First this:
http://dictionary.reference.com/search?q=fuzzy%20logic
Now I'll cut through all my BS. I'm sure you'll reply bullocks to this but all forms of human conceptual thought involves both elements of faith(assumption) and logic(truth). To assume that we think entirely through logic or believe entirely through faith is delusional, at least in it's practical use in the real world. You can not seperate the two from any human concept as nothing can totally be proven to make it complete logic nor disproved to make it a matter of complete faith.