My logic is very rusty, I have given it a shot below, but not sure if it is correct. feedback appreciated!

"Either all cognition is cognition of appearance, in which case there can be no cognition of noumena, or there can be cognition of the noumenon, in which case cognition is not essentially cognition of appearance"

P- all cognition is of appearance.
Q- cognition of noumenon.

P ⋁ Q
P→ -Q
Q→ -P