 As orthodox philosophy of science indicates, there are, in fact, many different considerations that speak for or against the rational acceptability of a theory or a view. Among the epistemic virtues of a theory are: its adequacy to the data; its simplicity, cleanness and elegance; its unity and freedom from ad hoc hypotheses; its explanatory and predictive power; etc. Not only do these (and other) criteria come in degrees, but they may also be orthogonal to each other. In the end, the rational evaluation of a view must balance it against all criteria of this kind (of which, consistency is, arguably, one), each, on its own, being defeasible. 