Inherited philosophical conclusions about the world, the self, causation, substance, the existence of God, the reality of miracles, and other topics cannot be defended on the basis of reasoning, says Hume, because such reasoning leaves us skeptical and perplexed. Hume's solution to such perplexity is to appeal to human nature. Human nature, illustrated in habit, custom, association of ideas, the propensity of the mind, inclination, the 'fancy,' and other nonrational forces recover and preserve for us those things intellectual power cannot support. A use of such nonrational forces is fideism which Hume received from thinkers like Bayle and introduced into English-speaking philosophy. His fideism was applied to both religious and metaphysical issues.