(Written for some folks on facebook.)
What does it even mean? Well, to objectify someone is to treat them as an object, rather than a subject. A subject has the capacity for subjective values, preferences, emotions, and beliefs that matter; an object does not.
In this culture, men are most frequently objectified as sources of money and (particularly in Mormonism) decision makers. This happens when men are expected to financially support and "preside over" a family without any regard to their actual preferences. It also happens when their ability to make money is considered the most important or only important thing about them. When this happens, a man might as well be a money making robot--or an ATM. An object.
Correspondingly, women are most frequently objectified as providers of sexual pleasure. Women's bodies are routinely described as the most important or only important part of them.
So what's wrong with that? I'm not going to pretend to be arbiter of objective morality. My problem with you objectifying women is that it makes me uncomfortable. Very likely, it makes other people uncomfortable too. From my perspective, there are three possible explanations for your behavior:
1. You don't realize that it bothers people
2. You are aware, but you feel that it has benefits which outweigh the discomfort it causes
3. You are aware, and you're just a jerk
I'm hoping/guessing it's number one.
One reason it bothers me is that I don't really understand why you're doing it. Let's say you post in a facebook group that you are only attracted to slender, blond (white), tanned women with great muscle definition, stunning faces, and b or c-cup breasts. After the first 45 seconds of feeling sorry for you--since you're clearly unable to experience the pleasure I do when viewing a much wider variety of bodies--I start wondering why you've told me this. If this just came up once in awhile, I'd think to myself, "Whatever. I guess he needs to out himself as an anorexiabarbiephile. Sometimes we all just have that kind of day; poor kid must need a hug." However, it seems like there are guys who feel the need to talk about this almost constantly, and it seems to extend significantly beyond simply sharing "this is the kind of body I'm sexually attracted to."
The case-by-case standard which I prefer to use when deciding whether to sexually objectify someone or not is this: What would the person who that body belongs to (subjectively) prefer? When I sit there and stare at my boyfriend's ass/arms/shoulders/face/whatever, thinking nothing whatever about his sexy brain, I can be fairly certain that his sexy brain is down with that. When you sit there talking about whether the sister missionaries on temple square are "doable" or not, I can be fairly certain they would not be down with that. And so can you.
"But wait!" you say. "We aren't actually doing anything. We're just talking, many miles at a distance. This doesn't impact them at all."
And the answer to that is. . . well. . . sort of. Because when you talk in this way--when you go on about who is hot and who isn't and which body parts should look like what--when you are so obviously willing to ignore the preferences of both the women you're talking about and the women who are in the room with you--you leave me with the impression that you are used to sizing up every woman you meet as a sexual object, and that her functionality as a sexual object is often more important to you than her subjective preferences.
I feel threatened by this. Objects are vulnerable. If an object doesn't live up to your needs and expectations, you can do pretty much whatever you want with it, and that's just fine. I have a friend, for instance, who takes great joy in smashing his old crockery pieces against a cement wall. At the very least, you're likely to discard objects that aren't satisfying. I feel threatened because there's absolutely no way that I'll be an adequate sexual object* in your world. It's like loosing a contest I never wanted to enter before I'm allowed to talk to you. If I had to pass the "are you a good sexual object?" test before you ever get around to considering my other qualities, you would never even see me as a human being.
And I feel frustrated because there's no place for me in that conversation. Since I'm not interested in objectifying others with you, and I'm not interested in being objectified, that leaves me. . . not interested. It leaves me on the sidelines, worrying about what the takeaway message is for the younger and less confident women in the room, and whether this is a healthy place for them to be.
I get that you, rightly, don't want to be demonized for having a sexual interest in bodies. I get that you are almost certainly not ever going to do any physical harm to me. I sympathize deeply with your desire to bring some freedom and openness to your sexuality. I just think there are better ways to do that.
*Ironically, while it is objectively/statistically the case that the average college dude would rather date a skinny heroin addict than me, focusing on the ideal female body is likely to make any woman--even a woman who actually does look like a supermodel--feel inadequate. Or at least, that's what this book told me.