No one can say anything about cutting themselves unless they've actually done it. Seriously.
That argument doesn't hold up for anything; it's just a cheap cop-out to get out of a debate. Having an outside perspective does not preclude understanding of a subjective experience. It only precludes a complete understanding. But then, the person who experiences it themselves also loses out on what the outside perspective sees.
In a case like a psychological study the outside perspective has an advantage: Using interviews and other techniques it's possible to get a very clear picture of what the subjects feel and what common links they share with others like them, whereas that big picture is lost on others.
Not surprisingly this bogus brush-off is used for a lot of other addictions, too. "You can't know unless you've been there, man!" But you don't have to be an alcoholic to understand a lot about them, particularly if you've interacted with thousands. It's quite possible to have a thorough understanding of what motivates a junkie without being one; indeed, more possible.
It's a no-brainer that someone cutting themselves has a serious problem and needs help; the only person who needs to know what they're dealing with is the therapist.
Lummox JR
*slaps Hedgemissy* snap out of it! look at the pretty bunny...niiice bunny...