What a man hears he may doubt.
What a man sees he may possibly doubt, but
What a man does, he may not doubt.
"Can" is a simple matter of ability. Whether the doubt itself is emblazoned with integrity, or not, does not matter. If you were to change that to "What a man does, he may not doubt.", then you'd be presenting a matter of conjecture (methinks) and raising up a Campaign Against Thought Police! :-7 (tongue in cheek emoticon) --Grant----
Good point...Changed...What I am aiming at is covert action by Powers That Be...Asking them to be upfront about their actions. Can't say more:-).