After many years of observation, I've figured out something about cats. Cats are very smart animals, but they seem to have a fundamental problem with the concept of physical space.
Here's how its goes: The cat wants out. She's at the back door, carrying on about how the door is closed... "Why won't it open? Why is there no cat flap? Where is a person to open it? Who left this door closed? Why does my house even have doors?" ...and so on. So I go and open the door, happy to have some peace and quiet.
Then I hear the cat come in through the cat flap (the one in the laundry that is just around the corner from the back door, and leads to the back yard). She then pads down the hallway to the front door and starts howling. "Why is this door not open?" she cries. "We discussed doors! You agreed to leave them all open for me! This is not good enough! Open the door at once!"
So I open the door, and watch the cat dart outside and run off around the house. I walk through the house and peer out the French doors. What do I see? The cat, looking disconcerted that there's nothing exciting happening in the other back yard.
You see, to a cat there's the back yard reached from the back door, and the back yard reached by going out the front door and around the side of the house. Now, I ascribe intelligence to an animal that figures out what door handles are for and can happily break into a room previously thought secure from feline invasion. But when I see an otherwise intelligent animal acting like the front and back doors are portals to alternate dimensions, I start to consider the possibility that they have a little trouble with spatial awareness.
Typically the cat then comes back into the house via an all-purpose dimensional escape device known as the Controlled Animal Teleportation Feline Location Access Portal (CATFLAP for short). Then she comes up to the French doors and start howling for them to be opened - perhaps the third back yard will have birds in it!
Maybe their tiny kitty brains don't have particularly developed spatial functions - though this is hard to believe when they clearly know the shortest route from their current location to the fridge door they just heard opening. I think the problem is that they just don't get that the doors all lead to the same place. "Inside and Outside" is hardly a concept that a cat needs to survive in the wild, so they're just not capable of understanding it.
I wish they would, though. I'm getting tired of having to open each door in turn in the space of half an hour. But for cats, it's clearly easier to perfect the art of manipulating humans than it is to learn that the front and back doors ultimately lead to the same back yard.