LeRoy Walters and Julie Gage Palmer's The Ethics of Human Gene Therapy (1997) includes one of the best discussions of the prospect of genetic enhancement that I've encountered to date. I've been rereading this over the past few days, and found this passage which really says it all, and highlights the difference between people who broadly favour changing human nature, and human capacities, and those who "don't get it". Here is what they say (it deserves quoting at some length):
"... a particular perspective on human nature clearly underlies our moral judgments about genetic enhancement. We are dissatisfied with and critical of certain aspects of the human condition as we see it reflected in the world around us and as we experience it. In the physical sphere, we regard disease and disability as evils that should be overcome as quickly and efficiently as possible. In the intellectual and moral sphere we have also identified serious problems that should be addressed in multiple ways, one of which is the judicious use of genetic technologies. We think that a certain dissatisfaction with human nature as it has developed and as we have inherited it is a prerequisite for intervention to improve human nature. Also implicit in the notion of genetic enhancement is a dynamic rather than a static view of human nature. While there are historical and evolutionary reasons for human nature's being as it is, we do not view the human race as being fated to accept the current state of affairs. Rather, we accept the possibility of change in human nature and have tried to argue for the ethical acceptability of certain kinds of planned changes in the characteristics of future human beings. In our view, such genetic enhancements are an important part of the overall task of attempting to provide a better life and a better world to our descendants." (page 133)
Unusually for me, I find I totally agree with this passage. Note that nothing here denies that we might, in practice, need to be very cautious about attempting genetic enhancement, or that there might be practical and ethical problems that are crucial barriers to particular experiments. The focus of the passage is on the big picture: that we do not have to take human nature as we find it.
I often make the point that we can never entirely step out of our own nature. This applies at both the individual level and the species level. If, for example, I am dissatisfied with some aspect of my own personality, and find it a barrier to achieving my goals, that is because it conflicts with desires that are themselves a product of my personality. As it happens, I am rather shy in social situations, a trait which I find annoying and frustrating - other aspects of my personality would better suited if I were less self-conscious and wary of others, a bit more extroverted, more relaxed about how others see me, and even able to be a bit more "pushy", etc., without embarrassment and the awkwardness that can go with it. However, all this is a problem only because it conflicts with the desires I actually have (although I find it difficult, I actually want to be gregarious and find social occasions energising, rather than emotionally draining, and to have the advantages of finding it easy to "network", and so on). I don't wish to jettison my entire personality and start again, just tweak aspects that don't fit well with my conscious desires - desires to be a certain way and to do, and enjoy, certain things.
There is no standard entirely external to us by which we are compelled to make changes to ourselves, but nor have our natures (as individuals or as a species) been designed for perfect harmony. At the individual level, we are the products of the genetic lottery and more-or-less chance occurrences in the process of socialisation as we've individually encountered it. There is no reason why our abilities and personalities should be expected to line up neatly with our desires or purposes. At the level of the species, we are a product of biological evolution that had no conscious goal. We have simply inherited genes that happened to confer more reproductive fitness than did their rivals in the environment of human evolutionary adaptedness. There is no reason to believe that they were the best genes for our ancestors' conscious happiness, let alone that they are best for our conscious pursuit of happiness, or whatever other conscious desires we have, in modern environments.
What we must concede is that it will be difficult to improve on what evolution has given us - not because we are perfectly designed by its processes but because we still have so much to learn about ourselves. For example, the underlying biological bases of our social nature need to be understood in much more depth before we take action that might hinder their operation. Accordingly, I am all for proceeding with caution and accepting that we may not see much change to human nature in our own lifetimes.
That acknowledged, it remains to be emphasised that we are conscious beings whose desires, purposes, and values go far beyond, and may even conflict with, reproductive fitness and with some aspects of our natures that once served it. If there is a genuine choice between maintaining our evolved physical and psychological nature as it is and tweaking it to something more conducive to getting what we consciously want for ourselves, then I'm all for doing the tweaking. On that point of principle, I am in good company with Walters and Palmer.