Assuredly McCain isn't comfortable talking about this -- and the McCain campaign discouraged me from writing about this -- but the reason the aged Arizonan doesn't use a computer or send email is because of his war wounds.
I realize some of the nastier liberals in the blogosphere will see this as McCain once again "playing the POW card," but it's simply a fact: typing on a regular keyboard for any sustained period of time bothers McCain physically.
He can type, he occasionally does type, but in general the injuries he sustained as a POW -- ones that make it impossible for him to raise his arms high enough to comb his hair -- mean that small tasks make his shoulders ache, so he tries to avoid any repetitive exercise.
Again, it's not that he can't type, he just by habit avoids when he can repetitive exercise involving his arms. He does if he has to, as with handshaking or autographs.
It's certainly possible that the Obama campaign did not know this, since McCain makes it sound in interviews as if this is a matter of choice, not discomfort because of his war wounds.
"I read my e-mails, but I don't write any," McCain told Fortune Magazine in 2006. "I'm a Neanderthal - I don't even type. I do have rudimentary capabilities to call up some websites, like the New York Times online, that sort of stuff. No laptop. No PalmPilot. I prefer my schedule on notecards, which I keep in my jacket pocket."
