WHETHER OR NOT THIS ACTION or PRINCIPLE, applied universally, ALLOWS A WORLD TO EXIST DETERMINES WHETHER OR NOT THE ACTION OR PRINCIPLE defineS MORALITY

CATEGORICAL IMPERATIVE

"A PRIORI" knowledge is key to the application of the categorical imperative. Example: all bachelors are, by definition, unmarried, and that is purely logical. Now, if a person makes the maxim "all people should not get married" a universal law, everyone in that world would be, by definition, bachelors. But, this means that no one would reproduce (a PRIORI) and this world would eventually cease to exist because every bachelor would die because they are human (this is also a PRIORI knowledge). Thus, the maxim is false according to the categorical imperative. See top.

A PRIORI, OF COURSE, connects to THE INTUITION through causality