Abstract
<jats:title>Abstract</jats:title> <jats:p>Individuals who start propagating a conspiracy theory often move on to quickly propagate additional ones. We propose that falling into an online rabbit hole of conspiracy theories is a semantic cascade comprising four processes: inadvertent entry, descent via the adoption of new conspiracy theories, acceleration, and diversification. Analysis of the COVID-19 crisis shows that individuals enter the rabbit hole through gateway theories—plausible and easy to believe explanations. Descent occurs as users shift between semantically proximal conspiracy theories in response to rising threat. The adoption of new conspiracy theories accelerates as the number of previously endorsed conspiracy theories increases and the time since last new adoption decreases. While descent is triggered by a single crisis, diversification occurs when individuals who have entered a rabbit hole formulate new, semantically distant conspiracy theories to explain new crises as they occur, as happened when the Black Lives Matter (BLM) protests started. This pattern of results is consistent with punctuated equilibrium model of incremental change through a semantic proximity-directed descent and disruptive change comprising semantic distant theories.</jats:p>