Abstract

To salvage traditional logic and traditional square of opposition from the problem of existential import, logicians have been offering solutions for centuries. In this paper, firstly it will be argued that as far as we know, the historically first solution proposed by Abelard in 11th century and by Seuren in 2002 is actually a version of the O-Corner Interpretation of traditional logic, which is generally attributed to the 14th century logician Ockham. Secondly, it will be advocated that two systems of Abelard and of Ockham have the same logical power. Lastly, the main claim will be that Abelard’s and Seuren’s system shall be favored over Ockham’s system.