Necessary But Not Sufficient

A Sanity Factor or Sanity Check is something that is Necessary But Not Sufficient for something else.

For example, money for happiness.

After a certain point, it doesn't really help and will even harm. But it is required up to a point.

It's surprising that this concept isn't more formally defined, since it's a very basic concept in a lot of situations.

There's a book with the title - Necessary But Not Sufficient. But it's not clear if it's actually about this concept.

Sanity Checks appear to be a programming concept. Perhaps that's why it's not more commonly defined.

It's basically a check to see if the essentials are in place.

Here's a great example how this is a key missing conceptual framework, when considering the correlation of IQ against various outcomes. Quoted:

"It is quite plausible that one can obtain a university degree through conscientiousness despite modest cognitive aptitudes. There are many such individuals. But who is going to win a Fields Medal in mathematics, which recognizes the most brilliant young minds? A high IQ is not sufficient in this case. Not at all. But it is probably necessary."