a definite (/fixed)argument (/opinion); an irrefutable (/unchange able) argument; a perfectly sound proposition; an unalterable truth
❍ 他的这种看法绝非～。This view of his is not at all an unalterable truth.
不易之论bù yì zhī lùn
易：更改。不可更改的议论。形容完全正确。perfectly sound proposition, undeniable truth, irrefutable argument, unalterable truth