Jump off cliffs and build your wings on the way down.
Acting without knowing takes you right off the cliff.
Science-fiction balances you on the cliff. Fantasy shoves you off.
Really knowing is good. Not knowing, or refusing to know, is bad, or amoral, at least. You can't act if you don't know. Acting without knowing takes you right off the cliff.
You've got to jump off cliffs all the time and build your wings on.