At the moment I'm in a 'heated discussion' with the philosopher and writer Stephen Law regarding our Moral Stance on Homosexual Acts and The use of Condoms in cases of h.i.v./A.I.D.S.
This has led me to refer to a wide varietyof allegedly 'catholic' commentators/experts who , to be quite frank, more than a few wouldn't know a thing about fundamental catholic moral theology if it bit them on the bum ! Some of the worst are pragmatic situationists whose only consistency is countering any orthodox morality with a pseudo ipsissive narcissistic utilitarianism.
One of the biggest mendacities doing the rounds is the status of Thomism - as if it is now defunct ?
Well, big thanks to the Totus Pius blog for this:
Myth: “Thomism is no longer considered to be the philosophia perennis. Although Leo XIII declared it so in the encyclical Aeterni Patris, John Paul II in his more recent encyclical, Fides et Ratio, is less insistent on the primacy of the philosophy of St. Thomas. He writes, ‘The Church has no philosophy of her own nor does she canonize any one particular philosophy in preference to others.’” 
Reply: A close reading of Fides et Ratio shows that this is not the case. Despite John Paul II’s toning down of Leo XIII’s rhetoric, he presents the same argument as Pope Leo.
In paragraph 4 of the encyclical, John Paul II establishes the existence of an “implicit philosophy:” “a body of knowledge which may be judged a kind of spiritual heritage of humanity. (cross-reference with definition of philosophia perennis)”  He proceeds to list the elements of implicit philosophy.
Some of these elements are: non-contradiction, finality, and causality. Anyone who has read St. Thomas knows that in paragraph 4 of Fides et Ratio John Paul II is stating that the first principles of St. Thomas’s philosophy are the implicit philosophy of the Church.
Furthermore, he argues later in the encyclical that this implicit philosophy is the criteria for judging all other philosophy that may be of service to the Church.
All of this has led Prof. Ralph McInerny to conclude that
“Thus, despite the apparent acceptance of philosophical pluralism and its irenic attitude toward historical developments in philosophy—admittedly balanced by severe criticisms—and despite the seeming soft-pedaling of the primacy of Thomas Aquinas, the net effect of the invocation of an implicit philosophy is to make the thought of Thomas regulative in a fundamental way.”1
Myth: “I still don’t believe you. How does all of this reconcile with John Paul II’s statement in the encyclical, “In different cultural contexts and at different times, this process has yielded results which have produced genuine systems of thought. Yet often enough in history this has brought with it the temptation to identify one single stream with the whole of philosophy. In such cases, we are clearly dealing with ‘philosophical pride’ which seeks to present its own partial and imperfect view as the complete reading of all reality.”
Reply: This statement does not apply because Thomism is not a “philosophical system.” St. Thomas presupposes the principles of implicit philosophy. As Prof. McInerny says in the same article, “Since these starting points or principles of Thomism are in the common domain, Thomism is not a system of philosophy, if a system is defined in terms of peculiar and distinguishing first principles.”
Myth: “Well, I still don’t accept the arguments. Just because every pope since St. Pius V who has written on Christian education has affirmed the primacy of St. Thomas Aquinas as philosopher and theologian doesn’t mean it’s a law or anything.
Reply: Sorry, sweetie, Canon 251 states, “Philosophical instruction must be grounded in the perennially valid philosophical heritage and also take into account philosophical investigation over the course of time. It is to be taught in such a way that it perfects the human development of the students, sharpens their minds, and makes them better able to pursue theological studies.” How do we determine what they mean by “perennially valid philosophical heritage?” The encyclicals which are unequivocal.∗The term suggests a set of beliefs common to all peoples and times.
1. “The Scandal of Philosophy: Reconciling Different Philosophical Systems According to Fides et Ratio”