Smallpox inoculation and demographic trends in eighteenth-century Scotland

The impact of inoculation on levels of mortality has always been a contentious issue.Was the practice of deliberately infecting patients with a mild case of smallpox so as to produce immunity to further attacks the first of a triumphal succession of techniques by which medical men conquered infectious diseases, or a dangerous procedure of little or no value?Historically, opinions have swung back and forth.Eighteenth-century medical men and early demographers were convinced that it was the greatest medical improvement of the age.In 1782, John Howlett concluded that the increase in population he had observed in parish records was due "chiefly to that distinguished blessing of providence, inoculation".'A number of early nineteenth-century writers, including Arthur Young and John Heysham, also attributed reduced mortality and rising population to the practice.2By this time, however, inoculation was beginning to fall under a cloud, as proponents of vaccination sought to discredit the procedure, arguing that inoculated persons transmitted smallpox to the healthy and thus actually spread the disease.In the twentieth century, historians and demographers have continued to debate the impact of inoculation on mortality.Initially, it was viewed unproblematically as one of an array of medical measures, including hospitals, dispensaries and new drugs, which contributed to increased life expectancy.3In the 1960s, however, conflicting interpretations were put forward and opinions remain divided.The thesis that inoculation had, at best, a minor effect on mortality levels was first stated by Thomas McKeown and R. G. Brown.They challenged the role of medicine in reducing death rates, pointing out that the greatest number of deaths was due to infectious diseases, which practitioners were powerless to treat.Inoculation was the sole exception