For a moment leave aside whether you believe or disbelieve in the existence of ghosts. Would you know one if you saw it?
Once, I would have said yes. I would have had a picture in mind of a spectral figure — the familiar trope of popular media — or perhaps an orb, a shadowy shape, or some kind of purposeful, unseen force. However, there is a much deeper history to the ghost (a secret history, in fact, as Claude Lecouteux’s work points out), and one that ties it to our concepts of life, death, and our relationships with the social order and the natural world around us. And these days, although some of the details of my conceptions may remain the same, the simple associations I had given to ghostly phenomena have been erased from my mind by a brief conversation and some deep reading.