 Although debates concerning the reality or precise nature of emergence are largely driven by contemporary scientific theorizing, the basic notion has quite a long history stretching back at least to Aristotle (384–322 BC). On Aristotle’s view, human beings, like other “secondary” substances, arise from a distinctive arrangement of the four material elements. While the mental powers of human beings require and are necessitated by such an arrangement, these powers are distinct from, and downwardly causally efficacious with respect to, any non-mental powers. Furthermore, Aristotle’s form/matter compound conception of material substances is consonant with the standard emergentist stance between substance dualism and reductionism. For detailed discussion, see Caston (1997). Among Peripatetic philosophers, Alexander of Aphrodisias (late 2nd–early 3rd century AD; in On the Soul) and Galen (129–c.200; in On the Elements According to Hippocrates and elsewhere) develop distinctive versions of Aristotle’s basic emergentist picture to apply to chemical compounds and other non-living phenomena as well as living beings. (For discussion of several texts, see again Caston 1997: 347–353.)