A negative claim is the opposite of an affirmative or positive claim. It asserts the non-existence or exclusion of something.[10]

Logicians and philosophers of logic reject the notion that it is intrinsically impossible to prove negative claims.[11][12][13][14][15][10][16][17] Philosophers Steven D. Hale and Stephen Law state that the phrase "you cannot prove a negative" is itself a negative claim that would not be true if it could be proven true.

https://en.wikipedia.org/wiki/Burden_of_proof_(philosophy)#Proving_a_negative