Saturday, August 12, 2006

Ockham on Goat-Stags and Chimaera

"(17) A nominal definition, on the other hand, is an expression that reveals explicitly what is conveyed by a word. For example, someone who wants to teach [someone] else what the name ‘white’ signifies says that it signifies the same as [does] the expression ‘something having a whiteness’. There can be this [kind of] definition not only for names of which ‘to be’ can be truly verified in reality, but also [for names] of [things] of which such predication is impossible. Thus ‘vacuum’, ‘non-being’, ‘impossible’, ‘infinite’, [and] ‘goat-stag’ have definitions. That is, there correspond to these names certain expressions that signify the same [things] that these words [do].

(18) It follows from this that, taking ‘definition’ in this sense, sometimes it is impossible to predicate the definition of the defined by means of the verb ‘is’, when both [the definition and the defined] are taken significatively. Thus, ‘A chimera is an animal composed of a goat and an ox’ (let that be its definition) is impossible. This [is so] because of an impossible implication, namely, [the one] by which it is implied [by this proposition] that something is composed of a goat and an ox. Nevertheless, the proposition “‘Chimera” and “animal composed of a goat and an ox” signify the same [things]’, in which the terms supposit materially, is true. By the first [proposition] speakers generally understand this second one, even though properly speaking it is another [proposition entirely]. Thus, just as, according to Priscian, one word is often put for another, as he illustrates in Constructions I, so [too] one expression is often put for another. Nevertheless, the conditional made up of such a defined and [its] definition is true. For ‘If something is a chimera, it is composed of a man and a lion’, and conversely, is true."

(Summa Logicae, Chapter 26)


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