. 

    What water is, is water. What water has are characteristics that God in his wisdom made knowable to us. Characteristics knowable to us in a simplistic manner so that we could manipulate matter for the manufacture of goods for our use.

    Characteristics are not substance.</span>

  9. branemrys9:17 AM

    In fact, this does not follow; any more than it follows that because a rock is a substance it is not a composition of parts. Saying otherwise confuses part-whole relations with an accident-substance relation; they are not at all the same.

  10. I am of course being a bit silly. Water is not WATER (putting words in all caps is the convention in psychology when referring to concepts). WATER is, like most (if not all) concepts, polysemous. WATER as we generally use it, to refer to what's in our glass, or in a lake, etc., is not H20, because that's not how we use it (Malt shows in essence that our use of WATER is not correlated with H20, or at least not with the proportion of H20 in the substance we're referring to). It's up to chemists and philosophers to figure out whether WATER used in the technical sense is H20, as they are doing in the literature you talk about here, along with those debating externalism and internalism (which debates findings like Malt's can contribute to, of course). But I do think it's funny that a philosophy of chemistry paper has the same title as an old cog psy paper.

  11. branemrys10:44 AM

    Right; I see papers like Malt's as problematizing things from the other direction -- that even in popular speech, and despite the cliche, the link between the two is loose. Weisberg's paper notes a phenomenon that's fairly similar even in more technical contexts, in that chemists also don't correlate WATER with the proportion of H2O; perhaps because chemists, like ordinary people, have reasons for counting and discounting things as water for particular everyday purposes (whether it's ordinary everyday purposes or routine work in a chem lab). In other words, while it doesn't directly deal with technical contexts, it's the sort of work that should at least have had people looking for the specific mechanisms by which similar kinds of looseness are avoided in technical contexts, to see what they imply.

  12. love the girls11:56 AM

    I did not say composition of parts.  I specifically said complexity of accidents because that is what water would be according to your article.  There would not be a substance except perhaps an underlying one which would not be water but that which somewhere along the line underlys water.

    The principle is a rather simple one, God made a world each and evey man could know given the senses we have at our disposal.   Your explanation says water is not water as we understand water to exist, but is instead a hidden complexity which has the appearance of water which can only actually be known by modern technical devise.

    What it comes down to is how do we approach the subject at hand.  You say water isn't molecules but is instead a complexity of molecules.  Where as I say no, molecules don't actually exist, but that God created water so that it could be understood as having the characteristic of molecules as model so that we could manipulate it.

  13. branemrys2:50 PM

    But I don't talk about accidents in the post; I talk about parts.

  14. love the girls2:26 PM

    The point is, while some empirical evidence may not be explainable, nevertheless the explanation that is given cannot deny any of the empirical evidence.  

    The molecular theory you posit as existing does deny what the senses tell us does exist.  And there is nothing unusual about it, for instance that same system of knowledge likewise tells us that the colours exist in our imagination and not in the object percieved.

    Where as a correct explanation would likewise account for the leaves actually being green, just as we see them as green.  Our direct experience is also knowledge, and it must be accounted for as we perceive it.

    Your explanation of water is void with small bits of energy stuff spread far apart.  That is not how we percieve water when we take a bath in the stuff. 

  15. branemrys11:53 PM

    The molecular theory you posit as existing does deny what the senses tell us does exist.

    It does not. You keep saying this; but you have yet to give any argument for it.

    Look, if you deny the existence of molecular parts, there are only two possibilities: either you are claiming that water is indivisible, or you are claiming that water is infinitely divisible into every smaller watery parts. If it is only finitely divisible, then it divides into some kind of molecular parts, and all that is to be determined is the scale at which division stops yielding something identifiable in some way as water. It is sheer nonsense to pretend that either the indivisibility of water or the infinite divisibility of water are required by our sensory experience of water; the former is contradicted outright by it, and the latter is a claim far exceeding anything the senses could prove even in principle.

    Likewise, it is nonsense to claim that the molecular account makes water a "void with small bits of energy stuff spread far apart"; this betrays a complete misunderstanding of what is involved in molecular interactions, not to mention a complete inability to understand scale: molecules in a bath would not be 'spread far apart' by any rational measure of 'far apart'.

  16. love the girls3:58 AM

    You have the burden of proof backwards.  It is not my duty to explain what water is by nature.

    Secondly, eventually you will end up with some entity which I am claiming water to be, because those molecules are likewise made out of something that somewhere along the line will not be something else than itself.  

    Further, the atomic theory posits large voids in relation to the size of the atoms themselves so that what for the most part exists is void but I won't push this aspect of the argument.

    So back to my prior point :

    What we apprehend is substances.

    Where as your molecules differentiate human flesh from bread by accidental arrangements.  Size, place, and so forth.  As I wrote before, once you posit molecules there may be a underlying substance somewhere, but bread and flesh are not that underlying substance, and thus the accidents are the substance according to what we perceive substances to be.  Because while we perceive substantial difference, what there actually is is accidental difference.  

    But we don't apprehend bread and human flesh as accidentally different, but substantially different.   Which is the problem.  

    It's not my burden to explain the nature of bread and human flesh, but the burden of those who take it on by giving explanations such as molecules are what bread really is.  A burden which likewise requires the explanation account for our apprehension of bread being substantially different from human flesh.

    To a Catholic this matter greatly because our Faith specifically states Christ is in the Eucharist according to his substance and not according to his accidents.  The Faith is grounded in what we do perceive by our senses, seeing bread as substantially different from human flesh and in turn substantially different from water and substantially different from wine.

  17. branemrys8:32 AM

    (1) There is no burden of proof here in either direction. All that has happened is that you've shown up commenting on a post on a specific subject and made a lot of vague claims that you haven't backed up about a subject that is only loosely related to the original topic; pretending that this somehow imposes a burden of proof on other people is sheer nonsense.

    (2) Again, your talk of "large voids" completely neglects scale. I can't help it if you really have difficulty grasping the fact that everything on the molecular scale is really, really small, but stop talking about it as if we were talking about the interstellar medium.

    (3) Again, you just pull things out of the air. Molecules are not differentiated by purely accidental characteristics; they are different as substantial part is different from substantial part. They are no more, and no less, differentiated from other things by their accidental characteristics than water itself, or any part of water, is, and for precisely the same reasons

    (4) You are simply incorrect, in any case, about substances and accidents. We know accidents sensibly; we only know substances by way of accidents we sensibly perceive. I can show you references to this point in St. Thomas, if you'd like, and you can argue it out with him.With regard to the Eucharist the difference is accepted on the basis of divine testimony, and thus entirely indirect sensible evidence; again, I refer you to St. Thomas.

    (5) You still have not addressed the problem I raised before. There are only three alternatives here: either substances are indivisible, or they are infinitely divisible, or they are divisible but only finitely so. The first option is contradicted by our actual experience, the second option cannot be established on the evidence you keep appealing to, and the third option is a molecular thesis.

    In short: you are muddled on the issue, you ignore the arguments I provide, you make up things about my position that you do not and apparently cannot justify attributing to it, and you likewise make up nonsensical claims about burden of proof in order to get out of having to give any arguments of your own.

  18. Phoenix_from_the_flames8:01 PM


    so you deny that things have essences? Or you believe that essentialism can be salvaged even if water is not H2O?

  19. branemrys12:30 AM

    I don't see why essentialism in general depends on water having one particular composition.

    Part of the problem, perhaps, is the conflation of 'Water is H2O' taken essentialistically and 'Water is H2O' taken compositionally; the two are very different and can only really be linked if certain assumptions are established as true. The primary chemical reasons for saying 'Water is H2O' in the first place were always compositional; the common essentialist reading of the compositional claim seems to me to be due more to crude reductionism than to any sort of essentialism; or, perhaps, to taking essentialist requirements to be answered entirely by crude reductionism (so that identifying the essence of something is conflated with dentifying its parts at a molecular level).

  20. Phoenix_from_the_flames10:47 AM

    Ok. But, at this point, i'm wondering what the correct definition of water really is: would something like "a liquid (proximate genus) whose chemical constituents have a ratio of 2:1 (specific difference)" be correct?

  21. Phoenix_from_the_flames2:15 PM

    *Oops. Of course i meant "a liquid composed of hydrogen and oxygen in a ratio of 2:1".

  22. branemrys5:04 PM

    That's a good question. I don't know the answer. We're talking real rather than nominal definitions here, and real definitions are very hard to pin down precisely. Broadly speaking, there are two kinds of approaches one can take: either a genus/differentia approach, or the more indirect a total-cause approach. The former really needs to be determined by activity rather than composition -- the essence is that which gives a thing the nature it has, i.e., its character as a principle of action. Genus/Difference definitions are really trying to pin down this characteristic act directly, and composition is not particularly helpful for that. So for instance, calling human beings 'rational animals' identifies us as the animals that have the capacity for rational acts -- even if we don't actually exercise them, that's the act-type that makes explicit our distinctiveness from other animals and, likewise, even if other animals were to occasionally under unusual circumstances to engage in these acts (Balaam's ass, perhaps), it wouldn't matter because the acts are not as natural to them as they are to us. Such is the idea, anyway. So a genus/difference definition would require identifying what it is that water most distinctively and naturally does.  (I don't think liquid could be the genus, because we'd want to take phases into accounts, just as in characterizing animals we want to take sexual differentiations into account.) What are usually the tell-tale features of water that most commonly mark it out from similar substances? That's where we'd start to rough at answer.

    The 2:1 ratio would make sense as a material cause component of the latter approach to the definition. It's possible it might come in with the genus/difference approach, too, though; if you asked a chemist what the genus of water was, and could make him understand what you meant by 'genus' in this context, I suspect he might say something like "Water is a chemical substance" or "Water is a simple substance" -- chemical substances being substances that have the property of constant composition -- which is marked out by what you can consistently decompose them into. So if that route were taken, we'd be getting close to your suggestion, although I don't think we'd have completely captured the most proximate genus, and we'd still have questions about how exactly to characterize the specific difference.

  23. Phoenix_from_the_flames5:36 PM

    That's very helpful. Thanks!

  24. Alexander Pruss1:13 PM

    Granted, a single molecule of H2O is not water.  But it does not follow that H2O is not water.  After all, it might also be that a single molecule of H2O is also not H2O.

    I think that when we use a chemical name like "H2O" or "sodium chloride", we may mean something like: "The substance (in the chemical, not necessarily philosophical, sense) whose molecules have such-and-such a chemical structure."

    Granted, one might look at a drawing of a molecule of H2O and say "That's H2O."  But that might just be synecdoche.

  25. branemrys4:52 PM

    I think if we are going to claim that a single molecule of H2O is not H2O that we have arguably begun stipulating the meaning of the terms to such an extent that it we end up clearly jettisoning the reduction anyway -- your suggestion just ends up being a suggestion that we should treat the name 'H2O' as a synonym for 'water', which we certainly can do (and obviously often do in colloquial contexts), but this simply makes "Water is H2O" a tautology by stipulation, rather than a substantive statement. We could do the same thing with, say, "The mind is the brain" by insisting that by 'the brain' we often mean just 'our thinking part, which has bodily effects by activation of neurons'.  This is actually pretty close to our colloquial use of the word 'brain', but it's pretty clear that if we are using the term in this way, "The mind is the brain" is no longer a reductionistic statement, but simply one whose terms have been deliberately adjusted into synonymy, whether strict synonymy or synonymy for most practical purposes. So here.

    In any case, when chemists use the chemical name H2O they seem clearly to include single molecules of H2O, because that's the point of the name. Or to put it in other words, both the pedagogical and experimental practice seem to me to imply that your suggestion is entirely upside down: it is when we use H2O as a mass noun that we are engaging in synecdoche -- everything suggests that the synecdoche is in a pars pro toto direction, not a totum pro parte direction. I think even your formulation suggests this: what is the "such-and-such chemical structure" that is relevant for this substance? Why, it's what we usually designate as H2O. Where do we get this name 'H2O'? In clear contrast to where we get the name 'water', it's from scientific thinking about the structure of individual molecules.

  26. granfred3:10 AM

    I agree.
    Water is just like mercury; an element.
    It is an icosahedron.
    Platonic solid.

  27. Lynn Eykamp6:42 PM

    At magneticwaterscience we take it even further that Water is not H20 as H and O do not exist. The production of 2 gases by electrolysis is that one is a very negatively charged water vapor and the other is a very positively charged water vapor.

    With this Newer concept of the atomic structure where everything is Water, We have for over 20 years built many prototypes and working devices that do the following. By just passing any liquid through a magnetic field and in some devices just passing any liquid through a ring magnet said liquid be it, acid mine waster, raw sewerage, sea water or fresh liquid concrete it exits out the other end of the ring magnet as fresh water. If the magnetic field is reversed then fresh water entering the magnetic fields or a ring magnet exits the field or ring magnet as "saudi like" crude oil. There are pictures and even videos of this process at magneticwaterscience. We understand the natural magnetic fields of the earth and its 'electro-magnetically' restructuring of underground water into oil and duplicate this process. Only a fossil head would think otherwise that such tonnage of coal and oil buried miles underground would be anything other than Abiotic in origin.

  28. Lynn Eykamp6:47 PM

    There are no elements. Everything is a Magnetic Resonant Field Pattern of Water. You have been duped by Morgan and Westinghouse's promotion of Dumbeinstiens particle theories so as to give you a meter.

    At magneticwaterscience you can learn the true nature of the Atomic Structure that its an energy field, just like Tesla said, Everything is energy, frequency and vibration' he purposely left out particles and publicly debated Einstein about his "silly equations".


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