In this article it is contended that individual arguments regarding abortion are dependent on a few prior questions. The answers given to these questions determine the view that a particular writer has of abortion. These questions deal primarily with the nature of law and of ethics respectively and with the relationship between the two. When answering these questions most writers fall in one of two categories. They are of either a posivistic or a natural law persuasion. In the first section the basic tenets of these two schools of thought are examined. In the second section the various arguments regarding abortion are examined in the light of the answers given in the first section. It is found that all arguments rest on implied or explicit preconceived ideas. These preconceived ideas are determined by the way in which a writer sees the relationship between law and morality. The conclusion is that philosophical ideas determine not only the answers to "philosophical questions, but also everyday questions such as the legal rules that should be followed in cases of abortions.