I have cats. Two to be precise. And both of them sit on paper. If it is important, than it will sat upon. Mail, bills, anything. But I must know. Why do they feel that it must be sat upon, rather than their $40 bed. Should I line their bed with paper? Please, tell me.
Our cats sit on paper all the time. Why? Who know? I have theories:
1.) Cats sit on paper that you’re reading because they want your attention.
2.) Cats sit on books to claim ownership
3.) The NancyButton explanation (I saw it on one of the NancyButtons, sold at SF cons): “Because cats read with their anuses”.
My cat likes to take paper and cover his food bowl with it. Not sure who he thinks he’s hiding it from.
Do you keep your papers close to some heat source (radiator, desk lamp, computer)? Or at some elevated place (shelf, bookcase)? Both are well known to be very cat-friendly environments.
You are asking for a rational explanation about cat behavior?
You must be a new cat [del]slave[/del] owner.
Cats do not like change. Cats are curious. Cats are territorial. Cats demand to be the center of the world. Paper makes noise. Paper has a tactile feel for cats. Paper must be subservient. Write all of this down, individually, on pieces of paper. Crumple each into a ball and drop them, one at a time in front of your cats. The cats will provide the answer you seek.
Trust me on this. I have nine (all indoor) cats, and almost as many feral (outdoor) cats.
Boy, did you ever pick the wrong username. 
Try using decoy paper—it really works. (For a more permanent solution, consider flypaper)
Leonard33; I have always found it a good idea not to question the foibles of our feline overlords. Failure to comply can result in far more distress for their slaves than merely sitting on paper…
Actually my username is a mashup of a name of our Alpha male cat. Sadly, he crossed the Rainbow Bridge in 2013. His ashes are in a carved box on the fireplace mantle. And periodically, one of his sisters sits on the floor in front of the fireplace at breakfast, looks up and cries. She speaks at no other time. I pick her up so her paw touches the box. She then wants to be placed back on the floor where she scampers off.
Besides attention, territory etc, cats seem attracted to paper. The tactile aspect seems pretty obvious and I wonder if as fur feels nice against our smooth skin, paper probably has a pleasing feel against their fur.
Cats like to be up high. Sitting on a piece of paper is incrementally higher than not sitting on the paper.
I’ll take door number 2.
The logical explanation is, that cats are the center of the world and know it. SO if you are sitting there staring at a piece of paper, then that has your attention, and since they are the center of the world and therefore the center of everyone’s attention, they need to place themselves in the center of your view.
Damn.
Sitting on paper gives one an area where you can see any insects trying to sneak up on you.
I always assumed it was because paper is a good insulator, so it’s warm to sit on. And to be annoying, of course.
I like that.
As a corollary to the paper issue, I’ve come to realize that all pens and pencils really do need to be on the floor.
One of my cats likes to sit on the newspaper I am reading. He also likes to sit on my keyboard when I am on the puter. And he loves to chew plastic. My female cat doesn’t really like to do likewise but she sees Wilson do it and does it too. However, I think she likes to chew on plastic. There was a prior thread on that, and, of course, nobody really knows, and they are not saying.
My cat never sits on what I’m reading.
Then again, he prefers Ivylad to me and I read off a Kindle while Ivylad reads books.
Cats are often attributed as being downright mean because they regularly sweep things onto the floor. In reality, cats are actually scientists and they constantly test the laws of gravity just to assure themselves when they might need it (escape from danger comes to mind).
Now if I could just get my herd to sweep the food crumbs onto the floor I would not need to clean the counters and the floor …