How does Kant's moral philosophy define "goodness" and evaluate the moral worth?

Question

Philosophy.SE, this is my first time being here, hence please pardon my inexperience of phrasing the question.

I was discussing the moral philosophy of Kant vs the moral philosophy of the Christian religion on "doing good things" and such with one of my Christian friends. I myself adhere to Kant's views due to my early exposure to The Critique of Pure Reason. I told my friend that you act due to the categorical imperative, and he doubted that categorical imperative could define the term "morally good" without introducing a higher deity. Here was where I stuck, I am not very sure how Kant's universality argument circumvents this question.

Have Kant ever defined "morally good" anywhere in his works? Thanks in advance.

Answer 1

Moral Good

For Kant, "moral good" would be an autonomous will that chooses rationality over irrationality. The Categorical Imperative for Kant is purely the end result of an autonomous will acting with the utmost rationality.

Act only according to that maxim by which you can at the same time will that it should become a universal law.

The only requirement that a rational agent conform to the Categorical Imperative comes from the fact that an autonomous will adhering to it would be considered rational, and an autonomous will violating it would be considered irrational. Since a will that chooses rationality over irrationality is a moral good, we ought to conform to the CI.

^{Kant's Moral Philosophy at SEP covers this topic pretty well; check it out for further reading. I'm not overly fond of Wikipedia's coverage but it's a good supplementary read.}

Answer 2

The problem with Kant is that he equates 'rationally universalizable' with goodness. To get to the real definition of "goodness" you have to ask the question "Why does it seem 'good' to universally recommend this act?" You might say that stopping at stoplights is good because you can universally recommend it for all drivers. But that does not answer the question "Why do you consider stopping at stoplights good in the first place?" The answer to that question is resolved in your feelings about what happens when people fail to stop at red lights. Cars get smashed and people get injured or killed. That is the real reason you consider stopping at red lights 'good', and failing to stop 'bad'. Nobody has to ask himself about universalizability to know that being struck by someone who fails to stop at a red light is bad. Goodness is not discerned by reason, it is discerned by emotion.