Upward Mobility, Downward Society

In the US, the correlation between IQ and income is quite strong and it is growing stronger over time. It is sufficiently strong that proponents of embryo selection use this basis to justify the amount of money spent on IVF and selection.

Younger cohorts gain even more income by being smarter

The tendency for Americans to find themselves at the level of achievement that their skill would set as likely for them is often called The Sort. The benefit to individuals of The Sort being good is obvious: each person receives reward commensurate with their ability to achieve. For those with a high moral foundation of proportionality, this is an axiomatic good.

One assumption one might make is that what is good for the best among us is good for all of us. But that is perhaps not true. The Sort rewards high achievers with greater monetary reward, thereby bestowing upon them greater comfort and to some degree, power. But as it does that, it places people of lesser skill in positions where the surplus generated by greater skill is not extractable.

Therefore, increased mobility actually leads to a decline in societal well-being. This can be observed in a comparison of a few societies: the US, the UK, and Japan.

• Japan has low economic mobility. You can be smart and able and still the amount of money you make is unlikely to be very high. A few will make it but it's not the general case.

• The UK is somewhat in the middle. Most of the most able people tend to finance or tech where they can extract as much surplus as possible but there is a historical cachet to roles in government.

• The US has very high economic mobility.

While incomes in the countries go Japan < UK < US, it's easy to see by interacting with low remuneration services that the quality of them is Japan > UK > US. That's because the filtering process in the latter countries leaves the dregs to operate many things that exceed their skill.

In a low mobility society, almost every job is done by someone within whose grasp it is to do the job. In a high mobility society, the person reaches the job where marginal promotion would lead to low performance. Given sufficient such people, there are sufficient opportunities for such jobs to exist. The resulting upward filtering leaves many jobs to a population of people the smartest among whom are insufficient.

Consequently, American trains leave their passengers behind (and derail all the time) while Japanese trains that travel much faster have never suffered a fatality while running. The UK Government Digital Service is exemplary, while 18F had to be hastily assembled in the US from private sector superstars to rescue healthcare.gov.

For a society to have a generally high quality of life there is, therefore, a non-linear dependency on mobility. Too little and the underlying cause of lack of economic mobility is probably just a poor economy. But too much, and there is no one smart in the society where there isn't money to be made.