Three views

First,in Hume's view, concept is a part of human perception.In addition,Hume also divided human knowledge into two kinds: the relationship between ideas and practical things. Second,the certainty of causality we understand is actually a portrayal of our spiritual ability, and the continuous repetition of experience and habits is the reason for the formation of these abilities. Third,in Hume's discussion of the role of the mind, we can see that Hume's doubt is his doubt of the world outside the mind, but the purpose of his doubt is not to doubt itself, but to re inspire us to the world outside the mind.