 Kant’s statement that each formula “unites the other two within it” initially suggests that the formulas are equivalent in meaning, or at least one could analytically derive one formula from another. Some of Kant’s commentators, for example, have argued along the following lines: That I should always treat humanity as an end in itself entails that I should act only on maxims that are consistent with themselves as universal laws of nature (O’Neill 1975, 1990; Engstrom 2009; Sensen 2011). There are remaining doubts some commentators have, however, about whether this strategy can capture the full meaning of the Humanity Formula or explain all of the duties that Kant claims to derive from it (Wood 1999, 2007; Cureton 2013).