But, the Central problem of medieval scholasticism was the problem of the ‘Universeals’.Although we are today accustomed to considering this as an epistemological problem, it was formulated in the Middle Ages as a primarily ontological one: are genus and species used in thought also something real? In other words, can the mind´s capacity to understand universally what is actually particular be explained in terms of something universal in the known? The Platonic, ultra-realist answer is obvious: the real ‘reals’, the ‘ideas’, are universal and any traces of universality found in the empirical world are due to the fact that the ‘shadows’ retain some resemblance to the ‘ideas’. Medieval nominalism reduced the universal to a flatus vocis (mere word) . The intermediate solution – the universal is properly mental but has a fundamentum in re (‘a basis in the thing’) – is often called ‘moderate realism’ to distinguish it from Platonic ‘ultra-realism’. (See the 84 question of Thomas Aquinas Summa Theologica for a succinct presentation of the moderate position on knowledge).(Soviet Theory of knowledge).
His writings (Roscelin´s) have been lost, except for a letter to Abelard, and we have to rely on the testimony of other writters like St. Anselm, Abelard and Joh of Salisbury. These writers make it perfectly clear indeed that Roscelin was an opponent of ultra-realism and that he maintained that only individuals exist, but his positive teaching is not so clear. According to St. Anselm, Roscelin held that the universal is a mere word ( flatus vocis) and accordingly he is numbered by St. Anselm among contemporary heretics in dialectic. Anselm goes on to remark that the se people think that colour is nothing else but body and the wisdom of man nothing else but the soul, and the chief fault of the ‘dialectical heretics’ he finds in the fact that their reason is so bound up with their imagination that they cannot free themselves from images and contemplate abstract and purely intelligible objects. (A history of philosophy. P. 143).