Laura claims that Harold is lonely. She argues — this is her main point or conclusion — that Harold should sell his cabin and move into town. She makes this claim because she thinks that, if Harold moves into town, he will not be lonely anymore, because he will be near other people all the time. Ralph responds by pointing out that living in towns alone doesn't necessarily make people less lonely. He says that to ward off loneliness, it's not enough just to have proximity to others — you also need genuine interaction with them.

Ralph doesn't necessarily disagree with Laura's central recommendation that Harold should move into town. Ralph just qualifies some of the reasoning Laura uses to get there. Specifically, he calls into question Laura's belief that once in town, Harold will no longer be lonely because he will now have other people around him.

Ralph suggests that while proximity to others might be necessary — notice that he says that what is needed to avoid loneliness is "not only" proximity to others — it's not sufficient on its own to ward off loneliness. Genuine interaction with others is also necessary. So even if Ralph still thinks Harold should move into town, which is possible, it's clear that he doesn't think moving into town alone will solve Harold's loneliness, as Laura seems to think.