Many times when someone tells us something we just accept it. We don't consider the question "whether it is true". Perhaps because we trust the speaker. In such cases:
We believe others _____ .
Our acceptance of what other tell us is ______ .
unreflectively/unreflective? non-reflectively/non-reflective? non-speculatively/non-speculative? Immediately/immediately.
"uncritically" sounds to me too strong for such cases.