Did pope gregory the IX contribute to the bubonic plague?
Executive summary
The short answer: there is no reliable evidence that Pope Gregory IX intentionally caused—or can be held meaningfully responsible for—the bubonic plague; the story that his 1233 decretal "Vox in Rama" ordered mass extermination of cats which then allowed rats to spread the Black Death is a modern myth built from loose inferences and chronologic leaps [1] [2]. Careful reading of the sources shows Gregory did condemn certain heretical rites and associated some animals with diabolism, but neither the papal text nor contemporaneous records support a continent‑wide cat pogrom that produced the plague a century later [3] [4].
1. What Gregory actually did: a decretal against a heresy, not a cat massacre
Primary summaries of Gregory IX’s actions record that he issued documents—collectively the Decretals—and specifically a decretal called Vox in Rama in the early 1230s that condemned a form of Luciferian heresy and described diabolic imagery that included frogs, toads and a demonic black cat figure; modern retellings have simplified that symbolic condemnation into an alleged “order to exterminate black cats,” but that interpretation is not supported by careful reading of the decretal or by mainstream scholarship cited in these popular debunks [1] [3] [4].
2. The chronology problem: more than a century separates decree and pandemic
The Black Death ravaged Europe beginning around 1346–1347; Vox in Rama was issued circa 1232–1234—more than 110 years earlier—so the causal chain required by the popular myth (pope orders cat killings → cats disappear → rats proliferate → plague spreads) collapses under basic chronology unless one supplies a massive, undocumented campaign of extermination that persisted across generations and geographies, a claim for which the consulted reporting finds no firm evidence [2] [4].
3. Geographic and cultural limits undercut the “papal domino” theory
Even if Vox in Rama stigmatized certain animals in parts of Christendom, papal decretals did not instantly or uniformly dictate daily animal husbandry practices across Africa and Asia, where the plague also struck hard; critics note that regions such as Egypt and parts of Asia—places with strong cat traditions—were affected by the pandemic, undermining any neat narrative that European cat deaths alone explain the disease’s global pattern [2] [4].
4. The evidentiary problem: myth, amplification and modern clickbait
Many of the sources collected here are modern retellings that amplify a memorable image (the pope who hated black cats) into a moralized origin story for the Black Death; several skeptical accounts explicitly call the mass‑extermination narrative “pure fantasy” or point to holes in the logic and sourcing, and even Wikipedia’s talk page records that the link is a popular myth rather than a settled historical fact [5] [2] [6]. At the same time, a minority of opinion pieces and popular histories repeat the claim without demonstrating contemporaneous demographic data on cat populations or documentary proof of organized campaigns to kill cats across medieval Europe [7] [8].
5. Balanced conclusion: blame the bacteria, not the bull
Historical responsibility for the Black Death rests with Yersinia pestis and the epidemiological vectors and trade networks of the 14th century rather than with a single 13th‑century decretal; while Gregory IX’s Vox in Rama contributed to medieval demonization of certain animals and likely encouraged local persecutions of alleged witches and their supposed familiars in places, there is no documented, direct causal chain showing that his words produced a cat die‑off sufficient to enable the pandemic a century later [3] [4] [2]. The myth persists because it is a tidy narrative—blame a visible institution for a vast catastrophe—but responsible history requires caution: the sources assembled here show correlation in theme (anti‑cat rhetoric) but not the documentary or epidemiological proof that would be necessary to say Gregory IX “contributed to” the bubonic plague in any material, causal sense [1] [2] [5].