Knowledge and credulity
All belief is credulity.
The only valid stages of knowledge are uncertainty, certainty and the transitional stage of inclination.
If one knows then one is certain. This can only come about through direct personal experience.
If one does not know then one is uncertain. However, in this state one may be inclined towards a particular view or possibility of truth. Then one continues to pursue and investigate that until it becomes certainly true through direct knowledge of its truth, or it becomes certainly untrue.
While in the transitional state of inclination, one is giving greater weight to the possibility towards which one is inclined. Then the only valid course of action is to follow the advice and example of those who are certain of that possibility. They provide the guidance that may lead to knowledge.
But one has to arrive at certainty through one’s own experience of truth. One cannot have certainty through reports of the certainty of others. That is only belief, and is always the product of credulity.