Roscelin of Compiègne (c. 1050 - c. 1125) was a French scholastic philosopher and theologian, best known as an early and controversial proponent of nominalism - the position that universal concepts are mere names or vocal utterances (voces) rather than real entities existing independently of individual things. He is considered a formative figure in the scholastic tradition, particularly in the long dispute over the problem of universals that defined much of medieval philosophy.

Roscelin was born in Compiègne and received his education at Soissons and Reims. He taught at Compiègne and later at other cathedral schools in France and England. His most notable student was Peter Abelard, who engaged with and ultimately criticized Roscelin's positions. Almost none of Roscelin's own writings survive; knowledge of his views derives largely from hostile sources, chiefly the polemical letters of Anselm of Canterbury and scattered references in Abelard's works.

The central philosophical question Roscelin engaged was the problem of universals: whether abstract categories such as “humanity,” “redness,” or “animality” have any real existence, or whether they are simply names applied to collections of individual things. Roscelin's position - that universals are nothing more than voces (vocal sounds) or nomina (names) - placed him at one extreme of the debate, in direct opposition to realist positions holding that universals exist as genuine entities in some form.

Roscelin's nominalism brought him into sharp conflict with orthodox Trinitarian theology. If universals lack real existence, critics argued, the unity of the three Persons of the Trinity could not be maintained - implying either three separate divine substances (tritheism) or that two of the Persons were subordinate to the Father. Anselm accused Roscelin of tritheism on this basis. Roscelin was condemned at the Council of Soissons in 1092 and compelled to recant, though he later disputed the characterization of his views. He subsequently moved between France and England, continuing to teach and engage in polemical exchanges, including a controversy with Abelard over Christology.

Because Roscelin's own writings are lost, his precise doctrines are difficult to reconstruct with confidence, and scholarly assessments of his actual positions vary. He is nonetheless treated as a pivotal figure in the history of medieval philosophy, representing the earliest clearly attested formulation of nominalist thought in the Latin West. The debate he helped initiate over universals continued through Abelard, William of Ockham, and beyond, and is regarded as one of the defining intellectual controversies of the medieval period.

• Roscelin as Radical Nominalist-viewpoint - The view that Roscelin held that universals are nothing beyond spoken words, with no mental or real correlate.
• Roscelin as Moderate Nominalist-viewpoint - The view that Roscelin's position was more nuanced than his critics reported, and should not be equated with later, more developed forms of nominalism.
• Roscelin and Tritheism-viewpoint - The view, advanced by Anselm and others, that his nominalism entailed a tritheist conception of the Trinity.

• Roscelin - History
• Nominalism
• Problem of Universals
• Scholasticism
• Peter Abelard
• Anselm of Canterbury
• Medieval Philosophy - Metaphysics Consensus

1. Roscelin's dates are approximate. Primary sources give no precise birth or death year.
2. The principal source for Roscelin's views is Anselm of Canterbury, Epistola de incarnatione Verbi (c. 1094), a polemical text. Abelard's Historia Calamitatum and logical works provide additional, also hostile, testimony.
3. The Council of Soissons (1092) condemned Roscelin's Trinitarian teaching; the condemnation is documented in Anselm's correspondence.
4. J. Reiners, Der Nominalismus in der Frühscholastik (Münster: Aschendorff, 1910), remains a foundational modern study, though subsequent scholarship has revised aspects of his reconstruction.
5. For a general overview of the universals debate in its medieval context, see Problem of Universals - History.