ENThe article deals with the similarities and the differences between interpretations of closed morality and open morality in Bergson's and Popper's theories. The article studies as well the interpretations of concepts of reason, instinct, obligation and love. The main difference consists in the point of view of the role of intelligence and social habits as the foundations of obligation. Both authors maintain that the ground of obligation in closed societies is not rational. Bergson asserts that the source of open morality is mystic love, as he looks for moral actions not based on any kind of constraint. He argues that natural obligation is a pressure or a propulsive force, and perfect morality has the effect of an appeal. Mystics are able to embrace all humanity in one simple indivisible love and suggest that we follow their example. It seems that Popper would call the open morality as described by Bergson a closed one, as it is not based on intelligent decisions. Popper argues that the appeal to love is dangerous. We will note some deficiencies in conduct that is grounded exclusively on rational reasons, but these deficiencies will not be sufficient reasons to prefer conduct that is based on the love of humanity, on the aspiration to bring human beings to happiness.