The cumulative case argument from religious experience contends that while individual religious experiences may not constitute decisive evidence for God's existence, the aggregate weight of diverse religious experiences across cultures, times, and traditions provides significant evidential support for theistic belief. This argument employs an abductive or inference-to-the-best-explanation structure, proposing that the hypothesis of God's existence offers the most comprehensive explanation for the widespread occurrence, phenomenological consistency, and transformative effects of religious experiences. Unlike arguments that focus on specific types of religious experience, this formulation emphasizes the epistemic significance of the sheer quantity, diversity, and cross-cultural convergence of reported encounters with the divine.
The cumulative case approach to religious experience gained prominence through Richard Swinburne's "The Existence of God" (1979, revised 2004), where he argues that the principle of credulity and testimony apply to religious experiences collectively. Caroline Franks Davis developed this approach in "The Evidential Force of Religious Experience" (1989), systematically cataloging types of religious experiences and their cumulative evidential value. William Alston's "Perceiving God" (1991) provided sophisticated epistemological foundations, arguing that Christian mystical practice forms a socially established doxastic practice comparable to sense perception. More recently, Kai-Man Kwan's "The Rainbow of Experiences, Critical Trust, and God" (2011) has advanced a critical trust approach that acknowledges both the diversity and commonalities in religious experiences across traditions.
The strongest objections to the cumulative case argument center on the problem of religious diversity and naturalistic explanations. Critics like J.L. Mackie in "The Miracle of Theism" (1982) argue that conflicting religious experiences across traditions undermine rather than support any particular theistic claim. Matthew Ratcliffe and other cognitive scientists propose that religious experiences can be fully explained through neurological and psychological mechanisms without invoking supernatural causes. Defenders respond that diversity in religious experience no more undermines their veridicality than perceptual diversity undermines sense perception. Swinburne and others maintain that while naturalistic factors may be necessary conditions for religious experience, they need not be sufficient explanations, and the theistic hypothesis better accounts for the specific phenomenological features and transformative effects of these experiences.
The cumulative case argument differs from other formulations in the religious experience family by its methodological approach rather than its focus on particular experiential types. Unlike the mystical experience argument, which emphasizes extraordinary unitive states, or the numinous experience argument, which focuses on encounters with the holy, the cumulative case considers all types of religious experience as potentially evidential. It differs from the sensus divinitatis approach by not positing a specific cognitive faculty for perceiving God, and from conversion experience arguments by including gradual as well as sudden religious experiences. Most distinctively, while other formulations might treat individual experiences as potentially sufficient evidence, the cumulative case argument explicitly requires aggregation across multiple experiences and experiencers to build its evidential case.