ternary division, that is, a division of some domain into three mutually exclusive and jointly exhaustive possibilities, instead of the two of a simple binary division. The logic of such opposition is however not confined to the relationships exhibited by squares of opposition, which in fact leave quite a few things in the dark. It transpires that a square in only a square of opposition if a further condition is fulfilled apart from codifying a ternary division, and we shall look into what this is." /> Opposition, obversion, and duality - Simons Peter | sdvig press