Here is a passage from the Analects that seems to me to defy many of the interpretations of the relationship between ren (humanity…?) and li (ritual). 15.33 reads:
The master said: ‘If one who reaches knowledge is unable to guard ren; even if this person attains it, they necessarily lose it. If one who reaches knowledge is able to guard ren, but does not skillfully manage the people, then the people will not be reverent. If one who reaches knowledge is able to guard ren, skillfully manages the people, but in motivating them does not use li, this person has not yet done the right thing. ‘ (translation is my own)
This seems to go against the interpretation of the ren/li relationship which holds that making one’s actions accord with li is the very definition of what it is to be ren. After all, the end of this passage considers a person who is able to “guard ren” but not “use li“. Surely if to be ren is to act in accordance with li then the above would not be possible (unless “guard” [shou] does not entail “has”–which would be odd, I think).
At the same time, this passage looks like it is opposed to the interpretation of the ren/li relationship which holds that li is a way to enhance ren, the natural “human-heartedness” that a person might cultivate. In 15.33, we have ren discussed the same way in all three sections–it seems not to change. However, the person who has ren can change, and be a better or worse person, depending on what other “virtues” the person has. It looks like this passage might help to support a view of ren as a “non-major” contributing virtue for Confucius. Might it not be that ren is not a supreme virtue, but simply a necessary condition for being a junzi, although one Confucius concentrates on more than, say, yi (“righteousness”…?) or zhi (“knowledge”), because, perhaps, he finds ren more lacking in his students and the society at large than most of the other virtues?
For example, if I were teaching a bunch of lazy students, I might emphasize hard work more than other virtues, in my descriptions of the ideal person. This would not be because being hard-working is more important a virtue than, say, honesty, but rather because all of my students are honest, but most of them are lazy, so I decide they need no help with honesty, and great help with their laziness. I think something like this may be what is going on with ren, which may be part of the reason it is notoriously hard to crack.