Bash "if" conditions unclear to me

I have a problem with bash conditions especially in "if" constructions. There is my example of if condition:

while [[ $BUT_O1 -eq false && $BUT_O2 -eq false && $BUT_O3 -eq false ]]
do
...
done

I need that cycle to stop when one of the variables comes true.

P.S. I read bash scripting how to but its still unclear for me. I even dont' understand why 0=true , when in the most languages 1=true.