Fitting. Just a few minutes before reading that I had one of those "Contemplating your hands" epiphanies. I sat down in my computer chair, reached over to my mouse and came to a dead stop. A thought had brought itself to the foreground.

"I can't feel myself move."

Now when I say this I don't mean a numbness, or loss of the senses. But I couldn't discern what exactly I was doing that made my arm move. Or any other part of my body for that matter. That was silly of course, I move them all the time. So I tried moving them slowly, and felt a slight sensation.

Of course I thought; the slight sensation isn't really the feeling of moving my arm, it's the feeling of matter like air brushing against it. After all, I am basically sitting in a tank of atmosphere. Nerves report state, but aren't really projecting the feeling of movement.

That thought chain quickly led to a minor existential freakout. (During which I puzzled over the question of how the hell I move at all.)

I eventually generated three hypotheses:

1) The feeling of movement simply isn't reported by nerves. Introspection can't discern your cognitive processes, so why should it be able to your physical ones?

2) The feeling of movement is so faint that its overshadowed by the mere touch of air/one's own body hair. I know that when I'm in the deepest state of somnolence just before sleep; it's very often for me to realize I need to get up to do something, and struggle against the inhibitions on your movement somnolence induces before sleep. I can feel the struggle of this, it also feels the same if you try to fight sleep paralysis. One could argue that this is the feeling of movement.

3) You could argue that the feelings reported by nerves about the state of your environment are the feeling of movement. After all, feelings are just signals sent by nerves and interpreted by the brain. These feelings are generated by movement, and thus are indeed the feeling of movement.

4) My understanding of cognition is too incomplete to even hypothesize something remotely plausible.

Now, considering that so many articles on sleep studies mention them, I'm sure that the mechanics of how the brain controls the body are well understood and that if I'm truly curious I can google it. (Which is something I might just do.)

But the real reason I shared that anecdote, besides being semi-relevant to the topic at hand. Is because I took my ability to move for granted. In the same way that I take the idea that we could all be a simulation for granted. I've considered that a non-zero possibility for quite some time now.

I'll admit that I read some of the comments here before reading the story. (A big no no for science fiction, a genre that thrives on twists.) And after glancing at Tichy's comment, was afraid I might have spoiled it for myself. However, the journey is more important than the destination, so the concept of such a twist automatically made me go read the story. I was thoroughly disappointed with the ending.

The concept of a memory loop isn't really new. (I've seen it mostly explored in the context of time travel, but still.) But trapping a human in a text interface and presenting it as the thinking machine? Morbidly delicious. (In all the right ways.) And useful too. I could pull it out any time someone exhibits signs of having decided that a computer program can't be conscious simply by virtue of not being implemented on a human brain.

Having a human brain with no senses hooked up presented as a computer program would really drive home the message.

EDIT: Regarding the story, my immediate thought after finishing was questioning why if the program panicked because it lost all it's senses, why didn't he simply swap out the memories of J. Random. Person. With someone who already accepts that they might be a simulation. I'm sure that if they really believed that, it would be possible to calm them down by explaining that they are a simulation of themselves. And for bonus points, if someone were to consent to have their memories used for this (It isn't stated how he actually got the memories mind you.) that they would already have the possibility of being the simulation strongly in their head. And would eventually accept that they are a non-human.

Though, if you consent to something like this, you essentially ensure that you can never be sure weather your you or a replay of your memories. Though as it stands, you can't really determine this already. Which makes for one of those classic thought experiments that still has mileage.

Trains of thought down this road are probably inherently unresolvable, but still fun to try.