The hedgehog’s dilemma, or sometimes the porcupine dilemma, is an analogy about the challenges of human intimacy. It describes a situation in which a group of hedgehogs all seek to become close to one another in order to share heat during cold weather. They must remain apart, however, as they cannot avoid hurting one another with their sharp spines. Though they all share the intention of a close reciprocal relationship, this may not occur for reasons they cannot avoid.
Both Arthur Schopenhauer and Sigmund Freud have used this situation to describe what they feel is the state of individual in relation to others in society. The hedgehog’s dilemma suggests that despite goodwill, human intimacy cannot occur without substantial mutual harm, and what results is cautious behavior and weak relationships. With the hedgehog’s dilemma, one is recommended to use moderation in affairs with others both because of self-interest, as well as out of consideration for others. The hedgehog’s dilemma is used to justify or explain introversion and isolationism.
(Hedgehog’s dilemma is also an episode from NGE, a wonderful anime that I still haven’t finished. Shame.)