Robert,robertk wrote: The reply is this: if any of the nikayas now extant in Theravada have a broken lineage then the Bhikkhus in them are not in fact bhikkhu as the ordination was invalid. However, there has been no proof of this at all. To take the case of the Dhammayut and mahanikaya in Thailand. the Dhammayut was not a new order- it came about because one monk decided to reordain under burmese mon monks. And while he may have had some doubts about the purity of the mahanikaya monks he never proved or even stated that the Mahanikaya were a broken lineage.
If one man was ordained as a Bhikkhu by a preceptor who had knowingly kept secret a parajika offence (and therefore wasn't a monk at the time of the ordination ceremony) would you still count him as a Bhikkhu?
What about if monks were being ordained in a siimaa that was invalid? Would their ordinations be valid?
Or if the person ordaining had an unusual way of pronouncing the Pali during the ceremony and often got it 'wrong', would their ordination be valid?