obstinateness

Yes, some opinionated obstinateness is good.

The noun is “obstinacy” or, less often, “obstinateness.”

“Wal,” said the hardened man, apparently relenting, “I acknowledge ye’ve been a good gurl; but why shed yur now speil all the chances o’ our gettin’ a good livin’ by yur obstinateness in bizness?

And their further design appears in their great triumphing, and rejoycing when any illiterate person hath gained any reputation for a Cure performed, especially where Physicians have been concerned, though the Patients neglect or obstinateness, have been the sole cause of this non-performance, and by their continued detraction from Physicians, and applauding themselves, hoping by the former, that people will think such Mountebanks able to do better Cures then learned Physicians, and then they can easily insinuate themselves superior to such Mountebanks, and consequently to Physicians.