Too much vacuum in his head

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That's what Descartes said to Huygens about Pascal. Another Shoebox cartoon, this one by brian, gives the background:

There's some serious history behind this famous but widely misunderstood slogan, coined originally (I think) by Hero of Alexandria. Before Pascal and Descartes (and Boyle and Hobbes and a cast of thousands), there was Hero's footnote to Aristotle's "plenism".

For the background, we turn to the Stanford Encyclopedia of Philosophy's article on Nothingness:

Aristotle denied the void can explain why things move. Movement requires a mover that is pushing or pulling the object. An object in a vacuum is not in contact with anything else. If the object did move, there would be nothing to impede its motion. Therefore, any motion in a vacuum would be at an unlimited speed.

Aristotle's refutation of the void persuaded most commentators for the next 1500 years. There were two limited dissenters to his thesis that vacuums are impossible. The Stoics agreed that terrestrial vacuums are impossible but believed there must be a void surrounding the cosmos. Hero of Alexandria agreed that there are no naturally occurring vacuums but believed that they can be formed artificially. He cites pumps and siphons as evidence that voids can be created. Hero believed that bodies have a natural horror of vacuums and struggle to prevent their formation. You can feel the antipathy by trying to open a bellows that has had its air hole plugged. Try as you might, you cannot separate the sides. However, unlike Aristotle, Hero thought that if you and the bellows were tremendously strong, you could separate the sides and create a vacuum.

Hero's views became more discussed after the Church's anti-Aristotelian condemnation of 1277 which required Christian scholars to allow for the possibility of a vacuum. […]

… scholars writing in the aftermath of the condemnation of 1277 proposed various recipes for creating vacuums. One scheme was to freeze a sphere filled with water. After the water contracted into ice, a vacuum would form at the top.

Aristotelians replied that the sphere would bend at its weakest point. When the vacuists stipulated that the sphere was perfect, the rejoinder was that this would simply prevent the water from turning into ice.

Neither side appears to have tried out the recipe. If either had, then they would have discovered that freezing water expands rather than contracts. […]

Hero was eventually refuted by experiments with barometers conducted by Evangelista Torricelli and Blaise Pascal. Their barometer consisted of a tube partially submerged, upside down in a bowl of mercury. What keeps the mercury suspended in the tube? Is there an unnatural vacuum that causes the surrounding glass to pull the liquid up? Or is there no vacuum at all but rather some rarefied and invisible matter in the “empty space”? Pascal answered that there really was nothing holding up the mercury. The mercury rises and falls due to variations in the weight of the atmosphere. The mercury is being pushed up the tube, not pulled up by anything.

When Pascal offered this explanation to the plenist Descartes, Descartes wrote Christian Huygens that Pascal had too much vacuum in his head. Descartes identified bodies with extension and so had no room for vacuums.

Descartes was not the only 17th-century wit to make this joke. Thus Thomas Pecke, "Upon Marcus", 1659:

Why durst you offer Marcus to aver
Nature abhorr'd a vacuum ? confer
But with your empty skull, then you'll agree
Nature will suffer a vacuitie.

There's a more extended and more effective version of the joke in Roger Boyle, Earl of Orrery, Mr Anthony, A Comedy (which seems to have been a sort of 17th-century Breakfast Club), where Mr. Anthony and his friend Jack Plot gang up on Mr. Pedagog:

Plot: How like you this, Mr. Pedagog , have I not taught your Pupil rarely this Morning?

Anthony:  Prethee let me have my full swinge at him (for he has had his many a dismal time at me:) I say, if thou dost not conform to all the Maxims of Jack Plot, Tom Art , and my own dear self, I will peach thee at such a rate to my Sire, as shall provoke him to uncase thee out of thy Pedagogical Cassock, Condemn to the Flame, Martyrlike all thy Ferula's, Grammars, Dictionaries, Classick Authors, and Common-Place Books; nay, take thy Green Glasses out of thy Spectacles, and leave thee only thy Horn-cases to look through; by which, thou wilt be as able to read Prayers with thy Nose as with thy Eyes.

Plot: Nay, if thou dost not frisk as lustily to a single Kit, whenever thy late Pupil and my present Convert bids thee, as to 24 Violins, I will Convert thy Lictorian Bundles of Birch, which Consul-like thou hast carryed before thee, into Rods for thy own Posteriors, and have no more mercy on thy Hanches, than thou usest to have on my Friend Anthony 's, when he cannot say his Lesson, though he be the greatest Dunce of the two; only his Imbecillity, varnish'd over with a Pythagorean Gravity, passes for profound Knowledge in thy Fathers Shallow Pate; where, if there is a Vacuum in Nature, there it needs must be.

Anthony: By this hand, I long to open it, to try the Experiment.

It's not clear to me whether (or how) Mr. Anthony's author, Roger Boyle,  was related to Robert Boyle, the antagonist of Thomas Hobbes in an important controversy about the existence of vacuums and the proper conduct of scientific investigation. Anyhow, Hobbes hated Descartes, but agreed with him about vacuums.

See Shapin and Schaffer, Leviathan and the Air-Pump, 1985; but also see Noel Malcolm, Aspects of Hobbes (2002), pp. 190-196:

By the time he published De corpora in 1655, Hobbes had actually adopted … a plenist theory, denying the existence of any empty spaces — even at the atomic level — in the universe. Why did he make this change? According to Shapin and Schaffer, the fundamental reasons were political. Hobbes settled on a materialist plenism in order to exclude 'incorporeal substances', such as spirits and the human soul …, because these were the props and devices used by priestcraft to harness people's fears and thereby gain power in the state, subverting lawful authority. The difficulty with this explanation is that his attack on 'incorporeal substance' required only materialism; it did not require plenism too. […]

The real reasons for Hobbes' shift from vacuist to plenist are to be found in experimental physics […] 'It is said that one can see through the empty space […] from which it follows that the action of a light-producing body is being propagated through a vacuum (which I think is impossible).'

Though action at a distance remains unmediated by ethereal vortices, the story continues, and not just in the comics:

Historians of science wonder whether the ether that was loudly pushed out the front door of physics is quietly returning through the back door under the guise of “space”. Quantum field theory provides especially fertile area for such speculation. Particles are created with the help of energy present in “vacuums”. To say that vacuums have energy and energy is convertible into mass, is to deny that vacuums are empty. Many physicists revel in the discovery that vacuums are far from empty.

[Update — I'm very sorry to say that the remark attributed to Descartes may be a myth, or perhaps an exaggeration (In the Stanford Encyclopedia, too, and many other apparently authoritative places!) At least, according to Daniel Garber, Descartes' Metaphysical Physics, p. 142:

All Descartes ever got from Pascal was the promise of a refutation of his preferred explanation. At the end of the Expériences nouvelles, a preliminary outline of a never completed treatise on the vacuum, Pascal promised to respond to the objection "that a matter imperceptible, extraordinary, and unknown to all of the senses fills the space [above the column]," a position formulated with Descartes in mind, no doubt. Descartes seems to have received the work in good humor. Writing to Huygens on 8 December [1647], shortly after having received the Expériences nouvelles, he noted:

It appears to me that the young man who wrote this booklet has the vacuum a bit too much on his mind, and is somewhat hasty. I wish the volume he promises were already available, so that one could see his reasons, which are, if I am not mistaken, insufficiently solid for what he has undertaken to prove. (AT V 653)

It's not at all clear from this translation that D was really making a joke about P having "too much vacuum in his head" — it would be nice to see the original French (or Latin?).]


  1. Lugubert said,

    August 9, 2009 @ 7:46 am

    Another way of reacting to vacuum:

  2. MattF said,

    August 9, 2009 @ 8:50 am

    Note that in the modern world of today, the vacuum is not inert and will interact with light and matter, if pushed hard enough.

  3. James said,

    August 9, 2009 @ 9:04 am

    Gary Larson was waaaay out in front of the Shoebox:

  4. John Cowan said,

    August 9, 2009 @ 1:45 pm

    Robert and Roger were brothers, the 11th and 14th children of Richard Boyle, 1st Earl of Cork, according to Wikipedia.

    I realize that you're just quoting the SPE here, but I don't see how it can say that Torricelli's 1643 experiment refuted Hero's views. On the contrary, it confirmed them: the space in the tube above the mercury really is a vacuum, and is called a Torricellian vacuum to this day. There's some mercury vapor in the vacuum, but if you remove and seal the tube and freeze it (mercury freezes at about -38 degrees, C or F as you prefer), you will remove that as well. A superior vacuum was not achieved until the middle of the 19th century.

    [(myl) Here's what I think the argument is. Hero's theory (at least as interpreted in the 17th century) says that what causes the mercury in the barometer to rise in the tube (above the level of the surrounding mercury open to the air) is an active attempt by the fluid mercury to prevent a vacuum from existing; whereas Pascal (for example) argued that it was the pressure of the atmosphere on the mercury open to the air that pushed it up. If you read Pascal and others on the topic, they certainly thought that their experiments (e.g. Pascal's barometer-within-a-barometer) were a refutation of Hero's idea.

    (See e.g. Henning Genz, Nothingness, pp. 94-128 (or search for "horror vacui")]

  5. Emily said,

    August 9, 2009 @ 2:56 pm

    It's not only nature that abhors a vacuum– for some people, so does art:

  6. D.O. said,

    August 9, 2009 @ 3:20 pm

    Can somebody explain me why it is "a vacuum"? Is there any logic behind it? Not that vacuum is a countable noun. If it just another quirk of English language, any reason there is this particular quirk?

  7. Janice Huth Byer said,

    August 9, 2009 @ 4:29 pm

    Ah. The phrase being ancient explains why it always seemed at odds, well, to me, with my feeble grasp of physics, with that other obviously "younger" phrase that has nature rushing in to fill a vacuum. To me, that suggested nature doesn't abhor a vacuum – it adores it. Or, am I just a hopeless romantic.

  8. D.O. said,

    August 9, 2009 @ 4:47 pm

    Sorry for irrelevant question above. Vacuum can be a countable noun as it happens. Sorry again.

  9. Emily said,

    August 9, 2009 @ 5:21 pm

    By the way, I have also understood "nature abhors a vacuum" to mean that living organisms will colonize any available niche, though I can't recall where I've seen it used in that sense. But this personal interpretation fits with the understanding of "nature" to mean "life on Earth, untouched by humans" instead of "the laws of physics or the physical world", which is also the interpretation seen in the Shoebox and Far Side cartoons.

  10. dr pepper said,

    August 9, 2009 @ 11:48 pm

    I read a story once that included a gunfight in a structure on the Moon. One shot pierces an outer wall. Then there is a lot of description of air hissing and things flying through the hole. The author ends the paragraph with the phrase "the dome was breached, and nature abhorred the absence of a vacuum".

  11. Ginger Yellow said,

    August 10, 2009 @ 5:17 am

    "Neither side appears to have tried out the recipe. If either had, then they would have discovered that freezing water expands rather than contracts"

    This sort of thing always stuns me when I'm reading about proto-science. The Greeks and their Islamic acolytes discovered amazing things with astoundingly primitive equipment – the diameter of the earth being a famous example – yet the most basic empirical facts eluded them/us for thousands of years. It's understandable, I suppose – it wasn't all that easy to freeze things on demand in those days – but, still. You'd have thought someone would have left a mug of water out overnight in winter or something like that.

  12. Cameron said,

    August 10, 2009 @ 10:49 am

    One of the slogans cited in the 17th century documents usually called the "Rosicrucian manifestos" is "nequamquam vacuum".

    Other than pointing out what side of the debate the purported Rosicrucians were on, all that fact adds is the lovely sound of that Latin emphatic negative, "nequamquam . . ."

    [(myl) Lewis & Short has nequaquam; and Perseus turns up Lucretius De Rerum Natura I.505-507

    nam qua cumque vacat spatium, quod inane vocamus,
    corpus ea non est; qua porro cumque tenet se
    corpus, ea vacuum nequaquam constat inane.

    wherever there's space that we call a void,
    there is no body; and so where there is
    body, there is not at all an empty void

    (Translation provided with no warranty of fitness for any purpose…)]

  13. J. W. Brewer said,

    August 10, 2009 @ 2:59 pm

    @Ginger: Presumably the Greeks et al. had at least observed that ice floats rather than sinks when placed in water. From this the conclusion that water expands when it freezes seems intuitively obvious, by which I mean I must have learned some simple principle in elementary school or junior high school which I no longer recall not knowing but which was totally unknown to the ancients. The original Eureka anecdote indicates that they eventually figured out density as weight/volume, and you'd think they could have figured out (by e.g. noting that olive oil floated on water rather than vice versa and figuring out which weighed more per amphora-full) that stuff that floats is less dense than what it floats on. Maybe they needed the notion that mass is conserved during the change of state from liquid to solid?

    [(my) I suspect (without any evidence) that in classical Greece, and for that matter in 13th-C Europe, there were plenty of people who knew that water expands when it freezes; but the philosophers (at Paris, Bologna, and Oxford?) who debated the theory of the vacuum after 1277 were apparently not among them. And of course, there's always the question of whether the story in the SEP entry is true — I'm already doubtful about the Descartes-dissed-Pascal tale, so maybe this one is embellished as well.]

  14. Ginger Yellow said,

    August 11, 2009 @ 5:57 am

    That's entirely possible. For what it's worth, here's some info on the knowledge of Archimedes' work in the Middle Ages, from a review of an English translation:

    Yet it seems as if no one in the Byzantine Empire
    read them. Archimedes’ name continues to
    crop up in Byzantine literature, but he is the
    Archimedes of the old anecdotes, not the mathematical
    writer. No further copies of the Archimedes
    codices were made. In fact, by about A.D. 1300 all
    three codices were in situations where Byzantine
    scholars could no longer read them. Two of them
    had somehow made their way to western Europe,
    where Greek learning was still rather scarce. Perhaps
    they were part of a royal gift, like the manuscript
    of Ptolemy’s Almagest that the Byzantine
    emperor Manuel Comnenus gave to the Norman
    king William I of Sicily about 1160. Whatever the
    story, by 1300 these manuscripts had become part
    of the small collection of Greek manuscripts in
    the papal library (one of them was in pretty bad condition).
    After the papacy was moved to Avignon in
    1309, the papal manuscripts seem to have been
    dispersed, and only one of the Archimedes manuscripts
    eventually resurfaced in the fifteenth
    century. Greek humanism was now in full flower
    in Italy, and good copies were made of this survivor
    before it again vanished, this time for good. Apparently
    the other manuscript had never been
    copied, though a painstaking Latin translation of
    the contents of both manuscripts had been made
    by the Dominican scholar William of Moerbeke in
    1269, and this Latin version has survived.

  15. Icons & Curiosities — A First Things Blog said,

    August 11, 2009 @ 8:03 am

    […] A cartoon, via the Language Log: […]

  16. D. Des Chene said,

    November 8, 2012 @ 12:36 am

    The French is (with updated orthography):

    Il me semble que le jeune homme qui a fait ce livret a le vide un peu trop en sa teste, et qu’il se hâte beaucoup. Je voudrais que le volume qu’il promet fût déjà au jour, afin qu’on pût voir ses raisons, qui seront, si je ne me trompe, aussi peu solides que ce qu’il a entrepris de prouver (AT 5:653, Descartes to Huygens 8 Dec 1647)

    The supposed joke is indeed a myth.

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