21) It seems worthwhile to examine their thesis in the light of the documents which we have been reviewing, with a view to seeking some light on the disputed question regarding the nature and limits of this "secondary object" of infallibility--in particular whether it includes the norms of the natural moral law.
While Catholic theologians differ as to how much of the natural moral law is contained, at least implicitly, in revelation, there is general agreement that the modern world presents a great number of difficult and complex moral problems to which Christians seek solutions "in the light of the Gospel," but also in the light of human experience, by applying their intelligence to the search for the correct determination of moral right and wrong as applied to this kind of problem.
revealed by God, but also all those norms of the natural moral law which are not revealed, but which the Creator has "written in our hearts" (cf.
I understand Betti to mean that all questions pertaining to the natural moral law belong at least to the secondary object of infallibility.
The encyclical closes with an appeal to public authorities to oppose laws which undermine the natural moral law
, an appeal to scientists to further study effective methods of natural birth control, and appeals to doctors, nurses and priests to promote the method.