The philosophies of the pre-Socratic Greek Sophists are controversial among scholars in general, due to their highly subtle and ambiguous writings and also to the fact that they are best known as characters in Plato's dialogues. Gorgias, however, is particularly frustrating for modern scholars to attempt to understand. While scholars debate the precise subtleties of the teachings of Protagoras, Hippias, and Prodicus, they generally agree on the basic frameworks of what these thinkers believed. With Gorgias, however, scholars widely disagree on even the most basic framework of his ideas, including over whether or not that framework even existed at all. The greatest hindrance to scholarly understanding of Gorgias's philosophy is that the vast majority of his writings have been lost and those that have survived have suffered considerable alteration by later copyists.