This neat cartoon hints at the helpful point that knowledge of scientific failure is still scientific knowledge.
If the foundation of knowledge is causality, as Aristotle affirmed,1 then knowledge that A doesn’t cause C is as important as knowledge that B does.
1. “…we have knowledge of a thing only when we have grasped its cause” (Posterior Analytics, 71 b 9–11. & 94 a 20) and
“…we do not have knowledge of a thing until we have grasped its why, that is to say, its cause." (Physics 194 b 17–20)