Kierkegaard on existence

". . . whether I am moving in the world of sensate palpability or in the world of thought, I never reason in conclusion to existence, but I reason in conclusion from existence. For example, I do not demonstrate that a stone exists but that something which exists is a stone. The court of law does not demonstrate that a criminal exists but that the accused, who does indeed exists, is a criminal. Whether one wants to call existence an accessorium [addition] or the eternal prius [presupposition], it can never be demonstrated."

--Soren Kierkegaard, from Philosophical Fragments