Defoe’s Journal of the Plague Year: a study of risk management

COVID-19 has led to renewed interest in descriptions of earlier plagues.¹ In some of these accounts, the authors’ intentions extend beyond a description of the plague and its consequences. Thus The Plague (1947) by Albert Camus has been seen as an allegory in which the human consequences of the bubonic plague also represent those of the plague of fascism, and Daniel Defoe’s Journal of the Plague Year (1722) can also be read as a study of risk management in a time of crisis, a study in which the validity of the experiential observations of one man are contrasted with those derived from official statistical data.

Defoe’s interests in risk and probability may have stemmed from his time as a businessman and an accountant. It was a topic which he had previously addressed in An Address upon Projects (1697) and one to which he would return in A Plan of the English Commerce (1728). It also featured in a number of his more fictional works including Robinson Crusoe, Moll Flanders and several times in the Journal, most notably when the narrator, ‘H.F.’ weighs the pros and cons of leaving London for his personal safety or remaining to safeguard his business.²

The Enlightenment was a time of renewed interest in risk and probability and this period of interest is often dated to the exchange of letters between Pascal and Fermat on the possible outcomes of a game of dice in 1654,³ only 11 years before the Great Plague. Interest in commercial risk was greatly stimulated by the South Sea Bubble in 1720, just two years before publication of the Journal which was itself primarily a response to concerns generated by the arrival of the plague in Marseilles.

The Journal purports to be that of ‘H.F.’, a London saddler who may have been Henry Foe, Defoe’s uncle who was himself a London saddler. However, one of the Journal’s sources has been identified as Loimologia by Nathaniel Hodges, FRCP, published in Latin in 1671 but not translated into English until 1720. It seems improbable that a London saddler would have been able to read this in the mid-1600s or would have had the leisure to have analysed the Bills of Mortality which are quoted extensively in the Journal. Perhaps Defoe had access to a lost memorial written by his uncle but to all intents and purposes the Journal is his own work. Indeed, analysis of Defoe’s historical works has suggested that he conceived of fiction as a legitimate strategy in historical representation and the addition of ‘H.F.’ may simply have been used to lend verisimilitude to a fictional saddler’s account.⁴

Using H.F. as his mouthpiece Defoe, who was about five years old at the time of London’s Great Plague of 1665, creates a dichotomy between the observations of H.F and the numbers of deaths published in the Bills of Mortality. The latter appeared weekly with an annual summary. Those for the time of this plague were published in 1665 by Ellen Cotes as London’s Dreadful Visitation. H.F. quotes from the Bills, stating repeatedly that the official data do not accord with his own observations as he walks the city’s streets and that they seriously underestimate the deaths due to plague. He gives two main reasons for the underestimates. First, the appalling circumstances and sheer number of deaths made it impossible to keep an accurate account: ‘…’tis certain they died by Heaps, and were buried by Heaps, that is to say without Account’. Second, those responsible for assigning a cause of death could be bribed to ascribe a death to a cause other than plague so that other members of the household would not be forcibly quarantined in their own homes with a red cross on the barred door for all to see. In consequence, the numbers of non-plague deaths were artificially inflated.

It can be no coincidence that exactly these same observations about earlier plagues, observations that had also been derived from the Bills of Mortality, had been published in 1662 by Henry Graunt, a London haberdasher.⁵ However Graunt had recognised that corrections could be made for the sources of inaccuracy by examining all deaths, and not only those attributed to plague, and by making comparisons with non-epidemic years. In this way, he had thought it possible to keep ‘sufficient and useful Accompts’ and calculated that ‘about a ¼ part more died of the Plague than are returned as such’.

To conclude, Defoe’s Journal is not only a description of the plague in 1665 but also an informed layman’s thoughts on the latest statistical epistemology in the early 18th century. His emphasis, through H.F., on the superiority of experiential observation over data of uncertain providence suggests that he was influenced more by Lockeian empiricism than by the nascent statistical methods promoted by John Graunt and his friend William Petty. This tension is one which has persisted down the centuries. A notable example occurred in 1879 in response to Lister’s introduction of antiseptic techniques in surgery when the Lancet opined that: ‘It does not seem to us by any means plain that the value of Lister’s system … can be determined by the figures, but must be referred to the accumulating conviction of individual surgeons’.⁶