The Novus Ordo: Valid but Illicit?

I’m not a theologian.  But as a lawyer, I’m pretty good with reasoning and logic.  And logic has me wondering whether the Novus Ordo Mass could be considered illicit.  If the Novus Ordo Mass was not authorized, it might be valid but illicit.  And if that’s the case, a strong argument could be made that attending a Novus Ordo mass is a grave sin.  For example, the masses of the SSPX are valid because the priests are, in fact, ordained, but illicit because they are not authorized to say Mass.  Accordingly, Catholics are routinely counseled to avoid SSPX masses.

So the next question is whether the Novus Ordo Mass was authorized.  Did Pope Paul VI have the authority to write a new radical Mass, as he did with the Novus Ordo?  The Papal Oath, taken by all newly-elected pontiffs states:

“Disciplinam et ritum Ecclesiae, sicut inveni, et a sanctis praecessoribus meis traditum reperi, illibatum custodire.” (“I promise to keep inviolate the discipline and the liturgy of the Church as I have found them and as they were transmitted by my holy predecessors.”)  

If Pope Paul VI broke this oath by failing to keep inviolate the liturgy (and the discipline) of the Church as he found them and as they were transmitted by his holy predecessors, could such a rite be legitimately considered licit?  As with the priests of SSPX, whose masses are valid but illicit, surely the Novus Ordo masses must be valid.*  But are they licit?  And if they are not licit because Paul VI broke his oath in instituting the Novus Ordo rite, they should be avoided in the same way people are counseled to avoid SSPX masses.

Here is the argument, laid out as syllogisms.  Decide for yourself.

First syllogism:

Major Premise: A Mass that is not authorized is illicit.  Minor Premise: The masses of SSPX priests are not authorized, because SSPX priests are not authorized to say mass.  Conclusion: The masses of SSPX are illicit.

Second syllogism:

Major Premise: A Mass that is not authorized is illicit.  Minor Premise: The Novus Ordo rite was not authorized because Pope Paul VI broke his Papal Oath in instituting it.  Conclusion: The Novus Ordo mass is illicit.

*Section 1248(1) of Canon Law addresses how to fulfill the Sunday obligation.  According to that Canon, participating in a mass celebrated according to a “Catholic rite” fulfills the obligation.  If the Novus Ordo mass is not an authorized “Catholic rite,” it may not fulfill the Sunday obligation, and therefore might not even be considered valid.