Introductory Remarks -- What this section appears to me to be about:
The next part is on getting confused between "some" and "all." If you say you don't ride horses that means, for all X, if X is a horse then I don't ride it. If you say you do ride horses, that means, for some X, if X is a horse I [can] ride it. It is pertinent to the previous section since when I affirm that I eat mushrooms I affirm that I am willing to consume some kinds of fungi, but that does not mean that I am willing to consume all kinds of fungi.
If you speak of someone "loving the people," then not until people are loved in all instances may the person be regarded as loving the people. If you speak of someone "not loving the people," then we do not need to wait until he demonstrates a lack of love for all individual people. He fails to love the people universally because he does not love some one person. In the case of riding horses, then we do not need to wait until someone rides every individual horse to affirm that he rides horses. There is an instance of horseback riding because he has ridden at least one horse. With regard to not riding horses, we would have to see that the person fails to ride all individual horses before we could affirm that he does not ride horses at all. These are situations in which something either is or is not predicated universally.
• The connection to Mo Zi's doctrine of universal love is once again clearly apparent. It is also true that this section of the text has a bearing on the earlier part of the text because those sentences also involved making a distinction between, e.g., loving all physically attractive people and loving some physically attractive people who are also one's siblings.
• It is interesting that the author points out the importance of social context to the meaning of sentences. Structurally "loving the people" is no different from "riding the horses," but a strict criterian (and an impossible one) is imposed on the first, whereas a loose requirement is imposed on the second.