Hypothetico-deduction—A method of reasoning widely used in the Western world for a very long time. An example from history is found in De Stella Martis by Kepler, who was puzzled by the problem of the shape of the orbit of Mars. Unable to figure it out by empirical observation, Kepler decided to simply suppose that the orbit was elliptical. Following this hypothesis, he worked out positions for the planet that corresponded well with its observed positions. Thus his hypothesis was not formed on the basis of previous observations, as it would have been had Kepler followed the empirical method. Rather, it was devised by speculation. The observations were then deductively brought into line with that speculation. See Abduction, Deduction, Induction.