Mass Disability - how did I come up with 40%?

How, a friend asked, did I come up with the 40% number for “mass disability” that I quoted in After Trump: reflections on mass disability in a sleepless night?

I came up with that number thinking about the relationship of college education, IQ curves, and middle class status. The thesis goes like this…

1. Disability is contextual. In a space ship legs are a bit of a nuisance, but on earth they are quite helpful. The context for disability in the modern world is not climbing trees or lifting weights, it’s being able to earn an income that buys food, shelter, education, health care, recreation and a relatively secure old age. That is the definition of the modern “middle class” and above; a household income from $42,000 ($20/hr) to $126,000. It’s about half of Americans. By definition then half of Americans are not “abled”.
2. I get a similar percentage if I look at the percentage of Americans who can complete a college degree or comparable advanced skills training. That’s a good proxy for reasonable emotional control and an IQ to at least 105 to 110. That’s about 40% of Americans — but Canada does better. I think the upper limit is probably 50% of people. If you accept that a college-capable brain is necessary for relative economic success in the modern world then 50% of Americans will be disabled.

So I could say that the real number is 50%, but college students mess up the income numbers. The 40% estimate for functionally disabled Americans adjusts for that.

As our non-sentient AI tech and automation gets smarter the “ability” threshold is going to rise. Somewhere the system has to break down. I think it broke on Nov 8, 2016. In a sense democracy worked — our cities aren’t literally on fire. Yet.