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Haldane's Theorems, Graunt on the Bubonic Plague, Science of Conjecture, Darwin, Gould, Pepys on the Plague, Browne, Butler, Fewmets, Elephant on the Moon, Eco-battiness, Global Warming, The Forgotten Man, Cooperative Commonwealth, Economist and Cats, Pedantry, Evolution, Directory
Analysis of the Way in Which the Plague Was Spread -
Much has been written of the plague (as example, mentioned in a book by Al Gore), it was a common visitor to all countries and was attributed to a variety of causes, none of which were provable until the advent of scientific discovery. This was made abundantly clear by Ian Hacking in his book, The Emergence of Probability, published by Cambridge University Press in 1975.
Before the germ theory became established, miasma (bad or evil air) was thought to be the cause of disease, or perhaps the signs were right for its occurrence. Signs included everything from the placement of the stars, conjunction of the planets, animals gone mad or acting strangely, and of course witchcraft. Cohabitation of vermin and man took place then as well as now, and to rule out the role of rodents and their fleas without firm evidence was unjustified. Living with fleas, body lice and other insects was not only unavoidable, but changing seasons were the only control over their increase and spread.
In this environment, Ian Hacking set out to document the way in which knowledge based on discovery came to replace that based on logic and the teaching of elders (Which Hacking likes to refer to as epistemological.) In the case of the plague, proof that the flea was somehow involved in transmission of the disease was impossible since fleas were common travelers in life and being bitten by a flea more likely than not did not cause any ill effects other than the initial discomfort. Their crawling/hopping about and occasional biting was just a part of life.
If the proposition that the plague is transmitted by fleas were proposed during those times were raised, imagine how it would be refuted. "I've got fleas and I don't have the plague" would have been an easy rejoinder". It was not possible to know until at the very least, we possess enough epidemiology to distinguish bubonic from pneumonic plague, and enough parasitology to distinguish the relevant kinds of fleas and perhaps their host. Bubonic plague (as characterized by the eruption of buboes) is transmitted by a flea, and pneumonic is not. But dead is dead! When we have an understanding of pestilence, then we may begin to frame definitions that characterize the concepts in the scientifically relevant way, and then an understanding of man's reaction to the two different means of transmittal becomes important.
Once we have an adequate theory of causative agents for the plague it is at least plausible to say that by definition a particular kind of bubonic plague is transmitted by a particular member of the Siphonaptera. (flea family) That's a start
Hacking cited three examples of the evolution of thought on the causes of the plague:
1) A resident of Cairo in 1837 who conjectures that the plague infesting his city was transmitted by fleas.
2) A neighbor attributing the plague to miasma (the unwholesome environment created by man - sound familiar(?)).
3) The Londoners of 1603 who blamed imported cotton for their plague (Hacking writes that there is a particular parasite (Yersinia pestis) that needs a flea, that needs cotton (I do not know from whence this bit of information comes - the bacteria is quite capable of living and reproducing free from a flea host, and fleas are blood suckers and while they perhaps can live on cotton, it would not be the best "growth" media.. jsw)
The propositions about the plague now accepted in epidemiology simply did not exist a century or more ago, and certainly not in the mid 1600's. Bubonic and pneumonic plagues had not, for example, been distinguished, and the very concept of a host parasite was undreamt of. There is a certain family resemblance between present knowledge and old opinions, but arguably no proposition central to modern theories of the plague is identical to any proposition believed centuries ago. Perhaps, the world was different then - reconstructing the events is a messy task (See note following)
Herein lies the best of Hacking's work. He says that, "OPINION IS THE COMPANION OF PROBABILITY WITHIN THE MEDIEVAL EPISTEMOLOGY(beforehand knowledge)." Which is to say, that one could take any of the three "causes" cited above and form an opinion of "probable cause" of the plague. Evaluating those opinions with the evidence at hand requires an understanding of the SIGNS.
Signs are not prognostications but are a characterization of the environment under which the disease is observed. True you may record the sign of the moon, but temperature and season of year, dwelling in close quarters rather than widely separated, with small children, good nutrition or not, etc., all can be the signs that lead to a probability of occurrence.
And then we have the symptoms themselves. As Braunsweig wrote, �When a man hath a great disease or feebleness and a cold sweat breaketh out only about the nose'. (Braunsweig called them �a very deadly sign' - Ah well, the terms do get used interchangeably, jsw) Which can lead to a finding of cause - "...
The domain of causation we will have a set of universal propositions involving primary qualities only. Knowledge of this is knowledge of how the world works; it is science. However. at the level of phenomena there is something else. When the patient comes to Fracastoro, he is blotched, stinks, complains of a foul taste in his mouth and sounds strange when thumped on the back; above all he complains of pain. The causes of all this lie inside the patient...
Even at the time of the Cairo plague of 1834-5 the question of miasmic versus infection theories of pestilence remained unsettled. Most people had always blended the two. Thus Danish Bishop Aarhus, in a work translated into English in 1480, said that the 'reek and smoke of such sores is venemous and corrupteth the air' and advised us to flee from sick people to avoid the miasma they caused. 'Fly far and return late' as Thomas Lodge summed it up in his 1603 Treatise of the Plague. We now find bizarre the theory of Kellwaye that flocks of children corrupt the air, especially at burials - a theory which led to banning poor children from attending the interment of richer folk, doubtless in fact for their own good. Equally useful was Lodge's warning that when 'rats, moles and other creatures (accustomed to live underground) forsake their holes and habitation, it is a token of corruption'. This doctrine, which goes back at least to Fracastoro's theory of probable signs, led to sound practice.
Petty (author of a book on analysis of the plague - Logic)or Graunt (Nature and Political Considerations) had the same beliefs about plague as a Kellwaye or a Lodge. Their miasmic theory on the origin of plague fit the facts fairly well. In due course it could explain the fact that plague often starts at the dock: foul air had been brought by ships from overseas. And the theory had practical consequences of which we still approve: Flee, avoid animals, and erect houses for quarantine. (Here one must take exception with Hacking as Graunt appeared open minded in his search for the relationships. Hacking should not have equated Graunt's "beliefs" with his theories.)
It is not on point of medical theory that we distinguish a Petty from a Kellwaye. It is in terms of how to assess the theory. For Lodge in 1603, swarms of mice are evidence of pestilence to come because such swarming is both sign and cause of corrupt air. Whether or not the evidence is evidence is part of the theory of corruption. Whether or not something is a sign is itself part of the theory. There is no independent epistemological criterion. (Which I suppose Hacking meant, that prior learning had given not a clue as to the cause and so there was no basis for judgement.) Only when epistemological criteria (Perhaps he meant that having established a basis for judgement, one can now begin to take each theory of the cause and subject it to number crunching and thus have a means for assessing the validity of that particular theory.(?))can be grasped independently of the causal theory can probability and the use of statistics emerge. Only then shall we find a Petty inviting us to conduct controlled experiments to discover 'whether of 100 sick of acute diseases who use physicians, as many die in misery as where no art is used, or only chance'. . The relationship between the data obtained by such an enquiry, and hypotheses about the efficacy of doctors, is not a causal one - it does not depend on any particular theory of medicine. It is an epistemological relationship independent of the particular subject matter. As soon as men have distinguished epistemological from causal concepts of evidence, we can begin reasoning with Graunt, (We cannot reason with John Graunt, he died some three hundred and fifty years ago. We can however, begin to appreciate his use of statistics to evaluate and seek confirmation of a theory.)"
The contagion of the plagues depends more upon the disposition of the air than upon the effiuvia from the bodies of men (This would have been more readily demonstrated by looking at death records of the "old women" who were called upon to remove the bodies. If their immediate contact with the dead had resulted in their deaths, it is unlikely that they and others could have been forced into service.) Which also we prove by the sudden jumpings which the plague hath made, leaping in one week from 118 to 927, and back again from 993 to 258, and from thence again the very next week to 852."
Only the weather varies so erratically, week by week. If the plague were passed from person to person we could not explain these statistics. (This is Hacking's analysis, not Graunt's.) The miasma versus infection controversy was centuries old. Here a new kind of data is for the first time brought to bear. As Sijssmilch said, Graunt was a Columbus"
And so we conclude with the help of Ian Hacking, that the Plague was finally characterized by the accumulation of knowledge (observation) and analysis of data to form an basis for judgement and understanding of the cause of the disease, and thus a means of treatment of the infection. In the note following, it is interesting that some still debate the affairs of state during the Plague epidemics.
Note:
The issue of the plague is further confused by studies of James W. Wood (Pennsylvania State University) who claims that the names "Black Death" and "bubonic plague" should not be associated with the disease that occurred in 1347- 1251 (presentation before the annual meeting of Physical Anthropologist in the spring of 2002)(a). Woods accepts the swelling of lymph glands to produce the "buboes" which ruptured as a sure sign of disease but feels that the agent for the disease cannot be readily identified and may have mutated from that which causes the current disease using the host, insect (flea) mammal (rodent), prior to spreading to man.
The two are at odds in reading the tea leaves of history. Woods claims there is no records of massive die-offs of rats prior to emergence of the disease. Whereas Hacking quotes from Braunsweig:
"�Often a tiny mouse shall give thee augury of ill.
No tie of love can hold it beneath the depths of the earth,
But it breaks forth from its trenches,
Forgets its life and its habits and
Leaves its tender young and abode...'
(From H. von Braunsweig in 1574)
The swarms of mice that occasionally overran some of the towns of Central Europe, thousands dying frothing in the streets, were indeed a probable sign of plague to come."
Further, Woods teaches that there was great loss of life and that this promoted the change from a rural society to less social stratification, whereas the statistics of John Graunt (1620-1674) tend to prove that while there was indeed great loss of life it was no where as great as others have written and that the population of London had recovered to an equal number of persons living there within two years.
Woods seems to believe that the spread of Black Death was "person-to-person" not using rats as a vector and there is no reason to believe that the bacillus could not be spread in such a manner. Hacking seems to believe that the bacillus was in the air and by changes in the weather brought on the increases in disease. However, Graunt's studies of the death list suggest that the Plague was bimodal, an early stage of the buboe-plague, followed in two years by the pneumonic-plague.
(a) C&EN, April 29, 2002, pp 56. A review by K. M. Reese on the presentation by Woods.
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Ian Hacking, The Emergence of Probability, Cambridge University Press, 1975.
James Franklin, Science of Conjecture, 2001.
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