The rational basis for Kant's moral stance is based on the categorical imperative . Any cultural practice or institution that involves the manipulation, degradation, or exploitation of another human being is one to which neither I nor any other rational being can reasonably consent. Such a practice or institution is wrong, not because it violates the terms of a contract or because some moral sentiment makes it seem painful to me, but because I would be irrational and thus fundamentally inhuman if I were to countenance such a thing in the case of others while rejecting it in my own case. And states are the vehicles for maintaining those rights. For Kant, culture is civilization or cultivation of enlightenment, talent, and beauty.
Culture fosters our moral lives.
Culture allows for the development of taste and talent. Good sense is the most evenly distributed commodity in the world, for each of us considers himself to be so well endowed therewith that even those who are the most difficult to please in all other matters are not wont to desire more of it than they have. It is not likely that anyone is mistaken about this fact.