Unlike most of his contemporaries, Peter Abelard is a well-known thinker. General histories of philosophy give at least a passing mention to his theory of universals and, sometimes, to his ethics; whilst in surveys of the Middle Ages Abelard usually figures as the lover of Heloise and opponent of St Bernard, the representative of a new restlessness in intellectual life at the beginning of the twelfth century. Specialist work, too, has not been lacking. Almost every aspect of Abelard's work and life has been the subject of detailed study, from his logical and theological theories to his personal correspondence and the accusations of heresy made against him. Abelard is, none the less, a thinker who stands in need of a re-evaluation – and one which goes beyond the mere effort to compose a coherent picture from the mass of detailed research now available, or to provide a partial reinterpretation. For a single, underlying view has dominated discussion of Abelard's thought from the early seventeenth century, when a collection of his writings was first printed, until the present day.

This claim may seem surprising. Abelard was controversial in his lifetime and remained so after his death. The judgements of his work by historians seem, at first sight, sharply conflicting: some have seen him as superficial and misguided, whereas others have given him a hero's role in the development of philosophy. But, behind these differences, there emerges a remarkable agreement between his admirers and antagonists about the nature of Abelard's thought.