Some isms are dependent on others. For example, science is dependent on the truth of mathematics (plus other assumptions). Therefore the scientific ism is a shell which goes around the shell of the mathematical ism.
Shell 0 - no assumptions about the universe. Is this even possible?
Shell 1 - logic
Shell 2 - existence. I think, therefore I am.
Shell 3 - truth exists. There is some state to the universe. Perhaps unknowable by humans.
Shell N - shell normal. This is the shell from which a person N1 lives his/her life.