It soon, emerges from any discussion about freedom of thought, with for example one's university colleagues, that the very idea of Catholics thinking freely still strikes many people as essentially funny. One quickly realises that many non-Christian intellectuals hold the view that Catholics are forbidden to think on pain of sin, heresy, excommunication and the whole apparatus of the Inquisition. But before discussing the peculiar difficulties of Catholics in this matter, I must say something in general about the meaning of freedom to think, asking the reader always to keep in mind its bearing on the particular problem of Catholic thought.

In order to consider whether we make the best use of the capacity for thought which we have (to which there are obvious limits set by native endowment both in the individual and in the species) it may be useful to establish the conditions in which thinking can occur at all.