If one takes the position that we do not have enough evidence to come to a particular conclusion (as Lang did), then one takes that position with respect to the information available at a particular time. I don't know at what point Lang last stated such a position. Regardless, he's been dead for nearly 9 years.
AIDS is one of the most studied diseases in all of history; we learn more about it every year. It is certainly possible to state that we know HIV causes AIDS, without disagreeing with with Lang.
If one takes the position that we do not have enough evidence to come to a particular conclusion (as Lang did), then one takes that position with respect to the information available at a particular time. I don't know at what point Lang last stated such a position. Regardless, he's been dead for nearly 9 years.
AIDS is one of the most studied diseases in all of history; we learn more about it every year. It is certainly possible to state that we know HIV causes AIDS, without disagreeing with with Lang.