When something is proven, the world feels calm, just for a minute. Thinking loops stop and the structure survives pressure-testing. The reward is a moment of silence that I don't think most people need the way we need it. That's what we're chasing.
Now, look at what an adult life is made of. Relationships, careers, hobbies, our health, whether you're a decent person or not. All of it is permanently unsolved. Diffuse, if you will. There is no completion in sight. There's no moment where the decision to get married becomes an airtight case. You don't get a report card on your parenting abilities by some nebulous group that watches you 24/7.
So, I posit that INTPs build the best closure instrument they can find and then spend the rest of their adult lives somewhere that never closes anything.
I think this explains some things.
Start with introspection as an example. You can have beautiful internal documentation, and also have zero behavioral change. Introspection is seductive because it closes. You can run a mental loop on your own mind and find something you feel is true and verified in a half hour. Changing something is a butterfly effect that gives you no silence at the end. Ti takes the closure every time. The function is busy focusing on things it can close.
Most of my best work across twenty-odd years has been invisible by external metrics. The problem that didn't become anything, the design call that prevented a problem nobody ever thought about. Negative-space achievements. Things that didn't happen visibly for anyone but me. A thing that didn't happen also doesn't complete. Which means my internal record of what everyone else is doing wrong is easily seen and detailed while the record of what I'm actually good at can be invisible. I can tell you exactly how a company is going to fail months and months out. I cannot tell you whether I was any good this week at anything. Si is a fantastic archival database and a useless advocate. Total and absolute lossless fidelity, unless it's attached to your name.
Here's the point if you're still reading this absolute thesis of a thought:
A lot of folks here treat inferior Fe as a feelings problem. 'I'm bad at emotions and awkward in groups. I know that I should comfort someone but I'm not sure how how...' That's not the way I think it should be looked at for us. Ti, Ne, Si all source their verification, their...closure internally. You can check them yourself, you can close them yourself. Fe is the only function in the stack whose completion signal lives in another mind. You speak and then you wait. The answer comes from a source you have no visibility into or ability to audit or litigate.
Everyone lives with that, to be fair. For a Ti-dom, especially those who spent childhood being told they were wrong about things they were right about is external verification is enforced as untrustworthy. Ti became a hero because outside sources couldn't be trusted. Fe on the other hand, only runs on outside judgement.
The hero that saved you is holding the keys to the last locked room, and that's why Fe integration is so difficult for some of us. The first step is learning to be comfortable without closure. Do the thing. Do it often enough until it becomes something you can trust.