On his return to Paris, some years later, he found that William had founded a house of Augustinian Canons at the Abbey of St Victor. He returned to William to hear his lectures on rhetoric, and again clashed with him over his theory of universals. He had maintained, says Abelard, that in the common existence of universals, the whole species was essentially the same in each of its individuals, and among these there was no essential difference, but only variety due to multiplicity of accidents. This is realism, the belief that universals signify something real, as opposed to nominalism, the belief that they are merely nouns, names, words. Either position if pushed to its logical conclusion produces difficulties, even absurdities.
Realism tends towards collectivism, nominalism to individualism.
He then returned to Brittany at the request of his mother Lucie. His duty performed, Abelard returned to France, with the special purpose, as he tells us, of studying theology. We do not know what brought about this change of direction in Abelard's intellectual life. It may be merely coincidental that it followed on immediately from his spending time with his mother, who had undergone at least a form of religious conversion. He tells us, 'My father had acquired some knowledge of letters before he was a soldier, and later on his passion for learning was such that he intended all his sons to have instruction in letters before they were trained to arms.