After blindfolding them, Paul picks up the five red discs, sticks one on the forehead of each logician, and hides the other discs elsewhere. After removing the blindfolds, everyone sees the discs (all red) on the others' foreheads but not the one on his own.

After a few minutes, one of the logicians (that reasons a little faster than the others) correctly states the color of his disc. How does he work it out?

ok totally got it. I was close but wrong on my first guess, and haruki was close but i think he missed it too.

paul did remove all the blindfolds. But it says everyone see's the discs. So everyone see's all the disc, so its easy to says its red becuase they see all of them (including their own) Then it joshfully reminds us (their all red, and that all the logicians can see all the red).

Because this line 'but not the one on his own' refers to Paul.

Paul is the hidden pronoun or whatever of 'after removing' --> who removed? paul removed. so therefore 'not the one on his own' refers indirectly to paul. paul cant see the disc on his own head becuase he never put one there!!!

thats gotta be it!