 Thus at one pole, anti-naturalist ethical theories were derived from interpretations of current historical phenomena. Some of the anti-naturalist doctrines in ethics developed theses that were analogous to the religious doctrine of “original sin.” This tendency was evidenced by the popularity achieved by the writings of theological critics of Deweyan ethical naturalism such as Reinhold Niebuhr in the 1950s. The dual theme of these works involved both a descriptive interpretation of the perversity, malice and imperfectability of human nature, as well as an ontological or meta-ethical thesis about the need for a non-natural, that is, religious or rational-intuitionist basis and source for moral imperatives in human society and history.