# Section IX: Of the Effects of Other Relations and Other Habits explained — A Treatise of Human Nature > Chapter companion for A Treatise of Human Nature by David Hume. ## What happens Hume addresses an objection to his theory that belief is a lively idea related to a present impression. While resemblance and contiguity can enliven ideas, they are feeble and uncertain when alone. Causation, by contrast, provides a fixed and unalterable connection. Hume argues that belief arises only from causation, and that resemblance and contiguity only augment belief when they are conjoined with it. He illustrates this with examples of credulity, the weak belief in a future state, and the effect of seeing holy places on religious faith. ## Themes in this chapter ### Custom and General Rules Belief is derived from custom and habit, and the mind forms general rules based on experience, which can be overthrown by the want of resemblance. ### Association of Ideas The chapter explores the associative principles of resemblance, contiguity, and causation, and their differing effects on belief. ### Skepticism About the External World The discussion of how we form a system of realities from memory and senses, and another from judgment, touches on the nature of our beliefs about existence beyond immediate perception. ## Character check-ins ### David Hume The author, presenting and defending his theory of belief against a potential objection. ## Key lines > No weakness of human nature is more universal and conspicuous than what we commonly call Credulity, or a too easy faith in the testimony of others; and this weakness is also very naturally accounted for from the influence of resemblance. People are naturally too trusting of what others say, and this tendency can be explained by the way resemblance strengthens our beliefs. _Hume uses credulity as an example of how resemblance, when combined with causation, can fortify our reasoning._ > A future state is so far removed from our comprehension, and we have so obscure an idea of the manner, in which we shall exist after the dissolution of the body, that all the reasons we can invent, however strong in themselves, and however much assisted by education, are never able with slow imaginations to surmount this difficulty, or bestow a sufficient authority and force on the idea. Because we cannot clearly imagine what happens after death, it is hard to truly believe in a future state, no matter how strong the arguments or education we receive. _This illustrates how the lack of resemblance to present life weakens belief, even when custom and education support it._ > The lively idea of the places passes by an easy transition to the facts, which are supposed to have been related to them by contiguity, and increases the belief by increasing the vivacity of the conception. When pilgrims see the actual places where events are said to have happened, their belief in those events is strengthened because the vivid idea of the place makes the related facts more lively in their minds. _This is an example of how contiguity can augment belief when combined with causation._ ## Links - HTML: https://www.betterreads.online/discover/a_treatise_of_human_nature_se/chapters/section-ix-of-the-effects-of-other-relations-and-other-habits - Book: https://www.betterreads.online/discover/a_treatise_of_human_nature_se - All chapters: https://www.betterreads.online/discover/a_treatise_of_human_nature_se/chapters