Singularities and Universals: Case Reports, Clinical Trials, and an Enduring Epistemic Tension

Abstract

This manuscript examines how distinct epistemic attitudes toward singularity and generality have been articulated in medical writing across different historical contexts, offering a conceptual and meta-historical analysis of two enduring genres in biomedical literature: the individualized case report and the systematically aggregated clinical trial. Hippocratic case narratives are considered as a particularly lucid articulation of a mode of inquiry that privileges detailed observation of individual patients, while medieval Aristotelian natural philosophy exemplifies a contrasting emphasis on regularity, intelligibility, and general explanation. Renaissance medical and philosophical traditions are treated as a mediating moment in which attention to anomaly, wonder, and singularity was explicitly re-legitimized within learned medicine. These historically situated articulations are not presented as stages in a progressive narrative, but as recurrent epistemic orientations that are repeatedly reconfigured under different theoretical, institutional, and technological conditions. The paper argues that the tension between attention to exceptional cases and the pursuit of generalizable knowledge continues to structure modern biomedical writing, where case reports remain essential for identifying rare, novel, or anomalous phenomena, while clinical trials formalize strategies for producing reproducible, population-level evidence.

1. Charting the Poles: Singularity and Universality in Medical Knowledge

The story of medicine is, in large measure, the story of how healers arrange what they know. Hippocratic physicians once filled wax tablets with the minutiae of a single fever, convinced that every cough or chill might matter (Van der Eijk 2016); twenty-first-century investigators, by contrast, marshal randomized controlled trials (RCT) that pool data from tens of thousands of volunteers (Umscheid et al. 2011). Across the centuries, practice has swung between two magnetic poles: the singular life unfolding before the healer and the abstract regularities that emerge only when many such lives are considered together. This oscillation recalls Edmund Husserl’s (1859–1938) interpretation in The Crisis of the European Sciences of the modern scientific science’s tension between the Lebenswelt—the world as immediately given in lived experience—and the abstract, mathematized order that seeks to represent it (Husserl 1970). In both medicine and philosophy, the move from the concrete to the formal promises universality but risks losing contact with the phenomena that first made knowledge possible. This is no idle methodological debate. It reflects the basic ways human beings try to make sense of flesh, illness, and chance. Even in an era that prizes p-values and meta-analyses, the well-crafted case report still earns attention when it reveals a presentation no textbook predicted or hints at a mechanism no algorithm has yet discerned (Albrecht et al. 2009).

What appears, in retrospect, as a tug-of-war between the particular and the general reaches far back1. From Aristotle (384–322 BCE) to the scholastics, physicians and philosophers sought constancy: stable categories and reliable causal chains through which to read nature (Arlig 2020). Yet even as they prized order, they never ceased to marvel at the irregular: the monstrous birth, the sudden recovery, the singular case that defied expectation (Stein 2011). Renaissance writers, reclaiming this fascination, compiled paradoxographies—catalogs of marvels and monsters—turning anomalies into objects of learned curiosity. The Hippocratic corpus had already gestured toward that balance, showing that careful narrative—attentive to climate, diet, and temperament—could illuminate disease as powerfully as general theory (Kalachanis and Tsagkaris 2020). The mechanical worldview of Galileo (1564–1642) and Descartes (1596–1650) later renewed the pursuit of universal laws, but never fully silenced the intuition that every individual body is its own small cosmos (Henry 2004).

These precedents helped shape the two reporting traditions that medicine still holds in tension. When a clinician confronts an unexpected rash or an inexplicable laboratory result, a single documented case can upend comfortable assumptions, spark a new hypothesis, or even unveil a previously unnamed syndrome (Vandenbroucke 1999). Yet the same clinician turns to aggregate trial data when prescribing, confident that broad reproducibility will better guard patients against the seductive hazards of anecdote (Sedgwick 2015). The coexistence of these strategies—one attuned to the exceptional, the other oriented toward averaged effects—has informed editorial policies, training curricula, and hierarchies of evidence that structure contemporary care, healthcare governance, and biomedical research.

In this paper, Hippocratic medicine is not invoked as the origin of modern biomedical practices, nor as an early stage in a linear narrative of progress. Rather, Hippocratic case narratives are treated as an early and particularly lucid articulation of an epistemic posture; one that accords singular observation a legitimate role in knowledge production. This posture is repeatedly reconfigured, constrained, or partially displaced across historical periods, but it is never fully eliminated.

This paper threads those legacies through two literary forms that dominate biomedical discourse: the case report and the clinical trial. By following their trajectories through medieval lecture halls and Renaissance cabinets of curiosity, to modern journals and registries, we aim to expose both the deep kinship and the persistent friction between them2. Conceptual frameworks assembled centuries ago continue to structure contemporary research practices, reminding us that the pursuit of health has always balanced the universal promise of pattern against the revelatory power of singular experience.

2. Between Vignette and Aggregate: Genres of Biomedical Evidence

Case reports stand at the intimate, bedside end of scientific communication (Vandenbroucke 2001). They chronicle the encounter between a single patient and a clinician, weaving history, examination, investigation, treatment and outcome into a short narrative that attempts to capture lived particularity (Nissen and Wynn 2014). Typically, no statistics appear beyond a timeline; the authority of the paper rests on circumstantial richness—age, occupation, comorbidities, laboratory trajectories—and on the clinician’s judgment that something about this individual diverges from expectation (Lysanets et al. 2017). Since at least the 17th-century Philosophical Transactions, editors have prized such vignettes for at least one chief reason: they possess hypothesis-generating power (Rodriguez and Zimmerman 2021). An unexpected drug reaction, a puzzling constellation of symptoms, the first human infection—none of these can initially be verified in groups, because the phenomenon is still singular. The narrative therefore functions as an early warning system, inviting the community either to replicate the observation or to fold it back into established classifications (Morris 1989). Modern guidance such as the CARE statement (Gagnier et al. 2014) formalizes that narrative but retains its essence: exposition of a clinical surprise in the hope that the anomaly will illuminate a wider field.

Clinical trials—and in their most stringent form, RCTs—were devised to temper the very quirks that make case reports so compelling (Friedman et al. 2015). By recruiting large numbers of participants, these studies dilute individual anomalies through sheer statistical force (Julious 2004). In an RCT, randomization, blinding, and careful power calculations ensure that outlier responses are evenly distributed across treatment arms, minimizing their undue influence (Friedman et al. 2015; Baghbaninaghadehi et al. 2016). The result is an average treatment effect: a construct that approximates the “universal” ideal traced back to Aristotle. When dozens, hundreds, or thousands of patients on a certain drug outperform those on placebo, that finding is treated as generalizable to any future patient who fits the trial’s eligibility profile (Stuart et al. 2015). The rhetorical structure of the RCT reflects that ambition. Method sections overshadow the vignette-like background; patient stories are compressed into inclusion criteria; outcomes appear not as plot twists but as p-values and confidence intervals (Simpson et al. 2010). The CONSORT guidelines, first issued in 1996 and revised in 2010, codify that impersonality, demanding flow diagrams that track subjects as interchangeable datapoints migrating through allocation and analysis (Altman et al. 2001).

Observational cohort and longitudinal studies occupy a middle ground. They forego the experimental act of randomization yet still recruit groups large enough to model variation statistically (Jepsen 2004). In a prospective cohort that follows smokers and non-smokers for 20 years, no single biography dominates; each participant contributes a sliver of person-time that melds into rates and hazard ratios (Steventon et al. 2015). The STROBE statement underscores this statistical ethos, urging clarity about confounding variables and loss to follow-up so that the collective signal can rise above individual noise (von Elm et al. 2007). Where a case report proclaims “here is an exception,” and an RCT declares “here is the rule,” an observational study suggests “here is the tendency.” The epistemic distance between tendency and rule may be narrow in mathematics, yet in clinical reasoning it maps onto a profound divide: should physicians treat the patient before them as a datapoint in a population curve or as a potentially unrepeatable constellation of circumstances?

Because each genre answers that question differently, their publication formats reinforce the ancient polarity between singular and universal. The case report’s narrative arc mirrors Aristotle’s “particular,” while the RCT’s statistical tables echo his “universal” by abstracting particulars into essences. Even the language betrays the divide. Case reports are often written in the active voice of the bedside narration—“we observed,” “the patient improved”—(Lysanets et al. 2017) whereas RCTs and cohorts retreat into passive constructions that efface author and subject alike (Phadtare et al. 2009). Editorial economies follow suit: high-impact journals, wedded to metrics such as impact factor and generalizability, devote most pages to trials, relegating case reports to brief communications or specialized outlets (Brighton et al. 2003). Yet the prestige hierarchy remains contingent. When new syndrome erupted—AIDS in 1981, SARS in 2003, COVID-19 in 2019—the first papers the world read were invariably case reports, because nothing else yet existed (Williams et al. 2013; Wang et al. 2021; Carey 2010).

The dialectic is therefore methodological and temporal. Individually focused writing appears early in the life cycle of discovery, while aggregate studies emerge later to test, quantify and generalize. Precision medicine and “n-of-1” trial designs are beginning to collapse that chronology by embedding crossover experiments within single patients, turning the body into its own micro-cohort and blurring case narrative with controlled trial (Gabler et al. 2011). Still, the conceptual opposition endures: averaging strives for a view from nowhere; storytelling binds knowledge to a person, a place, a moment (Kirmayer et al. 2023). Biomedical literature needs both modes. Without aggregation, treatment would remain a litany of anecdotes; without anomalies, averages would ossify into complacent dogma. The section that follows returns to antiquity to show how this tension first arose, but the modern publishing landscape already reveals its pulse in every table of contents, from the solitary drama of a reversed anticoagulant overdose to the grand chorus of a multinational phase-III trial.

3. Hippocratic Observations and the Birth of Case Narratives

The origin of Western medical thought is often traced to the Hippocratic corpus, a collection of texts from the late 5th century BCE and onward (Van der Eijk 2016). Though penned by many hands, these texts together marked a decisive turn: illness became a matter of nature rather than of offended gods (Orfanos 2007). A notable feature within this corpus is the prominence of case histories: meticulously detailed reports of individual patients, their environments, presenting symptoms, and disease courses (Kazantzidis 2018). In the Epidemics narratives we glimpse real people, embedded in climate and community, their progress followed with almost diaristic care: proof that one life could illuminate the wider logic of disease (Pormann 2012).

Such devotion to the individual served intertwined aims (Thumiger 2015). By rooting theory in bedside particulars, Hippocratic authors offered practical counsel to physicians who met every variety of patient in polis and countryside alike (Bottalico et al. 2019). At the same time, the steady accumulation of these stories became an early engine of induction: patterns emerged not from armchair speculation but from lived experience, allowing the healer to edge from the unique toward the general (van Schaik 2018). Within this humoral framework, however, generalization did not mean aggregation across cases or statistical comparison, but the articulation of explanatory principles governing balance, temperament, and individual variation.

The humoral framework that organized Hippocratic thought—an ever-shifting balance of blood, phlegm, yellow bile and black bile—reinforced this commitment to difference (Balzer and Eleftheriadis 1991). Because each constitution was believed to tilt the humors in its own way, no two fevers or wounds could be read quite alike; every encounter promised a fresh nuance. That habit of close watching seeded later medical genres, legitimizing the practice of writing down what happened to just one person and treating the report as evidence rather than curiosity.

To modern readers the blend of minute observation and speculative physiology can feel disconcerting, yet the underlying lesson endures. Every patient, ordinary or bizarre, still has something to teach about the fragile human body. These case narratives were not intended to establish diseases as autonomous entities, but to cultivate practical judgment through singular exemplars. Indeed, within humoral medicine, illness was necessarily individualized, since pathology was understood as a constitution-specific imbalance rather than the action of a stable disease entity; comparability across patients was therefore limited in principle, not by lack of observation but by theoretical commitment. Contemporary case reports—now framed by sophisticated diagnostic tools—draw on the same Hippocratic impulse to capture the unexpected, trusting that tomorrow’s broader theory may spring from today’s singular tale.

4. Scholastic Order and Preternatural Anomalies

With the collapse of the Roman Empire and the rise of medieval scholasticism, Aristotelian philosophy became the dominant lens through which many forms of knowledge, including medicine, were interpreted in the Latin West (Cadden 2013). Aristotle’s works, transmitted through Arabic philosophers such as Avicenna and Averroes (1126–1198), emphasized causality, classification, and the search for universal principles (Alagab 2025). In the medieval university, medicine was taught alongside natural philosophy under the guiding assumption that nature operated according to discoverable laws and hierarchies (Weisheipl 1964; Fletcher 1994).

In this intellectual environment, the study of individual cases could at times be subsumed under the quest for the generalizable. Medical treatises often sought to reconcile practical observations with Aristotelian categories. Diseases were classified according to their characteristics, etiologies, and humoral imbalances, but the overarching aim was to fit these conditions into a coherent theoretical framework that aligned with scholastic logic (Modell 2010). In this context, the “general” referred to theoretical intelligibility within Aristotelian causation, not to population-level regularities or statistical aggregation. When medieval physicians did record singular cases, it was frequently to illustrate a general principle rather than to highlight an exception (Maclean 2000).

Nonetheless, particularities did not entirely vanish. Medical commentaries on Aristotle’s texts and on the Hippocratic corpus often included personal observations (Kibre 1945). However, the prevailing scholastic mindset valued a universalizing approach that attempted to show how observed phenomena conformed to established philosophical doctrine (MacKinney 1952). The influence of authoritative figures—Galen (129–c. 216 CE), Avicenna (980–1037), Hippocrates (c. 460–370 BCE)—further codified the notion that individual observations must be placed in the context of accepted theoretical norms.

This medieval emphasis on the universal forged a path that would eventually intersect with the dawn of modern science. The drive to categorize nature systematically, gleaned in large part from Aristotle, played a significant role in shaping the intellectual milieu of later thinkers during the Scientific Revolution (Kvasz 1999). Yet, even in this period, there remained an undercurrent of fascination with anomalies and exceptions, as medieval bestiaries or miracle accounts demonstrate (Salisbury 2022). These were often relegated to the status of curiosities or moral allegories rather than objects of rigorous study, reflecting the scholastic preference for organizing knowledge into tidy, universal categories (Friedman 2000). Beyond the Latin West, 9th- and 10th-century physicians of the Islamic Golden Age cultivated a robust tradition of case-based empiricism (Renima et al. 2016). Muḥammad ibn Zakariyyā al-Rāzī (Rhazes, 865–925) organized more than 900 patient narratives into his 23-volume Kitāb al-Ḥāwī fī al-ṭibb (Comprehensive Book of Medicine), whose Latin translation, the Continens Rasis of 1279, became indispensable from Salerno to Montpellier (Ansari 1977). Individual fevers treated in Baghdad’s bīmāristāns sit side by side with theoretical chapters, and this is a useful reminder that sophisticated case reporting flourished in a multilingual, pan-Mediterranean milieu, not only in Renaissance Europe. A century later Ibn Sīnā’s Canon of Medicine (completed 1025) fused these anecdotes to an Aristotelian architecture of causes, and its authority in Parisian faculties by 1250 shows how clinicians toggled between particular and universal across cultural frontiers (Masic 2012). As these intellectual traditions converged in medieval Europe, physicians and theologians inherited a subtle lexicon for describing the limits of nature and the origins of wonder. Within this vocabulary, mirabilia, miracula, and monstra were distinguished by both origin and audience. Miracula were the works of God and thus wonderful to all; mirabilia issued from hidden but natural causes and astonished only the uninstructed; and monstra marked nature’s “error,” the product of matter’s resistance to form. This tripartite scheme was not merely semantic; it mapped the boundaries of legitimate inquiry. In scholastic medicine the triplet signaled degrees of explanatory reach: a monstrous birth was accidental, a marvel diagnostic, a miracle beyond art (Daston 1998b). A physician could legitimately dissect a monstrum to trace its material cause, whereas a miraculum belonged to divine economy. This semantic hierarchy foreshadowed the later medical habit of treating anomalies as clues for further study rather than as portents, acting as a crucial step toward the empirical case report.

High-medieval philosophers did not imagine an immutable, law-bound cosmos. They spoke instead of habitus and inclinations: habits that usually guide nature yet sometimes misfire (Nederman 1990). Thomas Aquinas (1225–1274) condenses the idea in Summa contra gentiles III: a double-headed calf is “accidental,” arising when matter or circumstance thwarts the artisan-like “intention” of nature (Aquinas et al. 1975). Such departures were neither diabolical nor meaningless: they occupied an intermediate, preternatural zone that challenged the physician and theologian alike to discover secondary causes without invoking direct divine interruption (Wood 2022). Medieval natural philosophers inherited from Aquinas a tripartite order of causality—natural, preternatural, and supernatural—that quietly structured the learned response to wonder. Natural effects were those that occurred “always or for the most part”; supernatural ones were divine miracles performed without secondary causes; and between them lay the preternatural, the realm of the rare yet still natural event (praeter naturae ordinem). It was here that most mirabilia resided: prodigious yet explicable, demanding inquiry rather than worship. The preternatural belonged neither to theology nor to routine physics but to an intermediate epistemic zone that sustained curiosity itself (Daston 1998b). Marvels provoked stupor until the intellect could supply a secondary cause; only then did wonder turn into knowledge. This framework allowed medieval physicians and theologians to speak of six-fingered children, healing springs, or prophetic dreams without collapsing immediately into either credulity or impiety. Medieval collectors of mirabilia—from Gervase of Tilbury’s Otia imperialia to Gerald of Wales’s Topographia Hiberniæ—located wonders at the edges of Christendom, mapping them province by province as touchstones of cognitive surprise (Knight 2001; Marzella 2017). Their catalogs, grounded in personal testimony and sworn oaths, naturalized marvels without domesticating them, embedding the appetite for the extraordinary deep inside Latin natural inquiry.

While medieval Europe grappled with the tension between universals and particulars, Song-dynasty China (960–1279) saw the emergence of yì’àn (醫案)—medical dossiers that recorded patients’ backgrounds, symptoms, and treatments (Goldschmidt 2008). Early examples, such as the Case Records of Famous Physicians (Míngyī lèi’àn), demonstrate that Chinese physicians were compiling individualized case narratives in parallel with Mediterranean traditions (Gui 2023). However, these Song-era dossiers were less formalized than the paragraph suggests; the genre matured significantly later, reaching its zenith in the problem-oriented, writer-centered yì’àn of the Ming (1368–1644) and Qing (1644–1912) dynasties (Lo and Stanley-Baker 2022).

Nevertheless, these early exemplars show that the dialectic of singularity and universality was never an exclusively European affair.

5. Marvels Reclaimed: Paradoxography and Early Modern Curiosity

The Renaissance plays a mediating role in this account, not as a simple bridge between Antiquity and modernity, but as a period in which attention to anomaly, wonder, and singularity was actively reintroduced and re-legitimized within learned medicine. Marsilio Ficino’s De vita libri tres, printed in Florence on 3 December 1489, exemplified the new centrality of marvels: part pharmacology, part astral medicine, it argued that precise, individually tailored regimens could redirect planetary influences on the fragile scholar’s body (Saif 2015). In tying a single patient’s temperament to the cosmic order, Ficino offered a model of how the extraordinary particular might revise prevailing natural philosophy (Copenhaver 1984). Renaissance collectors and naturalists did not abandon the scholastic tripartition but inverted its value hierarchy. Where the Middle Ages had tolerated the preternatural as marginal, humanists made it central. The mirabilia of nature—strange stones, monstrous births, magnetic attractions—became the preferred proofs of divine plenitude and the raw data of natural philosophy (Daston 1998b). The border between natural and preternatural blurred, while the truly supernatural (miracula) retreated into theology. In this cultural shift, the monstrum was domesticated: Aldrovandi’s Monstrorum Historia transformed prodigies once read as omens into case histories cataloged by cause, region, and anatomy. Marvels thus re-entered medicine not as moral signs but as specimens, each demanding its own causal reconstruction. Once the scholastic distinctions had framed the moral and epistemic status of wonders, early modern thinkers inverted their hierarchy.

Across the 15th and 16th centuries, curiosity about marvels migrated from conservative universities to princely courts, private studioli and the newborn learned academies (most famously the Accademia dei Lincei), where a fraternity of “preternatural philosophers”—Ficino, Pomponazzi, Cornelius Agrippa, Cardano, later della Porta—treated occult properties, monstrous births and rains of blood as legitimate data (Stolleis 2016), insisting that every spectacular particular deserved a tailored causal reconstruction (Daston 1998a). Their case-by-case method pre-figures the rhetorical logic of the medical case report: one vivid anomaly, precisely described, can redraw the outlines of theory.

The Renaissance thus saw a resurgence of interest in the particular, fueled by the rediscovery of classical texts, the rise of humanism, and expanding global horizons (Monfasani 2020). Within this cultural milieu, paradoxography—a genre that cataloged wonders, marvels, and strange occurrences—enjoyed renewed popularity (Daston 1998b). The fascination with anomalies in nature, whether in faraway lands or in one’s own backyard, dovetailed with a broader curiosity about the limits of received wisdom. In medicine, this translated into a revived interest in unique cases, not simply for their entertainment value but as potential keys to unlocking nature’s secrets.

Simultaneously, university-trained naturalists such as Conrad Gessner amassed cabinets of curiosity whose guiding principle was sheer diversity rather than classificatory neatness (Findlen 2013). Daston and Park describe these collections as practicing an “epistemology of the hunt”: particulars led only to further particulars, just as today a pilot clinical observation may seed a full cohort study (Daston 1998b). The cabinet thus stood midway between the isolated marvel and Bacon’s (1561–1626) later demand for systematic tables, echoing the uneasy coexistence of case narratives and population trials in modern biomedicine. Learned physicians followed suit. Antonio Benivieni’s (1443–1502) De abditis nonnullis ac mirandis morborum et sanationum causis (1507) assembled clinical mirabilia—vomited worms, congenital malformations, inexplicable cures—under the rubric of hidden natural causes (Jarcho 1955). For Marsilio Ficino (1433–1499) and Pietro Pomponazzi, the marvelous no longer threatened orthodoxy but invited philosophical explanation. Their writings mark the birth of the “preternatural philosopher”: the scholar who treated oddities of body and spirit as data for natural inquiry. In retrospect, Benivieni’s casebook reads like a prototype of modern medical reporting, translating the vocabulary of wonder into a method of observation (Daston 1998b).

Paradoxographical works did have their antecedents in ancient Greek texts that recounted fantastic tales of monstrous births or extraordinary events (Kazantzidis 2019), but during the Renaissance, such narratives captured the imagination of intellectuals who were increasingly willing to challenge medieval scholastic orthodoxy. Scholars like Ulisse Aldrovandi (1522–1605) compiled encyclopedic works of natural history that blended direct observation with reported anomalies (Vai and Cavazza 2006). While these figures were not clinical scientists in the modern sense, their meticulous documentation and openness to the unexpected influenced contemporary and subsequent thinking about singular cases.

In medical circles, the growing interest in anatomy—exemplified by Andreas Vesalius’s (1514–1564) groundbreaking De humani corporis fabrica—spurred a more empirical approach to the body (Vai and Cavazza 2006). As dissections became more common, so did the recognition of individual variations in anatomy and pathology. This was fertile ground for the re-emergence of the study of cases as a vehicle to highlight discoveries that might not fit neatly into prevailing theoretical frameworks. For instance, physicians writing about rare diseases or unusual surgical experiences found an audience eager for firsthand accounts of the body’s marvels.

When Ulisse Aldrovandi returned to Bologna after his 1549 heresy trial, he began assembling a museo naturale that by the early 1570s filled several rooms of the Palazzo Pubblico (Vai and Cavazza 2006). His visitors confronted shelves of two-headed lambs and jars of desiccated polyps—specimens later cataloged in the post-humous Monstrorum Historia—and the display operated as a living index of exceptions, halfway between a narrative case note and Bacon’s projected tables of instances (Aldrovandi 1983). Yet Aldrovandi pursued an almost obsessive program of measurement, illustration and cross-referencing; he aimed to catalog some 18,000 curiosities (about 7000 plants alone) and thereby surpass ancient authorities through orderly description.

The Renaissance’s embrace of paradox and marvel also aligned with an epistemological shift. While medieval Aristotelianism sought to fit anomalies into a universal framework, Renaissance scholars were increasingly comfortable with the idea that nature might harbor innumerable exceptions, each offering a clue to understanding creation’s broader design (Daston 1998b). In medicine, this meant that physicians who encountered highly unusual cases—be they miraculous cures or baffling pathologies—felt justified in publishing their observations. Such writings influenced the evolution of scientific discourse by offering a complementary counterpoint to universalizing theories: the singular, the exceptional, and the wondrous.

By the late 16th century, monstrous births had become so frequent in broadsides that Sebastian Brant (1457–1521) complained they seemed “the common course of nature” (Daston 1998b). This inflation of singularities forced naturalists—like clinicians overwhelmed by case series—to ask whether accumulating marvels required a new kind of evidence architecture, a question Bacon would dramatize in his call for a “history of nature erring” (Anstey 2012).

Thus, paradoxography in the Renaissance era can be seen as a conduit that kept the fascination with individual phenomena alive and well. It provided both a literary model and an intellectual rationale for attending to the bizarre or the inexplicable. In so doing, it planted the seeds for a more systematic scientific engagement with anomalies, which would eventually coalesce into the modern formats of case reports, and, by contrast, large-scale studies aimed at distillling universal laws.

6. The Emergence of the Scientific Method and Early Clinical Trials

The intellectual debate that flourished in Europe in the 16th and 17th centuries reshaped the rules for deciding what counts as knowledge (Goldstone 1982). Francis Bacon urged scholars to abandon reverence for inherited dogma and rebuild understanding from the ground up, brick by empirical brick (Gillespie 1979). René Descartes, trusting in mathematics to expose nature’s inner gears, pictured the world—and by extension the body—as a mechanism governed by universal laws (Ariew 2016). In this new climate, physicians began to move beyond authoritative commentary toward more deliberate forms of testing, laying intellectual foundations that would later be mobilized in the development of comparative experimental practices.

James Lind’s 1747 shipboard experiment on scurvy often stands as the iconic early example, even though it followed Bacon and Descartes by nearly a century (Sutton 2003). By splitting sick sailors into small groups and feeding each group a different remedy, Lind treated the deck of HMS Salisbury as a floating laboratory. His method captured the age’s appetite for reproducibility and side-by-side comparison, and the logic he demonstrated would ripen into the controlled designs that dominate research today (Everett 2022). It is precisely the epidemic character of scurvy—its reproducible manifestation across bodies regardless of temperament—that made such comparison epistemically plausible, marking a historical shift from strictly individualized humoral reasoning toward the treatment of illness as a shared, nameable condition, even while humoral concepts continued to structure explanation3. From the sixteenth century onward, the recurrent appearance of epidemic illnesses—plague, syphilis, and later smallpox—posed a challenge to humoral individualism. Conditions that manifested with striking regularity across bodies of different temperaments increasingly appeared to physicians as stable pathological agents rather than constitution-specific imbalances. This epidemiological visibility created, for the first time, an epistemic space in which comparison across patients was not only conceivable but necessary.

Nonetheless, the fascination with the single, revealing case persisted. Physicians continued to publish detailed narratives, both to boast of a novel cure and to alert colleagues to a puzzling failure. The newly founded Royal Society, championing “matters of fact,” encouraged its correspondents to share whatever they had observed, however odd. Early issues of Philosophical Transactions printed letters describing monstrous births, bizarre stones extracted from bladders, and sudden recoveries that seemed to defy explanation (Fontes da Costa 2002). Such anecdotes kept alive the Renaissance conviction that the extraordinary could unlock nature’s secrets. Even so, the center of gravity was shifting. Anatomists standardized dissections, pharmacologists calibrated dosages, and pathologists began to correlate lesions with symptoms, all in the hope of extracting rules that would apply across populations (Saunders 2000). The Baconian ideal of piling up observations until a pattern crystallized justified efforts to pool patient data on an unprecedented scale (Vickers 1992). In the Novum Organum (Bacon [1620] 2011), Bacon famously rejected both scholastic deduction from first principles and naïve induction by simple enumeration. His proposed method relied instead on the systematic construction of tables of presence, absence, and degrees, designed to eliminate false causes and isolate the form of a phenomenon through controlled comparison. These tables were not statistical instruments in the modern sense, nor were they intended to yield probabilistic generalizations. Rather, they functioned as epistemic filters, disciplining attention to variation and exception in order to constrain causal inference. When invoked here, Bacon’s method is not treated as a precursor of randomized trials, but as an early attempt to formalize comparison across cases without dissolving phenomena into mere averages—a concern that would later be rearticulated, under very different mathematical and institutional conditions, in clinical experimentation. Yet the habit of cherishing anomalies never quite faded: physicians understood that a single startling cure or disastrous reaction could signal an unrecognized principle or hazard (Saunders 2000).

Gradually, then, the epistemic value of singular cases changed. Instead of ending the discussion, a striking vignette more often served as a prolog, prompting calls for broader investigation. Wonders became hypotheses; anecdotes became pilot data. The Renaissance delight in marvels blended with the revolutionary hunger for universal explanation, and medicine learned to thrive on both. Out of that uneasy partnership emerged a research culture willing to balance the disciplined choreography of large trials with a continuing readiness to listen when one unexpected story demands to be heard.

7. Modern Consolidation: Case Reports and Clinical Trials in the 19th and 20th Centuries

By the 19th century, medicine was increasingly supported by a robust institutional framework: hospitals, laboratories, and professional societies all contributed to the shaping of how clinical knowledge was gathered and disseminated (Rosenberg 1977). The growth of epidemiology, exemplified by John Snow’s (1813–1858) work on cholera, showcased the power of systematic observation and population-level studies (Cameron and Jones 1983). Epidemic diseases intensified this epistemic tension by producing repeated, comparable singular cases that demanded comparison, without eliminating the diagnostic primacy of individual cases. Around the same time, physiological experiments by figures like Claude Bernard (1813–1878) underscored the importance of controlled laboratory research (Noble 2008). Out of this milieu arose a clearer demarcation between anecdotal observations and structured, statistically grounded investigations (Normandin 2007). Pierre Charles-Alexandre Louis’s (1787–1872) numerical method in Paris hospitals, drawing on Laplacian probability theory, quantified outcomes from hundreds of phlebotomized pneumonia patients (Brabin 2021); his demonstration that blood-letting increased mortality crystallized the moral stakes of aggregation and set the stage for Bradford Hill’s randomization in the 20th century (Cox 2018).

These developments unfolded against the backdrop of an earlier transformation in eighteenth-century medical classification, particularly within the French tradition of nosology and physiological medicine. Building on Enlightenment classificatory projects exemplified by Linnaean taxonomy, physicians such as Boissier de Sauvages (1706–1767) and later Philippe Pinel (1745–1826) sought to organize diseases into stable, nameable entities based on shared symptoms and courses (Hess and Mendelsohn 2014). This nosological reconfiguration was reinforced by the rise of anatomical and physiological localization, most notably in the work of Xavier Bichat (1771–1802), which reframed disease as a lesion-based process rather than a constitution-specific imbalance (Foucault 2012). As historians of medicine have emphasized, this convergence of classification, anatomy, and clinical observation—crystallizing in the Paris clinical school—rendered diseases amenable to collective comparison, numerical analysis, and standardized therapeutic evaluation, thereby creating the epistemic conditions for nineteenth-century statistical medicine and, ultimately, clinical trials.

This transformation has been analyzed in detail by Ian Hacking and Lorraine Daston, who have shown how the emergence of probability and statistical reasoning in the eighteenth and nineteenth centuries reshaped not only scientific methods but also the epistemic virtues governing judgment, comparison, and generalization. Hacking traced how probabilistic thinking reconfigured the conditions under which phenomena could be treated as regular, comparable, and governable (Hacking 1990, 2006), while Daston emphasized how Enlightenment probability articulated new norms of rational decision-making and objectivity (Daston 2021). From this perspective, numerical aggregation does not merely supplement clinical observation but redefines the epistemic space in which singular cases acquire meaning, legitimacy, and moral weight. Louis’s numerical method thus represents not the origin of generalization in medicine, but a historically specific formalization of a much older problem: how to move from individual experience to collective judgment without erasing the singular.

In the late 19th and early 20th centuries, advances in microbiology, pathology, and pharmacology made the case for collective data even stronger (Worboys 2007). The drive to standardize medical practices—spurred by professional organizations, licensing bodies, and burgeoning scientific journals—naturally favored replicable experiments over singular accounts (Lachmund 1998). Yet, case reports persisted as a vital literary form. They were especially significant in areas where new phenomena were being observed: for instance, in early psychology and psychiatry, where Sigmund Freud’s (1856–1939) case studies became foundational texts, illustrating the complexities of the mind before standardized psychometric tools were widely available (Sealey 2011).

In mainstream biomedical fields, case reports retained their value in identifying emergent diseases, rare complications, or novel treatment effects. Physicians recognized that while controlled trials could confirm efficacy and safety on a population level, the first indication of a new syndrome or atypical drug interaction often appeared in an individual patient. Journals began to organize their publications accordingly, usually with research articles backed by statistical data at the forefront, but still allowing space for shorter, focused case reports. By the mid-20th century, this dual system had solidified, mirroring the broader cultural shift toward “evidence-based medicine,” a framework that prized RCTs as the gold standard but also acknowledged the heuristic value of singular anecdotes (Cartabellotta et al. 1998).

Crucially, the tension between universalization and particularization was institutionalized, rather than resolved. On one hand, RCTs expanded in size, complexity, and regulatory importance, especially after landmark studies in cardiology and oncology demonstrated the need for large patient cohorts to discern true effects (Thiers et al. 2008). On the other hand, case reports continued to serve as the early warning system of clinical practice, flagging unexpected results and steering medical thought toward new questions and new experiments (Albrecht et al. 2009). Thus, the 19th and 20th centuries can be seen as a period of consolidation, where the historical dialectic found a modern equilibrium, though not without ongoing debates about the relative weight of anecdotal versus statistical evidence.

8. Data Deluge and the N-of-1: Precision Medicine’s Dual Heritage

Big-data analytics now set the tempo of biomedical discovery (Ivanova 2024). Meta-analyses pooling dozens of randomized trials, exhaustive systematic reviews, and population-scale genomic screens dominate leading journals, pushing statistics to center stage (Batko and Ślęzak 2022; Hassan et al. 2022). Clinicians and policymakers lean on living guidelines that distil thousands of observations into concise practice statements (Schünemann 2022). This enterprise advances a conviction articulated in different forms within Aristotelian natural philosophy and Baconian experimental reform: that systematic inquiry can yield stable, generalizable knowledge, now supported by global consortia, cloud infrastructure and algorithms able to sift petabytes of data overnight, turning variation into averages and averages into policy (Anjum et al. 2017). Statistical reasoning did not replace case-based reasoning but formalized one powerful but historically contingent strategy for managing its limits.

Yet a single patient has not disappeared beneath this avalanche. The same infrastructure that feeds mega-studies—electronic records, online registries and machine-learning signal detectors—also captures the rare and the unforeseen (Lewis et al. 2024). When an unusual genomic variant surfaces in one person, clinicians can summon collaborators on another continent within days, blending Hippocratic curiosity with high-tech reach (Watson 2022). Precision medicine, intent on tailoring therapy to each molecular fingerprint, treats such idiosyncratic data as opportunity rather than noise (Sisodiya 2021). As technology enables increasingly granular patient profiles, the concept of an n-of-1 trial, in which a single patient undergoes different treatment regimens in a controlled sequence, gains legitimacy (Nikanjam et al. 2025).

That duality often lands on the desks of ethics boards and regulators. Guideline developers bound to multicenter trials can clash with oncologists treating tumors whose mutations excluded them from those studies (Khan et al. 2025). A dramatic remission achieved with an off-label drug and recorded in a case report forces a dilemma: extend the therapy quickly or wait for phase-III proof (Jeyaraman et al. 2025). In moments like these, the Hippocratic duty to do no harm meets the scientific demand for rigor, reminding us that collective evidence and individual welfare share a fragile, negotiated border (Atkinson et al. 2020).

In the publishing world, the open access movement has also facilitated the circulation of case reports (Tennant et al. 2016). Editorial policies vary widely and many high-impact journals have reduced or eliminated dedicated case report sections, often due to concerns about citation metrics rather than scientific relevance (Nissen and Wynn 2012). Nevertheless some journals maintain sections specifically devoted to case studies, which may still constitute a non-negligible proportion of the total number of published articles in general medicine (Gopikrishna 2010). Together with platforms for preprints and post-publication peer review, these venues enable the dissemination of singular clinical insights beyond traditional editorial constraints (Smart 2022; da Silva 2015; Danish et al. 2017). In this distributed ecosystem a digital ripple from one bedside can become a global conversation overnight, allowing vigilance, imagination and collective problem-solving to run alongside statistical certainty (Dananjayan and Raj 2021).

What emerges, then, is not a contest of opposites but a braided rope. Meta-analyses, living reviews and algorithm-driven guidelines pull medicine toward broadly applicable norms, while precision therapeutics and digital storytelling draw it back to the irreducible particular. Their sustained interplay keeps the discipline alert to patterns that hold for the many and to signals that flash from the few. Even in an era saturated with data, progress can still pivot on a single well-documented experience, reminding us that universals survive only by listening closely to anomalies, which is a balance likely to deepen as new technologies stitch personal narratives to global datasets (Finlayson et al. 2014). Contemporary biomedicine does not represent a return to Hippocratic medicine, nor a revival of premodern epistemologies. Rather, developments such as precision medicine, genomic stratification, and n-of-1 trial designs rearticulate—under technologically saturated conditions—the same epistemic problem already visible in ancient case narratives: how to reconcile the irreducible individuality of biological phenomena with the demand for generalizable knowledge.

9. Past as Prolog: Balancing Marvels and Metrics Today

Medicine has never been content to resolve the tension between the individual and the collective. Across historical periods marked by radically different ontologies and methods, medical reasoning has repeatedly oscillated between attention to singular patients and the search for patterns that extend across populations. That dual orientation—remaining alert to what is anomalous while striving to establish what is broadly reliable—has structured medical knowledge for more than two millennia. What appears innovative in contemporary biomedical research often lies less in the epistemic problem itself than in the technical means deployed to manage it.

Randomized controlled trials, the modern heirs of concerns already articulated in Aristotelian and Baconian traditions, give us the most reliable answers we have about average benefits and harms. Yet the humble case report, descended from Hippocratic narratives and Renaissance catalogs of marvels, still reminds us that biology loves exceptions. A single unexpected outcome can expose a blind spot in prevailing theory, inspire a fresh hypothesis, or even shift the standard of care, breaking the current paradigms (Kuhn 1970).

Current challenges underscore why we still need both lenses. Pandemic pathogens, ultra-rare genetic conditions and precision medicine therapies each demand vast datasets to see the signal, yet they often announce themselves in a solitary, puzzling case. Large trials tell us how most people will respond; outliers tell us why some will not, and where the next breakthrough may lie.

Seen in this light, the presence of both case reports and clinical trials in today’s journals is not a leftover from an untidy past but a working illustration of how knowledge actually grows. By keeping marvels and metrics in conversation, we respect the full complexity of human health, honoring the person in front of us while refining principles that can guide care for all. History, then, is not an ornament to modern practice; it is a caution and a compass, reminding us that progress depends on balancing the universal with the particular, and on listening closely when one lone story contradicts the prevailing chorus.