Rationalism

The tradition is rationalism and it comes to us from Plato and Kant and the recent utilitarians. It tells us that pure reason, in abstraction from desire, feeling, and traditional ways of life, is the sole route of access to moral facts. Since its maturation in the Enlightenment, it has been largely leftist, promulgating 'progressivism' as the march toward ever more rational values. It has Truths:

War is wrong.

All people are equally deserving of prosperity.

No one is better than anyone else.

These truths come from on high, from the realm of pure reason. They can be grasped when one takes a "view from nowhere" (one of liberal progressivist philosophy professors' favorite Kantian phrases). Stepping outside of your desires, tradition, and particular place in the world you see that the three statements above are axiomatic, unassailable, obviously true, and the knowledge of them is incorrigible. Rationalism thus breeds dogmatism right away. Once we leave behind empirical reasoning, which is the only kind of prudential reasoning there is, dogmatism is unavoidable. In addition, the disavowal of tradition and local preference is written into the creed of rationalism. The rationalist will be a leftist and he ineluctably must finally crush tradition and preference-based resistance under his jack-booted heel. The values upheld on the basis of tradition and preference are meaningless, irrational, unfounded, and brutish. There is no compromise with brute desire; it simply must be defeated.

But the notion of Moral Truths of Reason having specific and non-trivial content is gibberish. Pure reason tells you nothing at all about how to act or how to live your life. If you rely on it exclusively and dogmatically, you will end up with absurd pronouncements such as the three above. Just some of the falsehoods entailed by those three are the following:

It is wrong to have a military or use one to defend your country against an evil attacker.

Justice requires that we redistribute the wealth to absolute equality (or its Rawlsian utilitarian variant).

We should encourage all ways of life, no matter what the empirical evidence tells us about their effects.