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EXISTENTIAL ANXIETY (or existential angst) is a term used to describe the anxiety and fear one feels when burdened with the responsibility of freedom. In his book 'The Concept of Anxiety' philosopher Soren Kierkegaard describes it as a "Dizziness of Freedom".
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So while freedom is a quality that many of us wish to have, for some of us the idea of being responsible for your own actions may be a daunting prospect as we live in such a cruel and indifferent society - because of this we try to shelter ourselves away from the truth of responsibility and all the hazards that the outside world has to offer.
"Man kind does not feel at home in this world, there is no safety in the world" - Paul Tillich, philosopher.
(Source(s)http://www.thefreedictionary.com/existentialism http://www2.webster.edu/~corbetre/philosophy/existentialism/whatis.html )