Recent years have seen a growth not only in biological knowledge but also, and more significantly for teacher education, in the types of knowledge manifested in biology. No longer, therefore, is it adequate for teachers to retain a Mertonian or a Popperian conception of science. Today's teachers of science need also to be able to help their students discuss bioethics and the societal implications of biology, even when these are controversial and contested. Moreover, practical work can no longer be confined to "pure", "safe", and "confined" activities. These are increasingly rejected by students, validly, as boring or irrelevant. Instead, we need to help students undertake a range of activities that help them to develop criticality and the potential for action. While some may see this as an attack on science, I would argue that this attitude is akin to those who once held that religious education (in countries that permit it) should confine itself to "the faith".