In celebration of the fortieth anniversary of the publication of Beauchamp and Childress’s Principles of Biomedical Ethics, a review is undertaken to compare the lists of principles in various bioethical theories to determine the extent to which the various lists can be reconciled. Included are the single principle theories of utilitarianism, libertarianism, Hippocratism, and the theories of Pellegrino, Engelhardt, The Belmont Report, Beauchamp and Childress, Ross, Veatch, and Gert. We find theories all offering lists of principles numbering from one to (...) ten. Many of the differences can be reconciled, but some critical differences remain. (shrink)