How do we define morality?
Descriptively to refer to certain codes of conduct put forward by a society or a group? or accepted by an individual for his or her own behavior? or a code of conduct that would be put forward by all rational persons?
By conducting a fair behaviour, based on reasoning, we can ensure ourselves that our judgements are rooted in a universal morality that could be applied for all, including ourselves.
A mind of pure reason, freed from the desires of the selfishness, is rooted in human freedom.