Defoe’s Journal

Journal of the Plague Year E. Nutt 1722

being Observations or Memorials
of the most remarkable occurrences,
as well public as private, which happened in
London during the last great visitation in 1665.
Written by a CITIZEN who continued
all the while in London.
Never made publick before.

This work is presented as an account by ‘H.F’, possibly Henry Foe, the uncle of Daniel Defoe , but may simply be an imaginative reconstruction by Defoe of what may have happened, based on his later enquiries and his insights from his own interesting life as a spy and conspirator of mixed fortunes. Some of the details may have been made up to make a good story, but it is still of interest, notably for:

I mention this story also as the best method I can advise any person to take in such a case, especially if he be one that makes conscience of his duty, and would be directed what to do in it, namely, that he should keep his eye upon the particular providences which occur at that time, and look upon them complexly, as they regard one another, and as all together regard the question before him: and then, I think, he may safely take them for intimations from Heaven of what is his unquestioned duty to do in such a case; I mean as to going away from or staying in the place where we dwell, when visited with an infectious distemper.

I shall ignore the theological and historical aspects and ask ‘is this good guidance more generally’, from my own mathematical viewpoint? The above advice contrasts with the most common conceptualisations, that rely on applying norms soundly based on past experience rather than the current particulars. Mathematically, this challenges not only much use of both calculus and probability, both in their infancy in Defoe’s time, but also the possibility of relying unconditionally on any prior theory or model, no matter how logical, when there is no possibility of a prior knowledge forming a ‘closed category’; or to put it another way, when faced with novel experiences, not just a variation on those experiences which informed prior judgements and expectations, and for which one may be prepared.

The account does include the story of a soldier who puts his experienced of epidemics gained abroad to good use, but the narrator’s own story is much more interesting as he grapple with huge and critical uncertainties. For example, while soaking one’s clothes in vinegar seems effective he notes that so too does eating raw garlic, and considers the possibility that the seeming life-preserving effects may be the aid to social distancing that is important as against any disinfectant effect. Thus while providing an example of his advice, as above, he also illustrates the benefits of keeping an open, cautious and sceptical view of the opinions and example of others without suffering from ‘paralysis by analysis’.

Dave Marsay

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