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Does Spanking Violate the Non-Aggression Principle?
Libertarianism centers around the nonaggression principle and a respect for property rights, which are derived from the axiom of self-ownership.
Libertarians condemn social institutions which violate the nonaggression principle and property rights. Taxation, national debts, fiat currency, unjust invasions, and the persecution and incarceration of nonviolent citizens through drug laws -- all these have been roundly and soundly criticized by libertarians through the decades.
The one thing that all these institutions have in common is that we, as individuals, can do next to nothing to oppose them. Even as a collective movement, not only has libertarianism been unable to shrink the unjust power of the State, but it's hard to see how the movement has even slowed the rate of its growth.
Libertarianism is fundamentally a moral philosophy with political implications -- however, libertarians have a habit of focusing on the political implications, which cannot be changed by any individual, and avoiding the personal implications of the moral philosophy, which can be put into practice by everyone.
For instance, while countless books have been written analyzing economics from a libertarian or Austrian perspective, very few have been written about how to apply Libertarian morality to parenting. Ayn Rand touched on parenting in a throwaway scene at Galt's Gulch in 'Atlas Shrugged,' and Murray Rothbard reaffirmed the right of adult children to leave abusive parents in 'Kids Lib,' but I do not know of any major work by a Libertarian or Objectivist focusing on parenting. Nathaniel Branden has touched on the subject in a few articles, but does not mention any particular discipline techniques.
Very few libertarians become bank robbers or Federal Reserve Chairmen (but I repeat myself). By far the most common aggression Libertarians will ever personally use or experience is the disciplining of children. This is a moral question central to our lives as parents, yet it has to my knowledge never been addressed in Libertarian literature.
So -- in terms of practical morality, the most essential question for libertarians to discuss is: does spanking violate the nonaggression principle?