Mechanical Epistemic Injustice

 In this post, Coreen McGuire adapts her concept of mechanical epistemic injustice to the Post Office/Horizon scandal. 

Image credit: 'Boxes, Kimpton, Hampshire', by Mike Cattell.

A harrowing scene in the ITV drama, ‘Mr Bates vs. the Post Office’, depicts Mr Lee Castleton, a Sub-Postmaster accused of stealing money from the Post Office, arguing in court that he hasn’t done anything of the sort. Rather, faulty Fujitsu’s Horizon software is creating imaginary deficits. Desperate to be believed, he asserts that the ‘system produces them out of nowhere’. Against his testimony, an expert maintains that no evidence suggests any problems with the computer software. The viewer and Mr Castleton both know that he was in fact correct, but he is not believed. The objectivity of the software is venerated, and elevated above his testimony. The show’s depiction of the visceral unfairness of this created public outrage that has sparked a public inquiry and attempts to redress victims — sadly still ongoing. The specific way that the victims of the Postmaster scandal were wronged exemplifies a type of mechanical epistemic injustice in which technologies are used to disenfranchise knowers.

In my 2020 book, Measuring Difference, Numbering Normal, I coined the term ‘mechanical epistemic injustice’ to describe how the objectivity associated with technology is valued over and above individuals’ claims about their own health. Following Miranda Fricker’s 2007 account of epistemic injustice, mechanical epistemic injustice extends this theory to denote how people are harmed when technologies are accredited undue epistemic credibility. My book considers hearing loss and breathlessness, intimate and invisible experiences that have historically been associated with malingering and disbelief. Considering the technologies that have been used to make these personal experiences legible and compensable reveals that such tools have also been used to deny personal experiences of disability. And a long view of the Post Office emphasises how wielding mechanical epistemic injustice has historically allowed institutions to avoid making changes to their systems. 

In the interwar era, the nationalised Post Office used a device called the artificial ear to set the standards for normal hearing that their telephones were tested against. By equating idealised hearing with average hearing, they artificially elevated this standard and created a new cohort of ‘hard-of-hearing’ subscribers, who had to pay increased monthly rental for a ‘telephone for the deaf’ service. Despite not experiencing significant problems with hearing loss in other areas of their lives and despite protesting that the problems were systemic, these subscribers were told that any problems they had were due to their individual hearing loss, not the Post Office technology. Pathocentric epistemic injustice linked to their disability intersected with mechanical epistemic injustice to effectively silence these subscribers.

The example of the spirometer clarifies how mechanical epistemic injustice perpetrates harms in healthcare settings. The spirometer is a device designed to make a ‘proxy’ measure of lung capacity by estimating ‘vital capacity’. It ‘corrects’ for various individual variables that may impact on lung capacity, including demographic factors whose health effects have long been disputed. The elevation of contentious individual factors like sex or race or class, has worked to obscure the impact of environmental factors on lung function and locate the responsibility for health within the individual rather than in the environmental conditions surrounding them, such as pollution or poverty or industrial conditions. This meant that for groups whose work impacted on their lung function – like miners – the spirometer became central to the perpetuation of mechanical epistemic injustice. Miners knew that the dust they were inhaling was making them ill, but tools like the spirometer failed to recognise their disability and were used to justify withholding compensation from certain affected individuals.

Mechanical epistemic injustice is an especially useful way to think about the harms that were visited on the sub-postmasters through the British Post Office Scandal because it can help us think more clearly about responsibility when machines are used to replace human thinking. Thinking about the limits of technological agency and paying attention to the way it was mobilised to apportion blame and then to avoid responsibility means mechanical epistemic injustice can clarify the real responsibilities and culpabilities of both Fujitsu and key individuals working in the Post Office.

References

• Braun, L., Breathing Race into the Machine: The Surprising Career of the Spirometer from Plantation to Genetics (Minneapolis: University of Minnesota Press, 2014).
• Flinders, K. (2024). ‘Post Office Horizon scandal explained: Everything you need toknow’. Computer Weekly. Accessed August 2026.
• Fricker, M, Epistemic Injustice: Power and the Ethics of Knowing (Oxford: Oxford University Press, 2007).
• McGuire, C., Measuring difference, numbering normal: Setting the standards for disability in the interwar period. (Manchester: Manchester University Press, 2020)
• McGuire, C. (2019). ‘X-rays don’t tell lies’: the Medical Research Council and the measurement of respiratory disability, 1936–1945. The British Journal for the History of Science, 52(3), 447-465.

Coreen McGuire is Associate Professor in Twentieth-Century British History at Durham University. She is the author of Measuring Difference, Numbering Normal: Setting the standards for disability in the interwar period and co-editor of Epidemiological Obfuscation: Historical and Contemporary Case Studies. Her current research focuses on the development of categories used to organise data to measure disability and this work is supported by a Wellcome University Award. She is co-editor of the Disability History series for Manchester University Press and leads ‘The Measurement Lab’ at Durham University’s Institute for Medical Humanities.