In an attempt to get us to take seriously the idea that reality might be very different from how it seems, Descartes introduced an all-powerful demon. This demon, we are to suppose, is causing us to hallucinate, to have experiences that do not correspond to anything real. The experiences in question are the perceptual experiences that we are having at the moment and those we remember having in the past: the experiences that we unthinkingly take to be revealing the world to us. The point of this scenario is to lead us to appreciate that our experience does not guarantee that the world is as we normally believe it to be. Let us vary the scenario. The allpowerful demon informs us that it has not been providing us with hallucinatory experiences – the world really is pretty much as it seems – but it has instead taken the decision to abolish time.