Anselm of Canterbury
1033 CE – 1109 CE · Medieval Era
“God is that than which nothing greater can be conceived: and must therefore exist.”
Biography
Anselm was a Benedictine monk who became Archbishop of Canterbury and an original thinker of the medieval period. Born in Aosta in northern Italy, he entered the monastery of Bec in Normandy, where he rose to become prior and then abbot. His philosophical works, written in the form of meditations and dialogues, combined rigorous logical argument with deep personal piety. His insistence that faith and reason are complementary, his motto was fides quaerens intellectum, 'faith seeking understanding.'
Major Works
Key Arguments
Click “Philosophy 101” to read the full exploration of each argument.
The Ontological Argument
In the Proslogion, Anselm offered an argument that has never stopped generating debate. God, he argued, is 'that than which nothing greater can be conceived.' Now, something that exists in reality is greater than something that exists only in the mind. Therefore, if God exists only in the mind, we can conceive of something greater, namely, a God that exists in reality. But this contradicts the definition of God as the greatest conceivable being. Therefore, God must exist in reality, not simply in the mind. The argument derives God's existence from the very concept of God, using pure reason alone, no appeal to scripture, experience, or authority.
Why it matters: Endlessly debated in philosophy of religion. It has been rejected by Aquinas, demolished by Kant (who argued that existence is not a predicate), revived by Gödel and Plantinga in modal logic, and continues to generate new scholarship. Whether one finds it convincing or not, its sheer ingenuity and its attempt to prove God's existence through reason alone make it a permanent fixture of Western philosophy.
Faith Seeking Understanding
Anselm insisted that faith comes first, one must believe before one can understand. But faith is not the end of the intellectual journey; it is the beginning. Once you believe, you are obligated to use your reason to understand what you believe as deeply as possible. To refuse to seek rational understanding of your faith is a form of intellectual negligence. This position threads a needle between two extremes: pure fideism (faith needs no reason) and pure rationalism (reason replaces faith).
Why it matters: Established the intellectual program of Scholasticism for three centuries. Anselm's formula, believe in order to understand, defined the relationship between faith and reason for the entire medieval university tradition and continues to influence theologians who see philosophy as a tool for deepening, not replacing, religious commitment.
Cur Deus Homo: Why God Became Man
In Cur Deus Homo, Anselm asked why God had to become incarnate in Christ to save humanity. His answer was a theory of satisfaction: human sin is an offense against God's infinite honor, and because God is infinite, the offense requires an infinite satisfaction that no finite human being can provide. Only a being who is both fully human (to represent humanity) and fully divine (to offer infinite satisfaction) can bridge the gap. The Incarnation was therefore not arbitrary but logically necessary.
Why it matters: The dominant theory of atonement in Western Christianity. It replaced the older 'ransom' theory and shaped Catholic and Protestant theology for centuries. Philosophically, it is a remarkable example of applying rigorous logical analysis to theological questions, treating the Incarnation as the solution to a problem that can be stated in precise, almost mathematical terms.
Lasting Influence
Established the scholastic method of reasoning from faith. His ontological argument has been debated for nearly a thousand years.
Your Reading Path
The Companion Guide
Seven eras of philosophy in one volume — reading lists, key terms, journal prompts · $19.99