ABSTRACT
One of philosophy’s most influential thought experimenters is Ptolemy (87–150 ce), the inspiration of future mathematicians and geometers, as well as geographers and cosmologists. He sets out a homely view of the universe in the first book of the Almagest, and gives there various arguments that sit somewhere between ‘thought’ ones and real ones. In particular, Ptolemy argues that since all bodies fall to the centre of the universe, the Earth must be fixed there at the centre, otherwise falling objects would not be seen to drop towards the centre of the Earth.
