The aim of this thesis is to provide an argument that enhancement technologies are a form of enablement more significant than their physical effects; rather, that enhancement might be a fundamental element of humanity. This allows a refutation of the standard bioconservative position, that to increase capacity beyond that of a "normal" Homo sapiens necessarily defeats humanity, or at least nebulous aspects of it. I here argue instead that humanity is affirmed, and furthermore that enhancements are in fact inherently good, valuable, and worthwhile pursuits; on the assumption that it is, as critics of enhancements and transhumanism say, inherently good, valuable, and worthy of preservation to be human. I suggest thus that to enhance is the essence of, and the key to, the continuum of humanity. In the introduction, I set out the reasons why this type of research is increasingly necessary, namely that it is important to rationally consider the effects which new enhancement and related technologies will have on our persons and on our society. Secondly, it presents my rationales for taking liberal stances on questions such as the scope and definition of enhancement, the supposed therapy- enhancement divide, and on access to enhancement technology; in order to provide a reasoned base from which to build the core themes of the thesis. It goes on to address a number of the archetypical critical arguments against enhancement, in support of these core themes.Part II of the thesis contains the papers and delivers the main arguments in sequence- firstly, the need for the application of rationality in policymaking and commentary on bioethical concerns, and secondly the importance of considering motivation when attempting to divine the best course of action to regulate beings and technologies that we have not yet experienced, and the manner of which we cannot entirely predict. This is followed by an argument as to whether it is reasonable to treat enhanced or other purported novel beings that could result from these technologies as different from ourselves, and thus warranting such policy considerations. To accomplish this, the thesis delivers a fresh angle on the relationship between Homo sapiens sapiens, the human, and whatever is posited to supersede it, the posthuman. A central theme is the idea that humanity is a "matter of sufficiency"- an end-state for moral status, not a stepping-stone which one can be 'post'. These arguments culminate in a contention that it is enhancement that acts as the unifying factor in our evolution and existence, and that there is therefore unlikely to be any good reason to see beings that follow the humans of today as being different in any significant way.The thesis concludes with an exploration of the progression of these themes, as well as identifying the place of my work amongst the wider academic literature around enhancement and the nature of the human. Finally, the most promising avenues for future research are explored.