'We recognise and identify goodness, and degrees of good, and are thus able to have the idea of a greatest conceivable good' says Iris Murdoch [p.395], throwing her weight behind the ontological proof.
I don't see this at all. It's the 'and thus' that's screwy. Imagine the sentence recast with the word 'blue' replacing 'goodness': '...we identify degrees and intensities of blue ... and thus we must inevitably accept that there is a greatest conceivable blue.' To which we can only say: nope.