(7) The words "existential" and "factical" should be...

(7) The words "existential" and "factical" should be distinguished from those of "intentional" and "factual." I use them in Heidegger's sense, which is based on his theory of Dasein as "being-in-the-world-with-others." As for Heidegger's concepts of "existence" and "facticity," see Heidegger, (1962), pp.78-86; 235-[^241]: (8) In hisA Theory of Justice , John Rawls makes a careful distinction between "obligation" and "natural duty." According to Rawls, both "obligations" and "natural duties" are moral requirements.

Their main distinction consists in the following three aspects: (1) obligations "arise as a result of our voluntary acts" while natural duties "apply to us without regard to our voluntary acts"; (2) "the content of obligations is always defined by an institution or practice the rules of which specify what it is that one is required to do" while natural duties "have no necessary connection with institutions or social practices; their content is not, in general, defined by the rules of these arrangements"; (3) "obligations are normally owed to definite individuals, namely, those who are cooperating together to maintain the arrangement in question" while natural duties "hold between persons irrespective of their institutional relationships; they obtain between all as equal moral persons" (Rawls, p.113; p.115).

On the one hand, I agree with Rawls in saying that one moral requirement arises from voluntary acts while the other does not, although I don't want to use the word "obligation" exclusively for those moral requirements based on voluntary acts. In many cases, as we know, "obligation" and "duty" mean the same in our ordinary use of English.

For example, we see this in sentences such as "Citizens have an obligation to observe the laws of their country;" or "Mentally gifted people are under an obligation to develop their capacities." Therefore, I use "moral responsibility" for those moral requirements cause by voluntary acts, "moral duty" for those which are not connected with the voluntary acts, and "moral obligation" for both.

On the other hand, I don't agree with Rawls when he says that the content of duties has "no necessary connection with institutions or social practice." Maybe he thinks that all social institutions, by their nature, have a voluntary or contractarian grounds. But we know that not all institutions or social practices, e.g., the family, are based on contractarian grounding. They are naturalistic social institutions.