There are two "models" I've used to understand SM and SM desire throughout my life.
The first I remember most vividly when I called the urgent care line at my university. I'd been having serious trouble coming to terms with my desires, and had seriously self-harmed for the first time. I remember calling the helpline and talking to a young woman, probably a student. I confessed my desires and my shame and the fact that I'd cut myself out of shame. I can't remember if I begged her to help me change. Maybe I did. I remember staring at my half-drunk smoothie on my desk as it melted, feeling like I was in some weird dream.
She had no idea how to deal with me. I can't recall if I asked for an actual psychiatrist or if I just called back the next night. But the same thing happened, the crying confession, and suddenly the voice on the other end of the line said words that changed my whole life.
"Don't you realize that among people who have gone through serious trauma like you have, sadomasochistic sexual fantasies are common?"
Common? It rocked my universe. I wasn't weird at all. (It almost made me sad. Took away this feeling I had that I was one of the few, the marked, the profoundly perverted.) I was just damaged, just responding to things that had happened to me. In a way that was not only understandable, but sensible and perhaps even sane.
Those words changed my life. I don't know if I'd be here if they hadn't given me an anchor, a way to believe that I wasn't cursed or doomed or rotten, crazy, fundamentally wrong inside.
And that is one model. The trauma model. This model says something like: Sadomasochism is a response to trauma.
On this model, it's a coping device, essentially. People develop fixations with pain and with traumatic experiences involving power (say, abuse), perhaps because the experience of it is intense, perhaps because it leaves psychic scars. But people feel compulsions to act out or to re-live their trauma. Sadomasochistic fantasy is an attempt to do this, in order to regain control that we had torn from us.
This model is okay, so far as it goes. It offers us a chance to be something other than twisted, insane, incomprehensible. But it still leaves us with something odd and unacceptable, to my mind.
That is that if we still have these interests or fantasies many years after the initial event, this indicates that we have not adequately processed the trauma. I was told many times that my fantasies "might" go away, or lessen in intensity, once I had dealt with the underlying issue. It led to many bouts of guilt when my fantasies were particularly strong or particularly violent, and to paralyzing fear that I had backslid on some scale of Survivor's Progress.
And it led to people like my parents believing that someday I'd be cured of SM, and asking me why oh why oh why I remained obsessed with the things that had happened to me and telling me of their great hope that someday I would no longer be fascinated with pain.
I don't believe the trauma had no effect on me. I actually suspect that the fact that my strongest fantasies involve knives and blood have more than a little to do with being cut open. However, as I'll make clearer in a moment, I don't subscribe to this model, and I don't feel at all sure I wouldn't have developed other sadomasochistic interests if I hadn't been.
The second model is an orientational model. This is the theory that, at least for some people, SM desires simply are what they are, a facet of the person, like being straight or being gay. Like those, we don't know quite what causes them. Unlike those, we don't have (at least that I know of) any interesting research suggesting a biological basis or link or influence.
This is what we get -- or what I get, really, as I don't want to speak for others, least of all for researchers -- when I look around and see the people who tied themselves up at age 8, and don't really remember any abuse, thanks. The people who would try to finagle their friends into bossing them around, and fuss and fume when the toppy-tots they recruited were too kind. The people who were never spanked, but who would see the family across the street punishing the kids and feel all tingly and wonder when it was their turn. The folks who tied up their teddy bears.
I don't think any other model makes sense, really. Even the most committed Freudian who felt sure the trauma model applied to me squirmed when I asked him "Can I change?" and said something about how it depended how firmly rooted my response to those formative experiences were.
His answer was the answer I knew perfectly well myself, but he couldn't say out loud, because to him it was a sentence of perpetual brokenness or abnormality: If you have to ask, the answer's "no."
It's possible for the two models to be complementary: This is your orientation, and you have it precisely because of past trauma.
But the thing is: if orientation is orientation, why care where it comes from? Think of the conservatives scrambling to get people into reparative therapy for homosexuality. It matters where this comes from because if it is a mental health problem, one common mode of talk therapy is to work through past issues. It matters because what they've got is a model like the trauma model: work your issues with Mo or Dad out and the gay will go poof.
But if gayness is an orientation, where it comes from is an interesting question, but not a vital one. Humanity is diverse, and that's that. If it's biology, well, so are a lot of things, from eye color to handedness. We stop caring why, because why is not the important question.
And that's the thing that many haven't gotten to yet with SM. Even when people do respect us, there's this idea that asking why is appropriate. It's the sort of thing for which a reason is needed, whether it be trauma or being spanked as a child or the influence of patriarchy or any number of other odd theories people come up with.
When people ask me why and I say "I neither know nor care," particularly in certain feminist circles, this is taken to be "compartmentalizing" a part of my life and not exposing it to useful or necessary scrutiny. But if I asked these women (as the case may be) "why are you straight?" or "why are you queer?" the answer, I'd bet, would not be a thoughtful discussion of social factors. A truly committed "radical" might admit some of it is socially constructed, but for most people, in the end, the answer is "I am."
And that's my answer, too. I am because I am. I don't have to know why, because it's the wrong question in the first place.