This book is concerned with epistemic relativism in the sociology of scientific knowledge (SSK). However, though this is the main topic of the book, it is not restricted to this topic completely. First of all, I think that the book can also be read as a book on epistemic relativism in general. Though I will discuss mainly the position of the two sociologists Barry Barnes and David Bloor, I think that the arguments that I discuss are the main arguments to be found in the literature on epistemic relativism in general.