Sociologist Judy Singer coined the word "neurodiversity" in 1998. She wrote:
"For me, the key significance of the Autism Spectrum lies in its call for and anticipation of a politics of neurological diversity, or ‘neurodiversity.’ The neurologically different represent a new addition to the familiar political categories of class/gender/race and will augment the insights of the social model of disability. The rise of neurodiversity takes postmodern fragmentation one step further. Just as the postmodern era sees every once too solid belief melt into air, even our most taken-for granted assumptions: that we all more or less see, feel, touch, hear, smell, and sort information, in more or less the same way, (unless visibly disabled) – are being dissolved.”
From the Second MInd view, neurodiversity (the diversity of brains) is a reflection of psychodiversity (the diversity of minds). Furthermore, the Second Mind view does not establish one behavior or brain as fundamentally "neurotypical" or "psychotypical". These terms reflect a conscious or subconscious social agreement that confers certain advantages and disadvantages. In other words, there are only psycho-neurodiverse people. Each of us is psychodiverse, and therefore, neurodiverse, including across First and Second Mind configurations.
The question remains: At what point does psycho-neurodiversity become a disorder? This depends on the degree of overwhelm and suffering, which also depends on the level of insight in our society and the ability to create societal contexts that recognize and honor psycho-neurodiversity in its many ranges. To the extent that we are limited in either of these regards, overwhelm and suffering are more likely to set in along with ideas and experiences of disorder and disease.
(Thanks to Greg Murray for commenting and clarifying that neurodiversity "...does not contradict the existence of typicality. Typicality is important to point out because it brings norms and power structures that need to be known in order to be questioned." I agree with this view. We can recognize diversity and a range of expression across the entire population while also saying some subset of expression is more common or typical. The point I was making above is that from a Second Mind perspective, there is no particular typicality, which I hope will encourage us to create processes to allow a wider range of expression.)