Weak agnosticism makes the uncontroversial claim that a person may claim to personally have no knowledge of gods. Strong agnosticism, however, goes considerably further by claiming that knowledge of gods is impossible to acquire.
"One interesting criticism of this strong agnosticism is that for a person to adopt the position that knowledge of gods is impossible, they essentially concede that they know something about gods — not to mention the nature of reality itself. This, then, would suggest that strong agnosticism is self-refuting and untenable."
Well how about that.