Scottie I have a mastiff type dog and he mos def is to stupid to be afraid, he plays with bulls.
But size isn't everything, not even aggressivness or dominance. I have been to a few temprament tests for dogs concerning bears. If you would pick your dog based on who looks the toughest on the parking lot and barks the loudest against the other dogs you might not acctually pick the one who,d stare down a bear. Some real alpha dogs loss themselves when they come face to face with a bear, even id there is a fence between them
The breed I see with the most dogs that pass %-wise is the jagdterrier