ABSTRACT
The prevailing idea that claims for truth and knowledge are ahistorical has a number of presuppositions which are initially formulated in Platonism, and re-stated much later in contemporary realism. These include the conviction that there is a single, permanent, mind-independent external world, and that we know it as it is, for instance in isolating items of knowledge, or so-called facts which are strictly independent of frames of reference, or at that we at least know the world as it is from the different angles of vision provided, say, by the difference between folk and scientific perspectives, or between different scientific theories.
