If you really must engage in a discussion about whether or not HIV causes AIDS: the HIV/AIDS causality is established by meeting all Koch’s postulates: 1. Isolate and culture a pathogen from the patient. 2. Reintroduce the pathogen into another person. 3. Observe similar symptoms in that other person. 4. Isolate and culture a similar pathogen from this person.
This may seem not to be very ethical to do in humans, but it has happened. There have been several well-described cases of lab workers who have accidentally infected themselves with HIV and suffered the consequences. There are also models with simian immunodeficiency virus (SIV) and monkeys and the feline variant (FIV), all demonstrating the same causality, and all showing that the antiviral agents in question are highly effective.
To criticize the methods used in HIV research, is to criticize the scientific method in general. You must either be very ignorant, paid by some astroturfing organization, or an outright genius to have the confidence to do that.
Read more about Koch’s postulates here: http://en.wikipedia.org/wiki/Koch’s_postulates
