How we cite our quotes: All quotations are from On the Waterfront.
Quote #4
TERRY: You wanna hear my philosophy of life? Do it to him before he does it to you.
This is more tough guy shtick from Terry. He's stuck in a contradiction here: he feels like killing Joey was wrong, but Johnny "did it to him" (killed Joey) before Joey could snitch.
Quote #5
EDIE: Shouldn't everybody care about everybody else?
TERRY: Boy, what a fruitcake you are!
EDIE: I mean, isn't everybody a part of everybody else?
TERRY: And you really believe that drool?
Edie thinks we should care about each other because we're all interconnected, all a part of life. But Terry is still viewing us as all detached from each other—part of a dog-eat-dog world where everyone's looking out for number one.
Quote #6
CHARLEY: You're getting on. You're pushing thirty. You know, it's time to think about getting some ambition.
TERRY: I always figured I'd live a bit longer without it.
Barry's telling Terry he's got too options: he can keep following true morality, and testify against Johnny instead of trying to assassinate him. Or, he can take his gun, keep following the gangster's code, and get violent revenge on Johnny without actually correcting the bigger problem of the corrupt union dominating the longshoremen.