Bioethics is understood in this article as one of the areas of applied ethics, i.e. as a philosophical discipline. From its very beginning, bioethics has been an area of controversy among ethicists representing different standpoints. The philosophical character of bioethics does not unambiguously determine the contents of the accepted norms. The reason for this is the fact that contemporary moral philosophy comprises many ethical theories which are the basis not only for bioethics, but also for other areas of applied ethics. Due to their diversity, the theories give diverging moral appraisals and norms. This divergence results from differences in methods of justification and in the anthropological premises accepted at the starting point of each of these theories. In this article two methods for justifying moral norms are examined, teleological and deontological. While these methods are also employed outside of bioethics, the following three arguments, (1) the playing God argument (2) the slippery slope argument and (3) the obligation for future generations argument, are typical of this discipline. The arguments consist in applying the general methods of justification to determine the moral permissibility of practical advancements in contemporary biomedicine.