Causal Condition

One attempt is that of Alvin Goldman, who puts forth a theory of causal connection between knowledge of propositions. Goldman states that persons A knows that X if and only if the fact X is causally connected in an ``appropriate'' way with A's believing that X. What he defines as appropriate is a combination of perception, memory, and a causal chain of events that is correctly constructed through warranted inferences.

In other words, for someone to know something, it must be related to something else that such a person knew in a certain way. This seems quite vague and broad blanketed. Hence the reason why Goldman's condition does not appear to solve the perceptual Gettier-type problem illustrated above with Mrs. Knull.