Neuroscientific studies of CTE articulate the boundaries between cer- tainty and uncertainty through carefully constructed, sometimes com- peting, claims. Tagge et al. (2018) state that “while the pathogenesis of CTE is unknown, emerging evidence points to a putative causal associa- tion with neurotrauma” (p. 424). Asken et al. (2017) similarly write that
“exposure to [repetitive brain trauma] represents the greatest risk factor for CTE pathological features, although clinicopathological correlates and the nature of onset and progression of symptoms are largely unknown”
(p. 1261). Maroon et al. (2015) make similar claims, closing their review by asserting, “there is no credible data with which to establish the inci- dence or prevalence of CTE in former contact sport participants” (p. 12).
Scientific uncertainty functions differently through each statement about what is not known about CTE. Each claim identifies substantial knowl- edge gaps in the study of CTE, through which the authors offer varying assessments of how much is known about the condition. Most vividly, whereas Tagge and colleagues assert that unknowns around CTE onset should not discount evidence of the condition’s “putative causal relation- ship with neurotrauma,” Maroon and colleagues cite the same uncer- tainty around CTE risk factors but declare that “no credible data” exists linking the condition to collision sports.
The production of uncertainty is even more striking in the predomi- nance of causation as a scientific benchmark for conceptualizing how and why CTE develops. In a review of the existing scientific evidence on CTE, Solomon (2018) assesses and interprets an extensive list of CTE- related studies, concluding, “despite anecdotal and case series reports, it is my opinion that there is no compelling empirical evidence to indicate that sport-related concussion or subconcussive impacts are the sole and direct cause of psychiatric illness, suicide, mild cognitive impairment, or neurodegenerative disease/CTE” (p. 303, italics in original). The 2016
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Berlin Consensus Statement on Sport-Related Concussion similarly declares, “A cause-and-effect relationship has not yet been demonstrated between CTE and SRCs [sport-related concussion] or exposure to con- tact sports. As such, the notion that repeated concussion or subconcus- sive impacts cause CTE remains unknown” (McCrory et al. 2017, p. 7).
Both Solomon and the Berlin Consensus Statement dictate that scientific uncertainty around CTE stems from inadequate evidence of a causal link between the condition and brain trauma. Their matter-of-fact statements of uncertainty are not “false” and cannot be easily rebutted with the irre- futable proof of causation these authors seek; indeed, similar claims per- vade the neuroscientific CTE literature (e.g. Iverson et al. 2018; Schwab and Hazrati 2018). Such reliance on causal explanations is complicated by how philosophers of science contest the meaning of “causation” as a scientific and epistemological construct (e.g. Cartwright 2004). Yet the symbolic power of cause-and-effect relationships (or lack thereof), how- ever, remains central to the production of scientific uncertainty around CTE.
The very act of declaring and repeating these uncertain “truths” as part of the scientific record performs substantial political work in the produc- tion of uncertainty. These claims establish CTE causation as the scientific benchmark for conclusive “proof” of the long-term consequences of sport-related brain injury. The aforementioned statements about causa- tion (and similar examples) explicitly foreground the existence of
“unknowns” around CTE and can be cited in response to public concern about the risks of brain injury in collision sports. Unsurprisingly, uncer- tainty around CTE causation is a central theme of sports organizations’
efforts to deflect public criticism or avoid legal responsibility for the long- term effects of brain trauma (Benson 2017; Finkel and Bieniek 2018;
Goldberg 2012; Ventresca 2019).
The potential for sports stakeholders to opportunistically generate and exploit uncertainty as a public relations tactic is an example of how those in positions of power (e.g. governments, military, or corporations) can strategically construct scientific uncertainty for economic or political gain (Oreskes and Conway 2010; Pinto 2015; Proctor 2008; Zehr 2017).
Most commonly, this strategy involves employing compliant researchers to produce results casting doubt on prevailing scientific thinking around
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a controversial issue (such as climate change or smoking) to sway public opinion or delay political action. Scholars have highlighted how sports organizations have mobilized the production of scientific uncertainty as a tactic to “manufacture doubt” about the relationship between repetitive brain trauma and CTE (Bachynski and Goldberg 2014; Benson 2017;
Casper 2018a; Goldberg 2012; Ventresca 2019). Historian Stephen Casper (2018a) writes that the contemporary emphasis on CTE causa- tion conflicts with the lineage of research that, despite acknowledging a multitude of unanswered questions, decisively identified brain trauma as the source of neurodegenerative processes in athletes. Current uncer- tainty, according to Casper, is a recent invention of scientific and industry actors strategically neglecting this history of research in the interest of manufacturing doubt around the long-term effects of TBI. Skepticism around the role of the sports industry in shaping scientific results has been bolstered by studies uncovering conflicts of interest pervading research partnerships involving corporations such as the NFL (Bachynski and Goldberg 2018).
Yet uncertainty around CTE has also been enabled by shifting onto- epistemological foundations within neuroscience. Innovations in brain sensing and imaging technologies throughout the 1980s ushered in a
“neuroscientific turn” across the life sciences (Pitts-Taylor 2016). The concurrent emergence of a “neuromolecular style of thought” popular- ized the notion that all mental states and cognitive processes could be directly linked to activity within the brain detectable through neurosci- entific techniques (Rose and Abi-Rached 2013). Yet new potentials for neuroscientific precision also facilitate discursive space for uncertainty structured around the promise of determining exact causes and effects.
Put simply, belief in neuroscientific capacities to know more widens the field of what is not yet known. Scientists can represent the unhealthy brain as a site of uncertainty if precise neurophysiological processes elude the grasp of neuroscientific methods (Rose and Abi-Rached 2013). In doing so, the production of uncertainty around perceived neuroscientific capacities to reveal specific causes and effect reproduces evidence hierar- chies in which experiential knowledge is actively marginalized (Pitts- Taylor 2016).
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