Paul Simon made use of Martin Carthy's arrangement of Scarborough Fair. It was his own idea to incorporate Canticle into it - and a very clever one too. Martin was, however, the first person on the revival to resurrect the song and so deserves credit as an arranger. Paul, however, has never collected a writer's royalty on it and therefore 'stole' nothing. The two artists have long since reached an understanding over the issue and I suggest you all let it drop - or at the very least refrain from perpetuating a malicious and damaging myth.