certification/degrees are required to do plumbing

You’re obviously misconstructing my point, which was: Education, intelligence or contribution to society can’t be measured by a piece of paper or how long you’ve studied. I’ve met unschooled folks with wide knowledge and know-how and doctorates who can’t even cook (and vice-versa, obviously).

And people who get education in farming have higher yields

I’m not advocating against education, but education is a life-long process which doesn’t start or stop with a diploma. And if you’re talking about farming specifically, you may be aware that agro-education promoted since the “green revolution” in the 60s has terrible consequences for the environment, and that such mechanized/chemical agriculture has much lower yields over time than permaculture which is not taught in formal classes.

Being a PhD student is a full time job, more so than flipping burgers at a fast food joint.

I agree a PhD is a full-time job (though it shouldn’t have to be), yet arguing it’s more of a job than being a fast-food worker holds so much contempt. Having previously worked fast-food and currently doing PhD-like research in computer science i can assure you working a physical job for a boss takes a physical and mental toll that’s incomparable. Also worth noting, in your worldview (from what i gather) where everyone is restricted to a specific role (job) in society, it takes quite a few cooks to keep your PhDs fed, so they’re arguably just as valuable to society. My point was that without people to work the land, cooks, plumbers and builders, PhDs could not exist: occupations in a society are complementary [0].

why should they be paid less than those who have no education

I’m not saying that. I’m saying there’s no valid reason anyone should be paid more than anyone else. In fact, i’m saying in a fair society money would not exist (because money is the tool capitalists use to appropriate the wealth of others), but in the meantime everyone should be paid equally.

Additionally, if you don’t incentivize education through the chance of a higher quality of living, no one will go for it

You’re making a serious assumption which requires evidence. Humans (and other animals) are by nature curious and it takes quite a lot of resources/energy to disable that in people and turn them into subservient wage-slaves. You’ll notice that’s precisely what our educational systems (in much of the world) is about: learning obedience to authority, by-heart recitation and competition (cooperation is called “cheating”). So i argue that no matter how restrictive your society is, you can’t prevent people from asking questions and doing research (remember Galileo?), so man people will go for it. But i also argue that there’s plenty of ways we could make higher education and research more available to people throughout life instead of reproducing a caste system where scientists reside in their ivory towers.

All in all, sorry i didn’t realize i was commenting in a capitalist (liberal) community. I understand the nature of our disagreements to be your allegiance to the Nation State, Capital, and in general the established order of things in our society, the foundation of which (private property, authority, specialized labor…) you don’t seem to have a problem with. Given the nature of our profound disagreements, i don’t think there’s a way we can come to an understanding, but i’m happy to keep arguing for the sake of it if you so please.

[0] Except for parasite jobs of control, security, accounting and marketing which just exist for the sake of the capitalist system (and competition) but don’t produce any value overall.