Catholic moral teaching is done by starting with a premise: For example, the "natural end" of sexual intercourse is procreation. One then logically goes from there to a conclusion: All sexual intercourse must be open to procreation. The problem is if the premise is flawed, then the conclusion must be wrong. 

MSW is correct when he says that moral teaching must be rooted in dogma. He neglects to say that it must also be rooted in reality. All too often, it really isn't. The argument that women cannot be ordained is rooted in the flawed assumption that women are inferior to men. The argument of Humanae Vitae is rooted in the flawed assumption that the natural end of sexual intercourse is procreation. 

Added to this is the assumption in the institutional Church that knowledge of a subject is not actually necessary when coming to a conclusion about it. Thus, we have had synods on marriage and the family not a single married person participates. The teaching on sex is made by the celibate