Prof. Mark Liberman (Language Log) has a long post on this. It starts by explaining how the phrase “beg the question” came to mean “assume the conclusion” (I hadn’t known that story), discusses how it often came to be used to mean “raise the question,” and finishes with wise advice:
Never use the phrase yourself — use “assume the conclusion” or “raise the question”, depending on what you mean — and cultivate an attitude of serene detachment in the face of its use by others.