On Cyborgs, Cures, and Choices
I think he's wrong on both counts. As I see it, both neurodiversity and transhumanism are primarily about self-determination. When I write about neurodiversity, I am asserting that cognitive diversity is beneficial to the human species, just as other forms of diversity are valuable, and that people should never be forced to conform to some arbitrary concept of the ideal brain (whatever that might be) or treated as second-class citizens if they do not.
Whether or not a person's brain configuration is "natural" isn't the issue here. To me, neurodiversity means that every one of us is worthy of respect, acceptance, and equality—regardless of whether we were born with our current set of cognitive traits, or decided to take medication to alter some trait (such as to reduce anxiety), or chose to get some sort of cybernetic enhancement of the brain, or whatever. In a world that truly valued human diversity, a person wouldn't be judged as more or less valuable based on whether his or her brain was in its "natural" state, and there wouldn't be any coercion one way or the other.
As for the complaint that transhumanism views the natural body as diseased (which it does, to some extent, in seeking to cure the aging process), mainstream medicine already treats the degenerative conditions of old age as diseases—just not very successfully! There's a lot of research being done to find a cure for Alzheimer's disease, for instance, which is a major killer of the elderly. If we're including Alzheimer's and other age-related dementia in our definition of species typical cognitive functioning (as we should, because it is typical to develop some form of dementia in old age), the disease model is commonly applied. Not all that long ago, however, people took it for granted that "senility" was natural and inevitable. The recent change in society's attitude toward dementia didn't come from widespread acceptance of transhumanist philosophy; rather, it came from discovering the medical facts.
Although our scientific knowledge is still quite primitive in many areas, we already have reached a point where no citizen of a modern industrialized nation goes through life with his or her body in a natural, unaltered state. We have our teeth repaired with various artificial materials when they decay or are damaged, instead of believing it natural (as our ancestors did) to end up toothless in old age. Many of us choose to control our fertility with synthetic hormones. We wear contact lenses or have surgery to correct our nearsightedness, and if we develop cataracts as we age, we are likely to have artificial lenses implanted in our eyes.
I expect the vast majority of us would consider the availability of these modern medical technologies to be a significant advance for humankind, rather than lamenting that we're no longer constrained to live in a state of nature. While we do need to be vigilant to ensure that no medical procedures are performed against a person's will and to prevent discrimination on the basis of a person's mental or physical configuration (and I'm not just referring to disability discrimination here, but to all coercive expectations regarding the human body), there's no inherent contradiction between the values of neurodiversity and transhumanism. Both seek to expand our options in life and the diversity of our species.