WILLIAM OF CHAMPEAUX. - Philosopher, born c. 1070, died as bishop of Châlons-sur-Marne in 1121. His teachers were Manegold of Lautenbach in Paris, then Anselm of Laon, and finally Roscellin at Compiègne. He taught first at the cathedral school in Paris and later at Saint-Victor.
Through Roscellin, William of Champeaux came into contact with the problem of universals. Roscellin was a nominalist; of him, John of Salisbury writes in the *Polycratius*, VII, 12 (ed. C. I. Webb, II, p. 142): «There were those who said that the very words [universals] were genera and species, but their opinion has been refuted and has almost vanished along with its author.» Nominalism led Roscellin to conceive the Holy Trinity as three gods. William opposed this with his realism and found himself compelled to reconcile his philosophical theory with the mystery of the Trinity, as appears in a significant passage from his *Sentences*:
> «You see how these two words, "one" and "the same," are taken in two ways: according to indifference and according to identity of the same essence. According to indifference, we say that Peter and Paul are the same inasmuch as they are men: for as far as their humanity is concerned, one is rational and the other is rational, one is mortal and the other is mortal. But if we wish to speak the truth, their humanity is not the same but similar, since they are men. However, this mode of unity cannot be applied to the nature of divinity» (*Guillelmi Campellensis Sententiae vel Quaestiones* XLVII, in G. Lefèvre, *Les variations de G. et de la question des universaux*, Lille 1898, pp. 14 and 25).
In this text, two phases of William’s thought—or rather of the expression of his thought—are touched upon. The first phase, that of essential identity, was abandoned by William under the pressure of his pupil Abelard, who claimed to see in it a profession of pantheism:
> «He (William of Champeaux) held the view concerning the community of universals that he constructed the whole thing in such a way that the same essence inheres simultaneously in each individual, none of which has any essential diversity but only a variety of accidents» (*Historia calamitatum*, cap. 2: PL 178, 119).
The final words of the cited passage make clear that William’s realism originated from Boethius’s words in *De Trinitate*: «It is the variety of accidents that makes the difference in number,» and could merit the accusation of reducing individuation to accidents. By placing essence extrinsically individuated in reality (and in the first as well as the second manner), it excluded any profession of pantheism. Precisely to remove this misunderstanding regarding pantheism, William spoke in the second manner of essential indifference rather than essential identity, with the aforementioned caveat regarding the one and triune God: where, by conceiving the divine essence almost as a universal of the three divine persons, one must be careful not to think of it as multiplied in them. Here we are in identity, not merely in indifference.
The second phase of William’s thought developed at Saint-Victor. Of this school and its mystical character, William of Champeaux may be considered an initiate.
Principal works, besides the already cited *Sentences*: *De Sacramento altaris* (fragments in PL 163, 1039–40); *De origine animae* (doubtful; fragments, ibid. 1043–44); *Dialogus seu altercatio cuiusdam christiani et iudaei de fide catholica* (ibid. 1046–72); *De essentia et substantia Dei et de tribus eius personis* (fragments in V. Cousin, *Fragments philosophiques*, II, Paris 1865, pp. 328–35).