This article addresses two questions. The first question is this: "when ought teachers to encourage or discourage students' belief of a given proposition on the one hand (call this "directive teaching"), and when ought teachers to simply facilitate students' understanding of that proposition, on the other (call this "non-directive teaching") (cf. the work of Michael Hand)?" The second question is this: "which propositional content should curricula address?" An answer to these questions would amount to what I will call a "theory of propositional curricula content", by providing both a means for choosing content, and a directive for teaching that content. While the answer that I give to the second question is unlikely to prove exhaustive, I still consider that it would form an important part of the answer, hence the title a "towards a theory of propositional curricula content".