I don't think AJ was dumb, dumbness implies some cognitive disability. AJ wasn't stupid, he was just ignorant. Like most kids the age he was portraying. If anything he just came off as totally ambivalent about everything and as he grew up the ambivalence lent itself to a life of lacking an identity and academic skills, which hampered his work prospects as an adult; that identity crisis was further aggravated by his perceptions of being incapable of living up to his father's legacy - Being neither physically imposing nor mentally imposing - I don't think this was ever outright said, but I think it was strongly implied; especially in the season where they wanted to send AJ to that military reform school. if anything AJ was the epitome of mediocrity in a family of people that excelled at their respective paths. AJ excelled at... Not excelling, but that was the role he carved out for himself in his family because his parents did not know how to raise a child that was not independent early on in life. Despite her college education Carmella was not what I would call a forward thinking mother who tried to engage her children on any intellectual level, only at their archetypal roles.
the problem is Tony loves his children, he was a caring father but he wasn't a good father, he couldn't teach or direct his children, what wisdom did he really have to impart? His life was one of taking the road of least resistance (for the Soprano family). Tony always looked for his father in himself and in turn, looked for himself in AJ. Ironically, Tony always seemed to think of himself as being inadequate next to Johnny Boy, and with Tony's hamfisted fathering, AJ seemed to have similar feelings of inadequacy when he measures himself up against Tony.
Paulie and Chrissy are both kind of idiots. Chrissy you can more easily explain away given what we know of his childhood and how he was raised steeped in mafia ethos and the mythology of Dickie Moltisanti. being a junky most of his life probably didn't help much either. Paulie may actually just be mildly retarded. remember when Tony suggested he get tested for autism?
