Greek statues that reveal the private parts are obviously not inappropriate as they were not intended to be sexualised. Same for some nudes which concentrate on praising the human body.
However, this cannot be said of all art with inappropriate parts. Eric Gill's art, for example. I'm not going to say what his art is like, but Google it if you dare... They are not intended to priase the human form or anything, but to shock. This type of art should certainly be censored.
In most museums, I think there are 18+ limits to exhibits that contain nudes. That isn't exactly censorship, but it's a good enough example that access to art should not be unrestricted.
See, what I think is that they should have certain museums that has art that isn't innoproprite, for children, and they should museums so that they can have this kind of art. I personally am an art lover myself, so I would not want the paintings and statues of old to be censored completely.
If a penis or vagina or breasts are in a piece, I don't see any reason to hide it. Our bodies are not "inappropriate." Art is a way of expression, and I personally feel it should not be censored. I don't think sexual pieces should be censored either, but maybe if it is too extreme...
As a child, my cousins and I found my grandparents' book of famous paintings and drawings, and we were giggling over the nudes. We asked grandma why they had a nasty book, and she replied that "It's not nasty when it's art."
It's an important distinction to make, and I never forgot it. And there is nothing inherently "nasty" about the human body.
Some art is meant to be disturbing, it's meant to shake you up a bit, make you think. Picasso's Guernica does this. So does Serrano's Piss Christ. You don't have to like it, but it should never be censored.
The only "art" I take issue with would be installations like Guillermo Vargas's starving dog. It was a living dog, not a picture or statue, and it died of starvation after the exhibition. The artist argued that no one who saw it intervened by feeding the dog, which does make a statement about Vargas and his audience, albiet a horrible one, but living, suffering creatures are not art supplies.
Still, stopping that wouldn't have been censorship, it would have been animal rescue.
I get really fired up (in an annoyed way) when someone starts complaining about a penis or vagina being immoral for people to show or see.
I think that people need to grow up and think for themselves and fight this illusion that has infected society that somehow a body part that is used for sex is now "inappropriate". What makes the arm different? Arms can be used to kill people, yet people are completely content with seeing the human arm, even though it can carry out an "immoral" act.
In conclusion, i believe that in general calling these body parts that i assume you are talking about are completely fine to see and not "inappropriate" in any way, and it should definetly not limit the creativity these great artists express to the world making the world a better place.
The book banners, and the usual suspects from the far right (John Ashcroft cough cough) who want to cover the bare breasts of statutes seem more concerned about their own lustful feelings than what the art is.
On all topics like this one, I leave you with "Piss Cross"
I believe it is a parent's role to ease a child into difficult subjects, not hide them from them. Also human anatomy is not intrinsically dangerous or immoral.
Moreover, if we are talking about violent or "adult" content, the same applies. It is a parent's responsibility to explain things to their children. Watching a violent movie or sexual content when young will not necessarily hurt a child. The lack of sensible adult guidance while discovering these more adult subjects will.