In this chapter I present a new approach to public health ethics at two distinct, but related levels. First, I consider public health ethics at the level of duties towards those individuals comprising populations. This is the standard target, and the focus of the previous chapter, since most writers on this topic have deemed the notion of populations/the public as a “super-organism” implausible. Second, I consider the possibility of ethical duties towards populations as complex systems. With respect to both the individuals comprising populations, and the populations themselves (as complex systems), I propose the adoption of what I call "capacities-based principlism" - an ethical framework focused on developing the capacities of complex systems.