Quoted from Bryan Caplan's Appendix to his anarchist FAQ:
A number of critics have rejected my proferred definition of anarchism, which may be found in The American Heritage College Dictionary:... The theory or doctrine that all forms of government are unnecessary, oppressive, and undesirable and should be abolished.
The underlying complaint appears to be that anarcho-capitalists are not really anarchists, and that I have thus selected an overly inclusive definition. There are two frequently repeated arguments against my definition, which I respectively dub The Philological Argument and the Historical Argument.
The Philological Argument. Several critics have noted the origin of the term "anarchy," which derives from the Greek "arkhos," meaning "ruler," and the prefix "an-," meaning "without." It is therefore suggested that in my definition the word "government" should be replaced with the word "domination" or "rulership"; thus re-written, it would then read: "The theory or doctrine that all forms of rulership are unnecessary, oppressive, and undesirable and should be abolished."
The Historical Argument. A second popular argument states that historically, the term "anarchism" has been clearly linked with anarcho-socialists, anarcho-communists, anarcho-syndicalists, and other enemies of the capitalist system. Hence, the term "anarcho-capitalism" is a strange oxymoron which only demonstrates ignorance of the anarchist tradition.
The major premise of the Philological Argument errs in assuming that the current meaning of words can be discovered by investigating their historical origins. This is plainly in error. The word "book" means whatever people happen to have in mind when they think of "books"; if historical investigation were to discover that the term derives from ancient Egyptian, and at that time meant "parchment," this would not show that current usage is "wrong." It would show that words change their meaning. Thus, my suggested definition is preferable to the definition based upon the Greek origin of the word "anarchy," because my definition fits more closely with the standard usage of most English speakers in general, and the standard usage of Internet users in particular.
The major premise of the Historical Argument is similarly flawed. Before the Protestant Reformation, the word "Christian," had referred almost entirely to Catholics (as well as adherents of the Orthodox Church) for about one thousand years. Does this reveal any linguistic confusion on the part of Lutherans, Calvinists, and so on, when they called themselves "Christians"? Of course not. It merely reveals that a word's historical usage does not determine its meaning. It is yet another example of the distinction between meaning and reference (which is perhaps best illustrated by the over-used example "Oedious wanted to marry Jocasta. Jocasta is Oedipus' mother. But Oedipus did not want to marry his mother." See e.g. John Searle's Intentionality.).
Of course, people with a different definition are not "wrong"; as any examination of a dictionary will reveal, the same sound can have an arbitrarily large number of distinct meanings. All that matters is that the particular meaning one has in mind is clear. Once this is accomplished, any definition, however idiocyncratic, is acceptable. The only danger to guard against is equivocation; that is, to use the idiocyncratic definition half the time, the normal one the rest of the time, and reach valid conclusions about absolutely nothing.
While the two most popular arguments for the definitional impossibility of anarcho-capitalism are erroneous, this does not preclude the creation of other exclusive definitions. (E.g., "Anarchism is what I advocate. Anything that I disagree with is, by definition, not 'anarchism.'") Rather than object to any other proposed definition, I simply make this blanket reply: Let us designate anarchism(1) anarchism as you define it. Let us desiginate anarchism(2) anarchism as I and the American Heritage College Dictionary define it. This is a FAQ about anarchism(2).