  Principles of fairness and solidarity in AI ethics regularly overlap,
creating obscurity in practice: acting in accordance with one can appear
indistinguishable from deciding according to the rules of the other. However,
there exist irregular cases where the two concepts split, and so reveal their
disparate meanings and uses. This paper explores two cases in AI medical
ethics, one that is irregular and the other more conventional, to fully
distinguish fairness and solidarity. Then the distinction is applied to the
frequently cited COMPAS versus ProPublica dispute in judicial ethics. The
application provides a broader model for settling contemporary and topical
debates about fairness and solidarity. It also implies a deeper and
disorienting truth about AI ethics principles and their justification.
