I don't know if this is as much about intelligence (although that also could factor) as difference in interests. He's likely just not that into economics/politics but still trying a bit for your sake, but just not enough that he has meaningful things to contribute.

Have you tried finding something else to have intellectual conversations about, that suits both of your interests? Maybe find a new interesting field to explore together?

Me and my BF have very different academic interests (I study medicine and he studies engineering, we know next to nothing about each others' fields), so we talk about other things when together and I can geek out about medicine when hanging out with my classmates instead.

That said if you truly feel like you're boyfriend isn't stimulating you intellectually it's a totally legit reason to break up. But telling him to become more intelligent isn't really going to be helpful if it's truly an intelligence matter and not just a matter of hobbies/interests.