mastercracker is right, from my personal point of view i think there is no doubt that some form of damage is done from cracking. i think the debate is how much, if its tiny and as such insignificant then thats what it is, if its major i could believe that too. i also think the type of joint and also which joint it is makes a massive difference to the relative damage it causes.
what you shouldnt be doing is saying that there is a definite link as if you are an authoritative source, like youre a doctor or something. people come here with questions and they might get the wrong idea about your status and take what you say as fact, and for that reason you shouldnt state it as fact. they dont know that you are just a 14 year old kid. i use the word just, not as an insult to your age, but because youre a "just" a person with an opinion, with no actual deep knowledge of the issue.
dont take what he or i say harshly, i just think its best to point to the evidence and let others conclude rather than conclude it for them