Caspar asks: can science tell us everything there is to know about the world? He tells us about a famous argument that it can’t, sometimes called ‘the knowledge argument’ or ‘the Mary argument’, due to philosopher Frank Jackson. If the argument is right, then there are certain aspects of the world that we can’t learn about through science. In particular, we can’t use science to learn what it is like to see red, or taste coffee, or have other experiences.