This post assumes some familiarity with Kant’s moral theory. However, this is not exegesis of Kant’s thought. What I write is best interpreted as going off on a tangent* from the text to develop my own thoughts from a fragment of Kant’s thought. In this case, my own thoughts are those of my past three posts: “How do we prove a moral principle?” And “What is accomplished by a proof of a moral principle?”

The fragment of Kant’s thought is his first statement of the categorical imperative in his Foundation of the Metaphysics of Morals.**

It reads: Act only on maxims which you can will to be a universal law of nature.

In my previous post I came to the conclusion that relative to certain assumptions – a stance – a proper argument for a moral principle shows that activity in accord with the principle is rational activity and that activity in accord with the principle is directed towards attaining and maintaining conditions good for human beings over and beyond the good of being rational.

In the following I write of proofs as characterized above.

My Kantian speculation is that proof of a moral principle is showing that you can will a maxim to be a universal law of nature.

Let me illustrate this speculation with the principle for male sexuality of the previous post which I call the Paternal Principle.

As a maxim or principle for personal action the Paternal Principle becomes:

I shall not intentionally seek an orgasm except in coitus open to conception with a woman to whom I am committed for life to care for her and any child resulting from the coitus.

A “Kantian” proof that a man is acting in accord with laws of morality by following this maxim would show that any man acting in accord with principle is following a principle which is part of rational activity and is part of the human good of marriage. In other words, the proof shows what a rational seeker of human good would do. Any other course of conduct, for male sexuality, would be inconsistent with being a rational seeker of human good.

As the line of thought develops, an assumption that every human being is potentially a rational seeker of human good is a crucial assumption.

In light of such a proof one can will that nature be so constructed that every man actually acts on the principle on the basis of psychological-physiological laws of nature. But one could not consistently will that some potential seeker of human good be causally determined not to realize their potential.

In a way, the line of thought is that you can not consistently say “This is the way an ideal human being would act but in fact some human is not to act that way.”

This is far from standard ways of discussing Kantian generalization. The usual approach is to inspect a generalization of a maxim itself for consistency. The approach here is to consideration of consistency only after a moral proof of a principle has been presented. The question of consistency is “In light of a proof showing certain activity is what a rational seeker of human good would do, can maxims be consistently be willed as causal laws for what a rational seeker of human good does.”

I cannot resist alluding to the four examples Kant used to illustrate his categorical imperative.
1. Suppose it was shown that humans would flourish in their commercial life if all kept promises. It cannot be consistently that in a human society of rational seekers of human good some would not keep promises.
2. Suppose it was shown that rational seekers of human good made efforts to maintain their health and life. It cannot be consistently willed that it becomes a causal law that for such beings some choose to end their lives.
3. Suppose it was shown that rational seekers of human good made efforts to develop skills. It cannot be consistently willed that it becomes a causal law that some such seekers choose to develop no skills.
4. Suppose it was shown that rational seekers of human good made efforts to cooperate to help others attain human goods. It cannot be consistent will that it becomes a causal law that some such seekers become totally uncooperative.

* I have been off on this tangent for over twenty years

I wrote a book on Kant’s moral theory and religion It is
A Kantian Condemnation of Atheistic Despair: A declaration of dependence. Peter Lang, N.Y. 1997
See pp. 200ff for remarks on Kantian moral universalization.
See pp. 170 ff of my more recent book.
Confronting Sexual Nihilism: Traditional sexual morality as an antidote to nihilism, Tate Enterprises, Oklahoma City, 2014

**handle nur nach derjenigen Maxime, durch die du zugleich wollen kanst, dass sie ein allgemeines Gesetz werde AK IV 421

Translations of Kant’s Metaphysical Foundations of Morals will have the AK edition vol. and p. # in the margins.