Ph.D. Training?

A while back, Brian Leiter and Dan Solove debated whether you need "Ph.D. training" to do cutting edge interdisciplinary work. If actually having a Ph.D. is a necessary condition, doing cutting edge interdisciplinary work in one's (first) dissertation would be out of the question. To be sure, no candidate for a (first) Ph.D. could be required to do cutting edge interdisciplinary work; that would be an awful Catch-22!

On the other hand, "Ph.D. training" might comprise the work that gets you to the ABD level, or it could be the collaboration with a mentor that is part of the dissertation process. However, a dedicated scholar can get to an "ABD level" of competence in another field on one's own, or with limited coursework, and you don't need to be a Ph.D. candidate to collaborate with a mentor who does cutting edge work. So, either you don't need Ph.D. training, or "Ph.D. training" needn't be someone that requires or leads to a Ph.D.