I think that I was asked in this section to go against what research shows: when people torture animals--and it's usually young people, not adults like Lenz--they are at high risk of going on to torture and kill human beings. They are, even after one torture and killing, pretty hopeless cases unless they get massive therapy along with the threat of, or actual, jail time. And after dozens of animals, acting-out all sorts of ghoulishly-imagined methods? The more animals, the more likely it is that they are a lost cause. And if they are still doing it, or just starting, like Lenz, by the time they are adults, this is probably even worse. This section is sort of manipulative to me, first, because it describes that Lenz goes through these dozens of grisly killings of animals, but goes into his exact thought process as he's drawing the line at killing people, as if he suddenly said to himself "I shudder to think". Our continuing in the text along with scenes that involve Lenz later, our being keen to see what he does in his life in other areas, his being a continuing viable character in the plot depend it seems to me, on us believing in this shudder-to-think moment, that he is "only" an animal torturer/killer, that he has the ability to hold himself back. And it implies that he feels remorse about doing the same thing to human beings.
Okay, so I may not be right about this part--maybe Wallace considered this section an illustration of the monster that drugs can make you and we're supposed to think that Lenz is not in control of his mind anymore (some psychotic people torture animals but it is most often sane people who do), but about the other manipulative part, the part that several posters found funny:
There is, of course, an acceptance of violence and cruelty in postmodernity; it has become so banal to us that the instances of it in art have to be made more and more shocking to get their point across. Many a (mostly) male character in pomo texts find release from his intolerable feelings of looking inward, and from the stress of life, through extreme violence. And a vital thing about the frustration-release is the character can't do something that's already been done, because then he'd just be a copycat--and he wouldn't feel any relief. Often in a text (or movie), the degree of violence he acts out has to be a quantum leap ahead of the violence that is already in the culture. This needs to be the case also to get people to read/view a work of fiction/film/theater as well. Their desires are sort of intertwined The character needs something shockingly new and different, and the reader needs something shockingly new and different. So worse and worse scenarios are created, not gentler and gentler ones.* And furthermore, we often aren't supposed to care about what they do in a moral sense any more than the characters themselves who do the evil deeds. This you can tell when the irony comes in. And sometimes we're supposed to be seduced by the supposed humor. It's just supposed to kind of vibrate in the reptilian primitive part of our brain and draw us in the way it draws the characters in, but without much judgement of the artist, because we're too busy laughing. I don't think that the section with the cat on fire chasing Lenz was funny at all, in fact I suddenly felt like I had an x-ray into the brain of an author trying very hard to make violence funny because he knew how well his outsized facility with words had cooked up something maybe more devastating than anyone before him. The cartoonish quality he was trying to make of that cat on fire scene. It's something that you would see in a (bad, pomo) cartoon only, not in reality, a cat being burned alive would not be able to do that kind of chasing, and that's the first thing I thought of when Wallace began describing this particular one of RL's animal victims, that nakedness and how he (Wallace) was suddenly exposed.
Fiction exists so we can learn to experience life as we never would otherwise, through the eyes of another person. Do I really want to experience what Lenz sees and hears and feels as he tortures and kills, down to every last detail?
*I had rather horrific, unbidden thoughts of the scenes under discussion when I tried to sleep last night, it's going to take me a while to go back to reading about Lenz.