Abstract
Insanity is identified with irrationality, while rationality is considered to be the mark of sanity. Yet we want to say that rationality could be the cause of insanity. We can see a subtle kind of insanity inherent in an institution believed to be highly rational. Rationality in an ideological belief also turns into rational insanity when the ideology itself works for the interest of the advantaged as a tool of deception. We believe in the rationality of open communication. We believe that information technology has given us the most rational means for open communication. The Internet revolution or Internet democracy is expected to become the most rational means for the institutional goal of democracy. However the rationality of Internet communication has demonstrated a serious tendency to cause Internet insanity. We have been proud of being 'rational animals'. But now we are concerned because 'rational animal' could mean 'rational but animal-like' or 'rational but impulsive', which in turn could mean 'rational but violent' or 'rational but mad and insane'. Perhaps it is time for us to think seriously about the possibility of mass insanity through rational insanity, and seek the way beyond such rational insanity.