There is a land where every inhabitant is either a day-knight or a night-knight. Day-knights tell the truth in the day and lie at night. Night-knights lie in the day and tell the truth at night. One inhabitant once said, "It is day." Is the inhabitant a day-knight or a night-knight?

4 cases

1 he is a day knight and it is day - he would say it is day.
2 he is a day knight and it is night - he would say it is day
3 he is a night knight and it is day - he would say it is night
4 he is a night-knight and it is night - he would say it is night.

So he must be a day-knight!

Posted by Kenny M on 2011-03-08 21:25:39