> He thought that there was this big list of moral codes [list of rules that gets progressively sussier]

This isn't true. There's only three or four formulations of the CI depending on your interpretation.

>He uses the example of someone with a family opening the door after getting a knock. Standing there is a psycho axe murderer who asks him where his family is. Now the question is, should he lie? Well I think most people would say yes.

Beside the point for Kant interpretation but why should I think the fact that most people would say you should do something as good evidence for doing it? People get moral judgments wrong all the time, especially when you introduce features that test their rational consistency.

>While lying is usually wrong, doing it to save your family is ultimately good. But Kant would disagree. He says that if you were to lie and say they're not home, the psycho axe murderer would disappointedly turn around and walk away, thinking about how he's an embarrassment to his psycho axe murderer ancestors when all of a sudden, he sees your family climbing out of the window. Turns out they overheard the conversation and decided to escape, but if the guy had just told him the truth that they were in fact home, they would've had a chance to escape. Now, I've been keeping a veneer of objectivity in this video so far, but I've gotta say this is one of the dumbest ideas in philosophy I've ever heard.

Kant definitely doesn't say anything like this, and you haven't even attempted an explanation of why Kant thinks lying is morally wrong. Even if you disagree with Kant's reasons for thinking lying is morally wrong, he never claims that the axe murderer will act in this way.

> I mean, leaving aside that he's totally taking for granted that the family would overhear the killer and try to escape through a window that's conveniently in his line of sight, you're tellin' me if a billion people were strapped to a conveyer belt being dragged to the pits of Hell, and you can stop it all by slapping a kitten, he'd be like 'nah bruh it's still fucked up like you can't justify slapping a kitten over anything durrr"

Kant famously doesn't think animals are owed anything and that the value of people is always superior to the value of things (e.g. cats), and thus he would never say this.

Given the above, I think you could really benefit from sitting down and reading Kant. More generally, if you find yourself saying something like "This extremely influential and well-respected philosopher is obviously wrong", the principle of charity would suggest you probably misunderstood them.