Ecclesiam Suam §102

¹⁰² In these circumstances dialogue is very difficult, not to say impossible, although we have today no preconceived intention of cutting ourselves off from the adherents of these systems and these regimes. For the lover of truth discussion is always possible. But the difficulties are enormously increased by obstacles of the moral order: by the absence of sufficient freedom of thought and action, and by the calculated misuse of words in debate, so that they serve not the investigation and formulation of objective truth, but purely subjective expediency.