Any physical theory can give rise to various kinds of conceptual difficulty. Problems may arise because of lack of familiarity with, or misunderstanding of, new ideas. Most students upon their first encounter with calculus or with special relativity have difficulties of this sort, which can be cleared up by additional study, working through examples, and the like. In addition theories may be internally inconsistent. This is often the case when they are relatively new and under development, but can also be true of more mature theories. Indeed certain theories turn out to be of great usefulness despite the fact that they contain serious flaws or inconsistencies. (Standard, which is to say textbook, quantum mechanics is a prime example!) And even theories which are properly understood and are internally consistent can be rejected, either by individual scientists or the community as a whole, because they are not “good physics”, a term whose importance should not be underestimated even if it cannot be given a precise definition. The histories interpretation of quantum theory has given rise to conceptual difficulties that fall in all of these areas, and while it is impossible in a few words to discuss each of them in detail, the following remarks are intended to indicate the general nature of some of the more serious issues raised by critics, along with responses made by advocates of the histories approach.  Griffiths (2014).--> 