  Butler’s best-known arguments for the natural hierarchy of principles draw on a number of analogies: to a watch (“Preface”), to a civil constitution (Sermon III), to a tree, and to a machine (Sermon 3 Note 1). Just as a clock is not an individual gear, or a pile of gears, but is what it is due to the ways in which the gears move together towards an end, so too human nature is not a particular principle of action, or a bundle of principles, but the interaction of principles, desires, and reasons, as a system towards ends. That our nature is structured towards ends, which Butler takes to be empirically evident, gives evidence of a hierarchy of principles to attain the ends, a hierarchy where some principles must be naturally subordinate to others (N3). This shows that there is something natural to us in the sense of N3, in addition to N1 and N2 (both of which are a matter of observed fact). “A civil constitution implies in it united strength, various subordinates under one direction … a superior faculty whose office it is to adjust, manage, and preside over them,” (Sermon III §2). The governing faculty has authority. When a civil constitution is violated or overthrown by “meer power” this goes against the nature of the constitution. When a machine’s or a tree’s parts no longer bear proportionate relations among themselves and are no longer guided by superior principles, it is broken or sick. By analogy, when forceful principles and passions (N2) go against authoritative principles (N3), or when the principles and passions no longer bear the same relations or are in conflict this goes against our nature and is unnatural. The analogy suggests that it is unnatural when a N2 principle overpowers a N3 principle. The subordination of N2 principles to N3 principles is natural and preserves and guides our natures. N3 principles are what we ought to act on or act in accordance with. Deciding whether Butler holds that we ought to act on them just because they are in accordance with our nature or we ought to act on them because they are morally right and in accordance with our nature has led to some of the most salient objections to Butler’s moral philosophy (see Section 4).