Answer:
It means basing the question on a premise that has yet to be established. For example if a random man in the street is asked, "Have you stopped beating your wife?", this begs the question by assuming he is married and that, if married, he beats his wife. The phrase is sometimes incorrectly used to mean "raises the question". For example, in the above someone might say "This begs the question, should there be stronger laws against wife-beating?", when they should correctly say, "This raises the question, should there be stronger laws against wife-beating?"