No one says it was the only way? But one of the requirements of getting that PhD is to expand knowledge so it's 100% applicable

You might be surprised to learn it doesn't actually suggest a PhD is the only way to expand human knowledge. No one was disregarded.

I don't think it's meant to do that. Also if we substitute PhD for learning both will be true.

As their specialised knowledge reaches the edge of the circle, their general knowledge updating should retract.

Everyone has met a PhD that is almost entirely clueless in other areas. Not their fault though, don't get me wrong.

Edit: The person that downvoted must be Dr. Climate Change Denier. Dr. Covid Denier has joined the fray.

Presumably you could meet the boundary with "a dollah fifty in late fees at the public library" and find a way to push through from there. You'd have to find a way to publish or share your new knowledge. Studying at uni gives you access to experts in their own thing that likely have knowledge that could help you with your thing as well as a system designed to churn out these papers when you eventually find your thing.

Every day people discover new things but it takes attention, effort, and will to PROVE it's a new thing and more yet to share that with the world. Too bad you can't get an honorary PhD for doing that, at least not reliably.

Good luck expanding the fields of math and science without a PhD.

Yes but how will I feel good that I spent 140k on a piece of paper if I don't brag about it?