It depends how you measure intelligence. Because you get people with phds at the very peak of knowledge in their specialised subject that can barely tie their own shoelaces. I know someone who could tell you anything you ever wanted to know about ancient languages but can barely function day to day. He has to write lists for absolutely everything he has to do. I’m not talking about things like “dentist at 10:30”, I’m talking about “get up” and “wash” and “eat” because he can’t remember to do them otherwise. Is he really intelligent, or does he have a natural aptitude for language? Or has he just put the hours in? Unless there’s a question in Aramaic, he’s shite at pub quiz nights too. Never again!

since i work in research I know a lot of people with PhDs or people who are working on their PhDs. i think a lot of them are smart, although there are a couple of stupid mfs sprinkled in there.

but intelligence really isn't the most important factor that contributes to someone seeking out and getting a PhD.

someone's access to education is one. getting a PhD is a HUGE sacrifice financially (you are BROKE for 5-7 years+) and not everyone is able to take that financial risk.

second is that simply not everybody knows what a PhD is or how attainable it could otherwise be for them. the people most likely to get PhDs are people who are NOT first generation college students.

there are lots of socioeconomic and cultural factors beyond intelligence that play into it. it's not simply a question of whether the individual is smart enough to do it

Oh definitely - what a PhD can do is demonstrate that someone can understand a subject matter deeply and apply a high level of reasoning to it - which is a process towards becoming intelligent in a lot of matters, and something they've drilled for several years to achieve for a PhD. That being said, the intelligence they've got doesn't necessarily equal wisdom (= intelligence v experience), so they might have very little intelligence in other areas - but not to say they can't learn it though. Theres a lot to learn in this world and judging someone for not knowing something you do when they've not had the opportunity to learn something yet is like beating a toddler at your favourite video game and calling them shit... and this arrogant judgement works both ways (people who judge academics, and academics who judge people who haven't attended University).