According to a different source, this question refers to the chapters 16-20.
In these chapters, we learn about St. Clare and his opinions regarding the plantation and the slaves. We learn that, although he is a slave owner, he is undecided about his opinion regarding slaves. On the one hand, St. Clare sees the benefit of having slaves and is not particularly concerned with political or social matters. On the other hand, he is not convinced that the system is just or fair, and wonders whether it is morally wrong to be a part of it.
This ambivalence can be seen in at least two instances. The first one happens when St. Clare talks to his wife. While she is an ardent defendant of slavery, he argues that slavery only exists because someone needs to pick cotton. Another example occurs when St. Clare talks to Tom. Tom believes that St. Clare does not respect himself and should try to change his life. St. Clare takes his advice and respects his opinion, which is not always common among slaveowners.