 Whatever option one follows, in spelling out such theories one typically postulates a rich realm of properties. Traditionally, this is done by a so-called comprehension principle which, intuitively, asserts that, for any well-formed formula (“wff”) \(A\), with \(n\) free variables, \(x_1 , \ldots ,x_n\), there is a corresponding \(n\)-adic property. Following option 1, it goes as follows: