The questions posed by such an approach would be worthy of attention on another day as would, indeed, the questions raised by Nozick's own position. For today, however, what interested me in the piece in question was the way it posed a problem for standard kinds of libertarian argument which go from uses of "free market" in a general, philosophical sense, to descriptive claims about existing market structures taken, unproblematically to exemplify and actualize the philosophical view. The author of the piece is right to describe the tendency to make this move as a form of "conflation" and the conflation it involves is a general one of identifying positions of political philosophy with actual institutional arrangements around us in the societies in which we live.
What this points to is the need to distinguish clearly between the ideals political philosophy sets out and the often imperfect ways in which these are represented in political situations. Kant, for one, was always keen to emphasise this point which is why he speaks of forms of government as imperfect representations of ideas. Keeping this point in mind is also what allows political philosophy to retain a critical edge, something badly needed, particularly in the light of the glaring injustices that decidedly plague social arrangements.