Enhanced humans versus "normal people": elusive definitions.

A key aspect of transhumanist thought involves the modification or augmentation of human physical and mental capabilities--a form of intervention often encapsulated under the term "enhancement." This article provides an overview of the concept of enhancement, focusing on six major areas in which usages of the term become slippery and controversial: normal or species-typical functioning, therapeutics or healing, natural functioning, human nature, authenticity, and the ambiguity between "more" and "better." I argue that we need to be aware of the tendency to embed the concept of enhancement within stark binary oppositions that seem perfectly reasonable at first glance, but that in fact yield little more than conceptual muddles if they are not handled carefully.