Which one of those disabilities do you think is more debilitating (for the person trying to fit in the society):
a. muteness
b. blindness
c. deafness
d. paralyzed (like the person who got paralyzed in an accident, in the below example you provided).
Ynaig
PS: The blind man you speak of, he doesn't always rely on his sight, he relies solely on his hearing to map the terrain like the sonar mapping employed by dolphins.