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All three people you mentioned may have used the word libertarian, but all of them if you read anything about them start with "anarchno-capitalist," not libertarian.
In 1789 , the US Constitution created a limited federal government where its powers were specifically enumerated .
In 2013 we have a behemoth welfare/warfare state where the government routinely ignores our rights.
Versus
Anarcho-capitalism (also referred to as free-market anarchism,[1] market anarchism,[2] private-property anarchism,[3] libertarian anarchism,[4]) is a libertarian political philosophy that advocates anarchy in the sense of the elimination of the state in favor of individual sovereignty in a free market.[5][6] In an anarcho-capitalist society, law enforcement, courts, and all other security services would be provided by privately funded competitors rather than through taxation, and money would be privately and competitively provided in an open market. Therefore, personal and economic activities under anarcho-capitalism would be regulated by privately run law rather than through politics."
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At least in terms of the role of the Federal government, the founding fathers of the 1700s were very similar to libertarians of today. That would be except for anarchno-clueless libertarians...