"Deep brain stimulation should be confined to therapeutic contexts and to severe, otherwise treatment-refractory disorders in which the aim is to normalize brain functioning. Apart from this, it should not be used to modify a person's individual character traits and behaviour or to enhance human traits." - Hildt (2006) Electrodes in the brain: some anthropological and ethical aspects of deep brain stimulation (7 pages, pdf)
Hildt draws on two lines of argument to reach this conclusion. One involves medical risks and side-effects associated with brain surgery. The other is the Dehumanization Argument, characterized by concerns such as "technicalization of the human body, the encouragement of a reductionist, technological view on human beings, the fear of losing human identity, and speculations relating to cyborgs".
The fear of losing human identity is something I encounter often in discussion about the iPlant. We all accept that it is better if human nature is civilized - no one likes a brute - but we also feel that too much civilization, by a totalitarian state or exceptionally strict parents for example, takes away too much of our initial, organic human nature. Many people place psychopharmaca and brain implants in this category of things that may supress, damage or pervert the human spirit.
In his fantastic talk entitled 'Ambivalence of the Posthuman Condition' (20min, Changesurfer Radio) Erik Davis (personal website) offers a much more nuanced view. He attempts to find a middle-ground between this kind of anthropocentric bioconservatism and over-optimistic transhumanism. The posthuman condition like the postmodern condition, he speculates, is characterized by a loss of 'grand narratives', such as a static human nature and the inevitability of aging and death. Unlike Hilde, Davis doesn't 'take issue' with this, it's just the way it is, progress won't stop. He simply (for want of a better word) urges us to remain critical and creative, and not to loose sight of the quality and richness of the means in our messy technological pursuit of "crude or psychologically obvious" ends. It's an excellent talk. Good night.