Christian philosopher Alvin Plantinga turns 93 on Saturday, November 15. He is the first long-time university professor to be part of CT’s new series, Long Obedience in the Same Direction, which started one month ago with happy birthday wishes to Joni Eareckson Tada.

Plantinga has been called “America’s leading orthodox Protestant philosopher of God,” “arguably the greatest philosopher of the last century,” and simply “God’s philosopher.” He is one of the of the most-cited contemporary philosophers in the Stanford Encyclopedia of Philosophy and is widely credited with a renaissance of Christian philosophy and the revitalization of the philosophy of religion. 

“In the 1950s there was not a single published defense of religious belief by a prominent philosopher,” said philosopher Kelly James Clark, one of Plantinga’s students. “By the 1990s there were literally hundreds of books and articles, from Yale to UCLA and from Oxford to Heidelberg, defending and developing the spiritual dimension. The difference between 1950 and 1990 is, quite simply, Alvin Plantinga.”

The philosopher made major contributions to the field of epistemology—the study of knowledge and the justification of knowledge. He deployed modal logic and meticulous, analytic arguments to attack logical positivism and classical foundationalism, making the case there were flaws in their standards of rationality. 

“The field was transformed,” fellow philosopher and longtime friend Nicholas Wolterstorff said in 2011. “Once the positivist strictures about talking about God were removed, philosophical theology flourished as it has not since the middle ages. … For philosophy of religion and the central disciplines of epistemology and metaphysics, his fingerprints are indeed everywhere.”

Starting with his book God and Other Minds and continuing with more than a dozen other titles, including The Nature of Necessity, Essays in the Metaphysics of Modality, Warrant and Proper Function, and Warranted Christian Belief, Plantinga argued that theistic belief is reasonable, rational, and sensible. He went so far as to make the case that it was rational to believe without evidence or a good argument—or any argument. 

Belief in God, according to Plantinga, was “properly basic.”

“There certainly are arguments for the existence of God—the so-called theistic proofs; but I don’t really need them,” Plantinga said. “People who believe in God but don’t believe on the basis of arguments—and that would certainly be most of us who believe in God—are perfectly sensible and perfectly OK from an intellectual view. … That’s what I’ve spent most of my life arguing. It may be a small point, but I think it’s important.”

Plantinga was born in Ann Arbor, Michigan, in 1932. His parents, Lettie (Bossenbroek) and Cornelius Plantinga, were committed members of the Christian Reformed Church, part of the Dutch Calvinist tradition. 

Plantinga later said that he never remembered a time he wasn’t Christian. In some of his earliest memories, he was sitting in church, sweltering, and listening to a sermon he didn’t understand (because it was in Dutch) mix with the sound of the summer cicadas. Plantinga did not go through a transformative conversion experience or have any kind of epiphany about God, though he could point to several occasions when he felt a divine presence.

He started taking his faith seriously for himself when he was 8 or 9 and engaging in theological debates at 11 or 12—predestination, double predestination, divine foreknowledge, and free will were all popular topics.   

Plantinga considered becoming a pastor but didn’t feel especially drawn to the ministry. “I probably wouldn’t have been a very good pastor,” he later said. “I probably would have bored people talking about philosophy.” 

The family moved to South Dakota for a teaching job and then North Dakota, where Cornelius Plantinga instructed students in Latin, Greek, philosophy, and psychology at Jamestown College, halfway between Fargo and Bismarck.

Jamestown was a spot on the prairie known as the birthplace of Western novelist Louis L’Amour and would come to be home of the world’s largest buffalo statue. But Plantinga loved it. 

“I remember with delight and a sort of longing, the haunting, supernal beauty of the prairie on a June morning just after sunrise—the marvellous liquid song of the meadow lark, the golden sunlight, the air cool and delicious and laden with the fragrance of a thousand wildflowers,” he wrote. “I left regretfully.”

He left in 1950 at the age of 17, when his father got a job teaching in the psychology department at Calvin College in Grand Rapids, Michigan. Plantinga didn’t stay long. He got a scholarship to attend Harvard and enrolled that fall.

Visiting his family over spring break, Plantinga happened to sit in on William Harry Jellema’s philosophy class. He was riveted. 

“Jellema lectured in magisterial style, with the entire history of Western philosophy obviously at his fingertips,” Plantinga later wrote. “He seemed to display astonishing and profound insights into the inner dynamics of modern philosophy. … I came deeply under his spell; had he told me black was white I would have had a genuine intellectual struggle.”

Plantinga returned to Grand Rapids and enrolled at Calvin to study with Jellema. After graduating he went on to graduate school at the University of Michigan. He was unhappy with the analytic philosophy then in vogue—the thinking seemed so small and incapable of saying anything interesting about the world—but he did develop an interest in arguments over the standards of rationality and what counts as a rational belief.

“I conceived a particular dislike for the dreaded Verifiability Criterion of Meaning,” he later said. “I could never see the slightest reason for accepting it.”

Plantinga carried that idea with him through his doctoral studies at Yale University and into his first teaching position at Wayne State University, then a major center for analytic philosophy in Detroit. There, in rigorous debates that lasted days and even weeks, he started using modal logic to recover—and sharpen—medieval scholasticism. 

“A working knowledge of these modal matters is absolutely essential to clear thinking on most philosophical topics; nearly all philosophical topics, if pushed far enough, wind up crucially involving matters of modality,” he later wrote. “The same goes for theology. … It is essential for decent work on many of the main topics of theology.”

Plantinga started working on the problem of the rationality of belief. Critics of Christianity said evidence for belief in God is insufficient and the argument that God is self-evident is circular. 

Plantinga considered arguments for the existence of God—cosmological, ontological, and teleological—and judged each unsuccessful. Then he looked at the arguments against the existence of God, including the problem of evil, the paradox of omnipotence, and verificationism, and concluded that “none of these survives close scrutiny.” 

The young philosopher then developed his own argument, borrowing and adapting the solution to what is known as “the problem of other minds.” 

People cannot possibly be wrong about their own existence, as René Descartes demonstrated with his famous declaration, “I think therefore I am,” but one could easily be mistaken about another’s consciousness. We don’t have access to other minds. We can’t know minds inductively or deductively—but we can extrapolate and analogize and conclude that people are not cleverly designed robots but have thoughts, feelings, and experiences as vibrant and real as our own.

“I conclude,” Plantinga wrote in 1967, “that belief in other minds and belief in God are in the same epistemological boat. … But obviously the former is rational; so, therefore, is the latter.” 

The argument was innovative, bold, and transformative. But Plantinga decided he hadn’t gone far enough. He had accepted that idea that beliefs were only rational if they were based on arguments. But most people don’t develop propositions about other minds. They just assume—and that is rational, Plantinga thought.

Similarly, someone might remember eating breakfast, but if pressed, that person couldn’t provide evidence of corn flakes. Nor could the person argue the past breakfast was self-evident or necessarily true. And yet it wouldn’t be unreasonable to believe in breakfast anyway. 

Some beliefs, Plantinga concluded, don’t need evidence or arguments. 

“Beliefs of this sort are typically and properly taken as basic,” he argued. “It would be a mistake to describe them as groundless.”

Plantinga said that of course there were arguments for God’s existence—he even compiled a list of two dozen that he found compelling—but they weren’t actually necessary. 

“One doesn’t need arguments for justified and rational Christian belief,” he wrote. “Theistic belief … can have warrant sufficient for knowledge for someone, even if he or she doesn’t believe on the basis of theistic arguments, and even if in fact no good theistic arguments exist.”

Plantinga continued to develop that argument in articles and books, including the trilogy Warrant: The Current Debate, Warrant and Proper Function, and Warranted Christian Belief. He also tackled a range of other subjects, including the problem of evil, the nature of necessity, the nature of God, and the relationship between religion and science. 

Plantinga taught at Calvin College, where he replaced Jellema in the philosophy department, from 1963 to 1982. He taught at the University of Notre Dame from 1982 until his retirement in 2010. 

Notre Dame named a fellowship after Plantinga. Baylor University named an award for him. He received the Templeton Prize worth $1.4 million in 2017. 

“His influence cuts across faiths. It cuts across generations,” philosopher Meghan Sullivan said when Plantinga received the award. “Professor Plantinga, your work in epistemology, metaphysics and religion emboldened many philosophers to wonder again.”

Plantinga noted that he hadn’t converted a lot of philosophers to Christian faith, nor was Christianity the predominant view at the end of his career. But he was satisfied with what he had accomplished. 

“What I’ve always wanted to do as a philosopher is defend Christianity—defend a Christian way of thinking about things and argue that to be a Christian is not to be irrational or senseless or silly,” he told Christianity Today. “You can reasonably be a Christian.”