If a "blind spot" is understood literally then to have no blind spots would require to see, well, everything there is to see at the same time, which is sorta impossible. I think it's pretty obvious that our ability to think - to take facts into account and work out their consequences - is necessarily very much limited by a finite input bandwidth, a finite storage capacity and a finite processing capacity, and so any finite brain will have mental blind spots. To believe otherwise is to be a great believer indeed, IMO...