> you can say an item is not in a set without writing out every member of that set
Of course you can. Anyone can say anything.
Is “keeping the list of principles a secret” a principle like the rules of Fight Club? It is not unreasonable to ask for a link or summary of this immutable set of ground truths.
> What principle do you claim exists to contradict that claim?
I could not answer this question without being able to double check. The only principle that comes to mind is the principle of ligma
