"The fundamental doctrine of rationalism is the supremacy of human reason, which, refusing due submission to the divine and eternal reason, proclaims its own independence, and constitutes itself the supreme principle and source and judge of truth. Hence, these followers of liberalism deny the existence of any divine authority to which obedience is due, and proclaim that every man is the law to himself; from which arises that ethical system which they style independent morality, and which, under the guise of liberty, exonerates man from any obedience to the commands of God, and substitutes a boundless license. The end of all this it is not difficult to foresee, especially when society is in question. For, when once man is firmly persuaded that he is subject to no one, it follows that the efficient cause of the unity of civil society is not to be sought in any principle external to man, or superior to him, but simply in the free will of individuals; that the authority in the State comes from the people only; and that, just as every man's reason is his only rule of life, so the collective reason of the community should be the supreme guide in the management of all public affairs. Hence the doctrine of the supremacy of the greater number, and that all right and duty reside in the majority. But, from what has been said, it is clear that all this is in contradiction to reason. To refuse any bond of union between man and civil society, on the one hand, and God the Creator and consequently the supreme Law-giver, on the other, is plainly repugnant to the nature, not only of man, but of all created things; for, of necessity, all effects must in some proper way be connected with their cause; and it belongs to the perfection of every nature to contain itself within that sphere and grade which the order of nature has assigned to it, namely, that the lower should be subject and obedient to the higher.
"Moreover, besides this, a doctrine of such character is most hurtful to individuals and to the State. For, once ascribe to human reason the only authority to decide what is true and what is good, and the real distinction between good and evil is destroyed; honor and dishonor differ not in their nature, but in the opinion and judgement of each one; pleasure is the measure of what is lawful; and, given a code of morality which can have little or no power to restrain or quiet the unruly propensities of man, a way is opened to universal corruption. With reference also to public affairs: authority is severed from the true and natural principle whence it derives all its efficacy for the common good; and the law determining what is right to do and avoid doing is at the mercy of the majority. Now, this is simply a road leading straight to tyranny. The empire of God over man and civil society, once repudiated, it follows that religion, as a public institution, can have no claim to exist, and that everything that belongs to religion will be treated with complete indifference."Many goings-on in our current societal state were predicted in these two paragraphs alone. The supposed power of the majority to overturn natural law (as in the case of redefining marriage). The pursuit of pleasure being made the basis of law. The dictum that all people have a radical right to complete emancipation from participation in the demands of civil society. The animosity toward the Church, which nowadays has to defend its reason as well as its faith, since society has clearly done away with reason.
I encourage all of my readers to read this document in its entirety. It is not that long (as far as Papal encyclicals go), and the dialect is not a huge obstacle. In my ideal world, this would be read in every civics classroom across the land. The full text can be found here.