“Hume’s definition of a miracle is often attacked on a variety of grounds. Sometimes, the objection is made that miracles are not really violations or transgressions of natural laws. Since these laws are descriptive, rather than prescriptive, it is misleading to describe God’s action in deviating from them, on occasion, as a violation of a law. A useful point is being made here, and some people are no doubt misled by the connotations of the words “law” and “violation.” However, what many philosophers (including perhaps Hume himself) mean by a violation of a natural law is simply an exception to the normal processes of nature. This is quite consistent with a descriptive understanding of natural laws.
Another objection to the Humean definition argues that miracles are not really exceptions to the laws of nature. Natural laws describe what will occur, given a particular set of initial conditions. When those conditions do not hold, the law is not applicable. When a miracle occurs, however, the initial conditions will necessarily be different, since God’s special activity will be part of those conditions. Therefore, the law has not really been violated.” – Excerpt from Philosophy of Religion: Thinking About Faith by C. Stephen Evans and R. Zachary Manis