“Although I generally prefer negative theories – those which posit as few unempirical concepts* as possible – my own leanings in this particular case are toward Realism. My attraction to the theory is bolstered by one further consideration: I can see no way to account for the existence of certain items, e.g. pieces of music, plays, and novels, other than by conceiving of them as abstract entities. Here I am considerably inﬂuenced by the arguments of C.E.M. Joad (1891-1953).
Joad argued (, 267-70) that the play Hamlet, for example, could not reasonably be identiﬁed with any particular in the world: neither with an idea in Shakespeare’s mind, nor with any manuscript he wrote, nor with any printed edition of the text, nor with any particular production, nor with any audio or video recording of any particular production. For Hamlet could exist even if any one or several of these were not to exist. While Joad, himself, rightly expressed some difﬁdence about his own arguments, I think that they add considerable impetus to a theory which would posit abstract entities.
Although I am a Realist, I am a reluctant Realist. For, to be frank, there is something exceedingly peculiar about positing entities which exist (subsist) outside of space and time. I, personally, would prefer a theory which could dispense with such mysterious entities. But I ﬁnd the problems inherent in the various anti-Realist theories even more troubling. Realism is simply the better, in my estimation, of the available theories. But, like many other Realists, I do not much care for Realism. Recently one of my colleagues professed his repudiation of Realism by saying that he found the positing of abstract entities “ unintelligible ”. I share his displeasure. But I ﬁnd myself unable to adopt his own anti-Realist position because I cannot in turn believe that the anti-Realist theories provide any better answer or that they can be developed without themselves having to posit at least some abstract entities.”
Norman Swartz, Beyond Experience, pp. 270-272, available online for free.