||In Western philosophy the human capacity to conceive of or imagine various states of affairs has often been thought to be a good guide to whether the state of affairs is possible. For example, one might infer from the fact that they can conceive of a chair located at L in room R, that it is possible for the chair to be located at L in R. While it is natural to think that conceivability and imaginability provide some kind of evidence for believing that something is possible or impossible, it is often difficult to show why this should be the case. Often times we find something conceivable because we lack knowledge. For example, historically one might have found it possible for water to be something other than H2O because at the time the community did not know that water is H2O. If ignorance often explains conceivability and imaginability, how can we be certain at any given time that our conceptions are tracking the way the world is. Some of the main questions in the area of conceivability and imaginability are the following: does conceivability entail possibility or is it merely a good guide to possibility? Is conceivability more reliable or less reliable than inconceivability? What kind of possibility is conceivability linked to (physical, logical, metaphysical)?