Rectification of Names
The rectification of names is the belief that depending on your title, there are duties you must fulfill and limits to what you can do.
Many people in Kung Fu Panda 2 have titles. Po is the dragon warrior, Master Shifu is the master, and Lord Shen is a prince and forcibly becomes the emperor as well. There're expectations for all of them and they all must fulfill their duties. There're also things they can't do as well. And Shen abused his power and hurt his people which ultimately caused his downfall. Po's duty is to save China from all threats, and he does defeat Shen and his weapons. He knows that this is his duty and he does his best to do his job. In Kung Fu Panda 2, everyone has a job and it's made intricately clear that everyone must do this job in order to have a harmonious world. Bad examples such as Lord Shen show what happens when you do what you shouldn't according to your job(Lord Shen is an emperor so he should be looking to past emperors and mimic their actions, but he decides to go off on his own and start creating weapons). Lord Shen also went against his parents' wishes and continued to do what he wanted despite them thinking that it was a bad idea. As a result, he nearly destroys China. And good examples such as Po who always saves the world and gets showered in love for it. His father the goose is also a good father for he always makes Po happy, makes him a home to go back to, and worries about him a lot. As he says "I'm his father! I'm always worrying about him", and because he's a good father, Po always comes back to him safe and sound. So, Kung Fu Panda 2 teaches the importance of doing what you must do depending on your title, whether it be emperor, dragon warrior, son or father, and the importance of never breaking taboos of your title.
P'u the Uncarved Block
The uncarved block repesents how humans are in their purest form, simple and unique. Every time we're bound by rules, we've been slowly carved into something that we're not. But the natural form we were born in is the form that allows for true wisdom and morality.
Po can be considered an uncarved block. He's seen as foolish by many and he trusts in the Dao to guide him and the world to peace. Lord Shen, in conversation with the soothsayer, says "Your magic panda is a clearly a fool". To which the wise soothsayer replies "Are you sure he's the fool?". Another example of when Po was foolish was when his hand was on fire and instead of putting it out witht he water of the sea that he was in, he shoved it into his own mouth. Not the best move he could've made. He also shows his childishness when he never questioned that the goose was his father. The goose is, but not biologically because it seems impossible for a goose to birth a panda. But according to Daoist values, Po is wise because he's a fool. Po is childish and simple which makes him the perfect daoist, the uncarved block.