From Rorate's post on the Holy Father's address to Caritas:

In the political sphere - and in all those areas directly affecting the lives of the poor - the faithful, especially the laity, enjoy broad freedom of activity. No one can claim to speak "officially" in the name of the entire lay faithful, or of all Catholics, in matters freely open to discussion (cf. Gaudium et Spes, 43; 88). On the other hand, all Catholics, and indeed all men and women, are called to act with purified consciences and generous hearts in resolutely promoting those values which I have often referred to as "non-negotiable".

It would have been better if he would have said "not open for dialogue," since so many people think that even the most fundamental dogmas can somehow be subjected to dialogue. Dogma, by definition, cannot be the object of dialogue. The Church teaches these things. It cannot be taught.