I remember reading a whole essay by Jacques Derrida about this exact question, and how it remains open: http://www.occt.ox.ac.uk/sites/default/files/derrida_pl

I remember reading a whole essay by Jacques Derrida about this exact question, and how it remains open: http://www.occt.ox.ac.uk/sites/default/files/derrida_platos_pharmacy.pdf http://www.occt.ox.ac.uk/sites/default/files/derrida_platos_... Plato is a great favorite of these French post-structuralist thinkers for exactly how he always leaves room for more questions, never giving you a final answer.