Forms More Real Than the Things That Copy Them

Plato's theory of Forms places the fullest reality not in the changeable particular things encountered by the senses, a particular triangle drawn in sand, a particular beautiful face, but in the eternal, unchanging Forms those particulars merely participate in and imperfectly resemble, the Form of Triangularity itself, the Form of Beauty itself, existing in a realm accessible not to the senses but to reason alone; a particular red rose is red, on this account, because it participates in the Form of Redness, and the rose's redness is derivative and imperfect compared to the Form's own perfect, unchanging redness. Aristotle accepted his teacher's basic realist commitment, that universals are genuinely real and not mere names, while sharply rejecting the separate realm, arguing instead that universals exist only immanently, in the particular things that instantiate them, so that redness exists fully and only in actual red things, with no further Form of Redness floating free in some separate intelligible world; this more moderate realism became the more influential position within medieval Aristotelian scholasticism specifically because it avoided Plato's difficulty of explaining how a particular thing here, in the changing physical world, could ever really participate in or be connected to a Form existing in an entirely separate realm.