Abstract

‘Is being one only one? – The Argument for the Uniqueness of Platonic Forms’ Abstract: Each Form is unique in number; no two numerically distinct Forms can share the same nature. Plato argues for this claim in Republic X. I identify the metaphysical principles Plato presupposes in the premises of the argument, by examining the reasoning behind them, and offer a reconstruction of the argument showing the principles in use. I argue that the metaphysical significance of the argument’s conclusion is to establish that if a Form F were not unique, if there were many Forms F, their nature would alter along with their number: a Form cannot recur without change in its constitution. This is why there can be only one Form for each character in the world.