Comment by sciyoshi

Because I was curious about this: the use of "categorically" in the phrase "categorically false" doesn't directly relate to the concept of "categories" as groups or classes of things. Turns out it's actually related to the philosophical use of the term which originated with Aristotle and was further developed by Kant (see "categorical imperative" on Wikipedia).

"categorically" in this situation is used to emphasize the absolute, unambiguous, and unconditional nature of the falseness.