Taking as reference point Evandro Agazzi's publications on the ethics of science, this contribution discusses the development of ethical reflections on science and technology during the last decades. The article shows that former debates on the ethical liability of science turned to understanding ethical appraisal as a necessary part of scientific and technological projects. Ethics of science is treated not just as moral reflection on scientific activity, its ends, means and consequences, but as one of the fields of science studies, which is involved in the search for answers to the fundamental question "what is science?"