as a principle of universal legislation.”  The possibility of conceiving the principle of volition as a universal law of nature is the criterion of morality.  If you are in doubt concerning the moral character of an action or motive simply ask yourself the question, What would become of humanity if everyone were to act according to the same principle?  If no one could trust the word of another, or count on aid from others, or be sure of his property and his life, then no social life would be possible.  Even a band of robbers cannot exist unless certain laws are respected as inviolable duties.

[Footnote 1:  The moral law, therefore, is independent of all experience in three respects, as to its origin, its content, and its validity.  It springs from reason, it contains a formal precept only, and its validity is not concerned, whether it meets with obedience or not.  It declares what ought to be done, even though this never should be done.]

[Footnote 2:  The “formal principle” of the Kantian ethics has met very varied criticism.  Among others Edmund Pfleiderer (Kantischer Kritizismus und Englische Philosophie, 1881) and Zeller express themselves unfavorably, Fortlage and Liebmann (Zur Analysis der Wirklichkeit, 2d ed., 1880, p. 671) favorably.]

It was indispensable to free the supreme formula of the moral law from all material determinations, i.e., limitations.  This does not prevent us, however, from afterward giving the abstract outline a more concrete coloring.  First of all, the concept of the dignity of persons in contrast to the utility of things offers itself as an aid to explanation and specialization.  Things are means whose worth is always relative, consisting in the useful or pleasant effects which they exercise, in the satisfaction of a need or of the taste, they can be replaced by other means, which fulfill the same purpose, and they have a (market or fancy) value; while that which is above all value and admits of no equivalent has an ultimate worth or dignity, and is an object of respect.  The legislation which determines all worth, and with this the disposition which corresponds to it, has a dignity, an unconditioned, incomparable worth, and lends its subjects, rational beings framed for morality, the advantage of being ends in themselves.  “Therefore morality, and humanity so far as it is capable of morality, is that which alone possesses dignity.”  Accordingly the following formulation of the moral law may be held equivalent to the first:  “So act as to treat humanity, whether in thine own person or in that of any other, in every case as an end, never as a means only.”