"criterion" is a perfectly apt word.
criterion. noun. a principle or standard by which something may be judged or decided.
What principle or standard would you use to decide what is knowledge and what is not-knowledge?
Any process of binary classification (sorting things into two categories) requires a classification rule. This is the foundation of science. This is how null and alternative hypotheses are conjured and tested.
If I gave you a bag full of ААААААAAAAАААAAAАAAAАААAAAAAAAААAAAAA and I told you to sort it into two homogenous categories, you have to first be able to tell the difference between A and А before you can sort them.
Recognition is fundamental to epistemology. It's not a gambit - it's a fact.
Trivially demonstrable by showing you the METHOD for achieving the task: https://repl.it/repls/ImaginativeBlondCase