Abstract

The main purpose of the article is to get clear what Leibniz's concerns about relations were. His: I do not believe that you will admit an accident that is in two subjects at the same time. My judgement about relations is that paternity in David is one thing, sonship in Solomon another, but that the relation common to both is a merely mental thing whose basis is the modifications of the individuals is best seen as akin to: Father is true of David. Son is true of Solomon. But Being a father of is not true of any individual. Leibniz, like modern nominalist Nelson Goodman, could not allow the ordered pair . To establish this I must argue against Hidé Ishiguro's claim that Leibniz should have straightforwardly constructed a logic of relations, and Jaakko Hintikka's claim that Leibniz could have allowed the use of relational predicates in such forms as (Ex) Rax and (Ey) Ryb. I must also argue that what they say about the windowlessness doctrine (especially the as if formulation) is beside the point.