Problems with formal models of epistemic entrenchment as applied to scientific theories

Formal models of theory contraction entered the philosophical literature wi th the prototype model by Alchourron, Gardenfors, and Makinson (Alchourron et al. 1985). One influential model involves theory contraction with respec t to a relation called epistemic entrenchment which orders the propositions of a theory according to their relative degrees of theoretical importance. Various postulates have been suggested for characterizing epistemic entren chment formally. I argue here that three suggested postulates produce inapp ropriately bizarre results when applied to scientific theories. I argue tha t the postulates called noncovering, continuing up, and continuing down, im ply respectively that, (i) no scientific law is more epistemically entrench ed than any of its instances, (ii) two distinct instances of the same scien tific law must have different degrees of epistemic entrenchment, and (iii) any two scientific laws must have different degrees of epistemic entrenchme nt. I also argue that continuing up and continuing down each lead to incohe rency.