Warranted Christian Belief

This monograph represents Plantinga's culminating work in reformed epistemology, developing a sophisticated model for how Christian belief can possess warrant—that property which transforms true belief into knowledge. Building upon his earlier critiques of classical foundationalism and evidentialist challenges to religious belief, Plantinga constructs what he calls the "Aquinas/Calvin" or "A/C" model, which proposes that humans possess a natural cognitive faculty, the sensus divinitatis, that produces belief in God in appropriate circumstances.

The work's central innovation lies in its externalist approach to religious epistemology. Rather than attempting to meet internalist demands for evidence or argumentation, Plantinga argues that Christian beliefs can be properly basic—warranted without being based on other beliefs or evidence. On his model, if Christianity is true, then very likely Christian beliefs formed through the internal instigation of the Holy Spirit are warranted. This creates what Plantinga calls the "de jure/de facto" connection: objections to the rationality or warrant of Christian belief ultimately depend on the truth or falsity of Christianity itself.

Plantinga engages extensively with historical and contemporary critics of religious belief, including Freud, Marx, Kant, and recent evidentialist philosophers. He argues that their objections typically assume the falsity of theism and thus cannot serve as independent reasons to reject the warrant of Christian belief. The work also addresses the problem of religious diversity and develops extended responses to various defeaters, including evolutionary arguments against the reliability of our cognitive faculties and the problem of evil.

The monograph's significance extends beyond religious epistemology to general epistemological theory. Plantinga's proper functionalism—the view that warrant derives from properly functioning cognitive faculties operating in appropriate environments according to a design plan aimed at truth—offers a comprehensive alternative to internalist theories of knowledge. His treatment of testimony, memory, and perception as sources of warranted belief provides a framework for understanding how religious experience might similarly generate warranted beliefs.

This work consolidates decades of Plantinga's contributions to philosophy of religion, offering Christian philosophers resources for defending the rational acceptability of their beliefs while challenging the epistemological assumptions underlying much modern religious skepticism. Its influence extends across analytic philosophy of religion, epistemology, and theological discussions of faith and reason.