Relativism due to underdetermination of theory by data

Three different versions of the underdetermination thesis are identified in the later writings of the Edinburgh School by which its relativism is maintained. These I call the Stratagems UT, the Floating‐feather UT, and the Oxygen UT. It is argued the marshalling of historiographical evidence to support the Floating‐feather UT involves a version of the Liar's paradox; that a variant of the Stratagems UT with the evidence provided by the Edinburgh School is internally inconsistent; that the Edinburgh School has failed to show the adequacy and the conformity of the historical evidence offered to support the Oxygen UT; that the Oxygen UT thoroughly neutralizes empirical evidence of any efficacy, and, thus, of any role, first, in the truth/falsity evaluation of the theory at the physical level, and second, in the explanation of theory‐evaluation at the explanatory metaphysical or socio‐historical level. I also show that Larry Laudan is quite mistaken in concurring with the Edinburgh School's thesis of symmetrical explanation of theories insofar as their epistemic status is concerned.