The Metaphysical Elements of Ethics · Immanuel Kant
B. HAPPINESS OF OTHERS
It is inevitable for human nature that man a should wish and seek for happiness, that is, satisfaction with his condition, with certainty of the continuance of this satisfaction. But for this very reason it is not an end that is also a duty. Some writers still make a distinction between moral and physical happiness (the former consisting in satisfaction with one's person and moral behaviour, that is, with what one does; the other in satisfaction with that which nature confers, consequently with what one enjoys as a foreign gift). Without at present censuring the misuse of the word (which even involves a contradiction), it must be observed that the feeling of the former belongs solely to the preceding head, namely, perfection. For he who is to feel himself happy in the mere consciousness of his uprightness already possesses that perfection which in the previous section was defined as that end which is also duty. If happiness, then, is in question, which it is to be my duty to promote as my end, it must be the happiness of other men whose (permitted) end I hereby make also mine. It still remains left to themselves to decide what they shall reckon as belonging to their happiness; only that it is in my power to decline many things which they so reckon, but which I do not so regard, supposing that they have no right to demand it from me as their own. A plausible objection often advanced against the division of duties above adopted consists in setting over against that end a supposed obligation to study my own (physical) happiness, and thus making this, which is my natural and merely subjective end, my duty (and objective end). This requires to be cleared up.
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