Chapter 6 focuses on functions and teleology in biology. Views on the metaphysics of function, teleology and design in the natural world include strongly realist views, weaker realist views (naturalistic reductionism) and anti-realist (e.g. eliminativist) views. These are views in scientific ontology: they concern the metaphysical inferences we should draw from evolutionary science. Does the science license the inference that teleology and design exist in the natural world in a real, literal and irreducible sense? Or does it license rather the inference that teleology and design exist in the natural world in a real, literal but reducible sense? Or should we rather infer from modern evolutionary theory that teleology and design do not form part of the natural world? Again, we find that views on scientific ontology are largely a function, or outgrowth, of epistemic stances. Realism about teleology and functions as implicit entities of science requires at least the MoS stance. Naturalistic reductionism about functions requires only the weak form of this stance, while strong realism requires at least the strong form of the stance, and possibly the armchair metaphysics stance, depending on one’s perspective, indeed, of one’s stance. Full-blooded anti-realism about functions is sometimes motivated by the empiricist stance.