Sentence:  Whereas Bultmann 's `` center '' position is structurally inconsistent and is therefore indefensible on formal <WSD>grounds</WSD> alone , the general position of the `` right '' , as represented , say , by Karl Barth , involves the rejection or at least qualification of the demand for demythologization and so is invalidated on the material grounds we have just considered . 
Meaning of the word marked with <WSD> tags:  a rational motive for a belief or action