Love when he ... [SPOILERS]

The point of the movie is that society is cold and uncaring towards those who are most vulnerable and, to a large extent, creates its own problems. There was also the subtext that the rich and privileged benefit at the expense of the regular joes like Arthur. Society is corrupt and evil, basically.

Having said that, I didn’t enjoy this scene because I thought I was supposed to, I enjoyed it because it resonated with me.

I think you can love what happens to those guys and cheer for Arthur in that particular moment. They savagely beat him, they were almost certainly going to do something horrible to that woman; this was a pattern of evil behaviour from them. When Arthur kills them, I think there's a cathartic release, an enjoyment in the comeuppance they get.

BUT, if somebody left the theatre thinking Arthur's worldview, thoughts, attitudes, actions, etc., were good or laudable, that's missing the point of the film. I also agree that Arthur's reaction to his murders is troubling and bad and an omen of the depths he's about to hit.

The movie (obviously) sets the viewer up to root for Arthur in that particular scene, sorta like you root for Charles Bronson in "Death Wish." Seriously, did anyone root for the three arrogant phukks?

Later on though you naturally question Arthur's killings, like the burly co-worker who simply stopped over to console him after his mother's death.

Anybody who physically attacks someone the way it happened in the movie had it coming if they get shot.

Yes, ideally, but he could easily have argued self defence. Which makes me wonder why he didn’t make such an argument when he was on Murray’s show.

No... that was self defense, the first two anyway.

The third guy, he hunted down... that was his first real delve into the Joker personae.

Great scene.
Like seeing Hannibal Lector suddenly unleash or something.

When he recovered his senses (after the first 2) and chased the guy out of the train, it was like, 'Oh man he just flipped'.

I'm wondering how much of that scene was true. After all, the whole thing was from Arthur's perspective and the movie shows he's an unreliable narrator. I think maybe the woman wasn't there after all, but he started antagonizing the guys for no reason, then shot them when they attacked him.

That's what makes this film interesting. It's like Inception - you're never sure what is real and what is just in his head.