![Sample our Social Sciences journals, sign in here to start your FREE access for 14 days]({"type":"image" , "src" : "/sda/110822/TOC-Subject-Sample-2021-Social-Sciences.jpg"})
Abstract
Risk assessment studies often adopt a quantitative approach and analyse decisions or judgements in relation to risk at one specific point in time. These studies certainly have their merits but their preponderance in the literature on risk has been to the exclusion of qualitative studies that seek to examine judgements of subjects over an extended period of time. I seek to redress this imbalance by examining how scientists assessed risk in the context of a significant public health problem in the UK: the emergence of bovine spongiform encephalopathy (BSE) in cattle. This disease first emerged in British cattle in 1986. Yet over 20 years on, its implications for human health are still being assessed by scientists. In this paper, I examine the reasoning strategies that scientists employed to make risk assessments in relation to BSE in the period between 1986 and 1996. Two arguments in particular (analogical argument and the argument from ignorance) were the mainstay of scientific reasoning in the period under investigation. The rational standing of these arguments varied over time in relation to evidence that was emerging from experimental and other studies. It is argued that it is not possible to capture the factors which are necessary to understanding scientific risk assessments in relation to BSE within the type of quantitative, static study that is typically pursued within research on risk.
Notes
1. One of the key scientific committees that were established by the British government to assess the risks posed by BSE to human health, the Spongiform Encephalopathy Advisory Committee (SEAC), is still undertaking risk assessments in relation to BSE. The minutes of SEAC's eighty-seventh meeting show that SEAC was still addressing the risks of blood transfusion-associated transmission of variant Creutzfeldt-Jakob disease (vCJD) in April 2005, nearly 10 years after the period that we are considering in this paper (vCJD is a new human TSE which has been caused by BSE).
2. Iatrogenic transmission of CJD (transmission through some form of medical treatment or surgery) has permitted the calculation of specific incubation periods for this disease. ‘Central inoculation through neurosurgery, depth electrodes, corneal graft or dura mater graft results in disease after a mean incubation period of about two year … Peripheral inoculation through human pituitary derived growth hormone (hGH) or pituitary derived gonadotrophin (hGnH) results in disease after an incubation period range from a minimum of four year to a maximum of at least 30 year with a mean of around 12 year' (Will 1993, p. 963).
3. The standard list includes the fallacies that Woods et al. (2004) have described as the ‘gang of eighteen’. These fallacies include ad baculum, ad hominem, ad misericordiam, ad populum, ad verecundiam, ad ignorantiam, post hoc ergo propter hoc, affirming the consequent, denying the antecedent, begging the question, equivocation, amphiboly, hasty generalisation, biased statistics, composition and division, faulty analogy, gambler's fallacy and ignoratio elenchi.
4. ‘[W]e show how simple building blocks that control information search, stop search, and make decisions can be put together to form classes of heuristics, including: ignorance-based and one-reason decision making for choice, elimination models for categorisation, and satisficing heuristics for sequential search. These simple heuristics perform comparably to more complex algorithms, particularly when generalising to new data – that is, simplicity leads to robustness’ (Todd and Gigerenzer 2000, p. 727).
5. Johnson and Blair (1994, p. 34) capture the essence of the principle of charity as follows: ‘[Y]our objective is to add to the stated premises the most plausible statement (consistent with the rest of the passage and likely to be believed by the arguer and used in addressing that audience) needed to make the whole set of premises relevant to the conclusion’.
6. The Southwood Working Party was established on the recommendation of Sir Donald Acheson (Chief Medical Officer, 1983–1991) ‘to advise on the implications of Bovine Spongiform Encephalopathy and matters relating thereto’ (BSE Inquiry 2000c, p. 2). The Working Party consisted of experts in human and animal health. Its members were Sir Richard Southwood (Chairman of the Working Party and a professor of zoology), Anthony Epstein (a professor of virology), Sir John Walton (a clinical neurologist) and Dr William B. Martin (a veterinarian).
7. The Lord Phillips inquiry notes that ‘[e]xtensive investigation of scrapie has taken place in Great Britain since the 1940s. Indeed, Great Britain did, and still does, possess several leading institutions for research into diseases of sheep and spongiform encephalopathies’ (BSE Inquiry 2000b, p. 22).
8. ‘In the later stages of [scrapie] the fabric of the brain is attacked. The pathologist can diagnose the disease by the spongiform appearance of the diseased brain. At the end of 1986 pathologists at the Central Veterinary Laboratory (CVL) identified similar degenerative changes in the brain samples of diseased cattle from two different herds. These were early cases of BSE’ (BSE Inquiry 2000a, p. 13).
9. ‘Strain-typing showed that, in contrast to scrapie, which had a number of different strains, cases of BSE from different parts of the United Kingdom and in different years were indistinguishable from each other but distinct from all previously studied laboratory strains of scrapie’ (BSE Inquiry 2000a, p. 139).
10. Dr Richard Kimberlin was a TSE research scientist at the Neuropathogenesis Unit in Edinburgh between 1981 and 1988. Since 1988, he was an independent TSE consultant. During the BSE crisis, he was a member of the Tyrrell Committee (an expert committee that was set up to recommend research priorities for BSE) and the Spongiform Encephalopathy Advisory Committee.
11. The ‘no reason’ and ‘no (scientific) justification’ variants of the argument from ignorance are demonstrated by the following extracts, both of which represent the reasoning of the Spongiform Encephalopathy Advisory Committee (SEAC): ‘When Mr. Dorrell made his statement to Parliament, he was unable to answer an obvious question. Were children more susceptible than adults to BSE? All that he could say was that he had asked SEAC to advise on this. In the event SEAC advised that there was no reason to believe that children were particularly susceptible’ (BSE Inquiry 2000a, p. 164; italics added). ‘In our [SEAC's] judgement any risk as a result of eating beef or beef products is minute. Thus we believe that there is no scientific justification for not eating British beef and that it can be eaten by everyone’ (BSE Inquiry 2000a, p. 131; italics added).
12. The Public Health Laboratory Service was an established service for the surveillance of new and existing diseases in the UK. On the recommendation of the Southwood Working Party, a new body was established to identify atypical cases or changing patterns of CJD (it was believed that if BSE were to transmit to humans, it would most likely manifest as CJD). The CJD Surveillance Unit (CJDSU) was formed. The decision to establish this unit was vindicated when CJDSU subsequently detected the first cases of vCJD.
13. Where an exhaustive search of a closed knowledge base has been undertaken, the argument from ignorance is deductively valid. Walton (1992, pp. 385–386) captures the deductive form of this argument as follows: ‘To the extent we know a knowledge-based K is closed, i.e., complete, in the sense of containing all the relevant information, we can infer that if a proposition A is not in it, then A is false. This argumentation scheme for the argumentum ad ignorantiam has the following form:All the true propositions in domain D of knowledge are contained in K.A is in D.A is not in K.For all A in D, A is either true or false.Therefore, A is false.This form of inference is deductively valid'.
14. A pathogenesis study that had been initiated at the Central Veterinary Laboratory (CVL) in December 1991 revealed infectivity in bovine tissues (e.g. ileum) earlier than had been expected using the scrapie model (BSE Inquiry 2000b, p. 121).
15. Section 4 committees were so named on account of their establishment under Section 4 of the Medicines Act 1968. These committees consisted of eminent outside experts who provided advice to the Medicines Division (the body that was responsible for the licensing of medicines in the UK) within the Department of Health.
16. Dr Raine, Medical Assessor to the Committee on Dental and Surgical Materials, prepared a paper for the first meeting of the BSEWG. In this paper, she outlined the extent to which Ethicon, the major UK manufacturer of surgical catgut, used bovine material in its production: ‘90% of Ethicon catgut is manufactured from bovine serosal tissue, the balance being ovine sub-mucosal material. The requirement for raw material is 25 million meters per annum, originating from 550,000 cattle (13% of the UK cattle kill from 18 abattoirs distributed throughout the UK). One animal yields about 45 meters of intestine and the catgut manufacturing plant requires the input from 2,500 animals per day' (BSE Inquiry 2000e, p. 151).
17. Sir Donald Acheson (Chief Medical Officer, 1983–1991) told Lord Phillips and his team: ‘I had in mind a marked and extended previous reduction in the acceptance of whooping cough vaccine which had followed incorrect public allegations by a scientist that the administration of the vaccine carried a significant risk of encephalitis. On the other hand I was aware that during the period 1980–1988, due to incomplete vaccination of our population of children, there had been 123 deaths from measles and 50 from whooping cough in England, together with a many times larger burden of illness and some long-term complications' (BSE Inquiry 2000a, p. 179).
18. This is a rejoinder to comments made by Lord Phillips and his team in response to the first case of FSE: ‘The public was likely to conclude that the cat had caught BSE from eating contaminated beef. And if this could happen to a cat, why should not human beings suffer the same fate? Yet it was far too soon to jump to any such conclusion. It was possible that there had always been the occasional case of feline spongiform encephalopathy (FSE) which had gone unrecognised’ (BSE Inquiry 2000a, p. 128).