What changes occur in Tom's attitudes toward others?

This really depends on at what point in the story you wish to refer to. Still if I was to choose a dynamic moment for Tom, I would say when Casey is murdered. It is here that Tom sees that he must fight. He can no longer drift hoping for better times. Tom realizes that the plight of poor men won't change as long as they are decided and conquered by big business. Tom knows he has to try to Cary on Casey's vision of union and brotherhood against big money.