text: in politics why communists are called leftist (left) ?   to answer your question properly:  in france after the french revolution the more politically radical groups in the estates general (as the parliament was called) sat to the left of the presidential chair. the pracise became common in other legislatures and the terms 'left' and 'right' became an easy way of defining relative politcal alignment.  n.b. it didn't begin in the us congress