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?

"...each logician must know for certain that every other logician has already worked out the reasoning for the previous step, in order to advance to the next."

I disagree with you, Avin. The conclusion of the faster one became to the fact that all the others 4 would answer first if they were seeing a blue or a green disc.

If we could conceive that all the five logicians reason at the same speed, they all would conclude his colour at the same time.

And to TKC: itīs better working with "hats" than with "discs"?  j/k... "long tedious"? I donīt think so. Great work.