Pick either Yes or No.. It's Scriptural.
Matthew 5:37 KJV
But let your 'Yes' be 'Yes,' and your 'No,' 'No.'
Are you a palterer? You can't answer that "Yes" or "No" unless you know what the term means.
So define "valid" --- a question can't be answered if the terms are undefined.
For instance: did Pope Benedixt XVI intend to abdicate the entiree papacy? Or does he see it as now a shared thing, with B16 still participating in the does he see it, as Ganswein suggested, a shared role in which he somehow retains the "munus" while Bergoglio exercises the active ministry with Benedict's (tacit?) authority?
OR: if the 2013 conclave was defective because of a prohibited level of "politicking" going on before, during and after the conclave, would that make Jorge Bergolio's election illicit? Or invalid
And what would be a orohibited amount of politicking? Would there have to be an actual quid pro quo?
And what would be a reasonable way to answer that last question? Asking Mrs. Don-o? Asking Elsie? Or asking canon lawyer?
Moreover, I acknowledge the duty to respect and observe the Papal Magisterium. Because that is valid. If Bergoglio's own personal teaching, inserted into the AAS and the Catechism, contradicts the Papal Magisterium, am I obliged to respect and obey the pope ("... *this* pope, *this present* pope," as the notorious Bishop Scicluna said...) OR the Papal Magisterium?
I know my answer to that. In any case of contradiction between the two, I follow the Magisterium, not "... *this* pope, *this present* pope".
That's because any contradiction to the Magisterium is invalid.
So. Internal contradiction is invalid. That's a product of reason, not just of Canon Law. If you wonder why, I'll be glad to answer.