Abstract

Traditionally, philosophers have used the analytic/synthetic, a priori/a posteriori, and necessary/contingent distinctions to categorize statements. And traditionally, philosophers have used these distinctions to categorize necessary statements as a priori statements. Yet certain statements seem better categorized as necessary and a posteriori. Examples of such statements include: Heat is the form of energy constituted by the motion of atoms and molecules in solids; Gold is the element with atomic number 79; and Water is H$\sb2$O. For while we believe that these statements express empirical discoveries, we also believe that they express the essence of their subjects. ;I wish to justify the claim that these statements are both necessary and a posteriori. My justification includes a synthesis of the causal theory of reference with the network theory of meaning. But once this synthesis is carried out, we have a rather complicated notion of necessity. We no longer have one notion of necessity, but four notions. One notion is the logical positivist's. A statement is necessary if it expresses a linguistic convention. The second notion is the network theorist's. A statement is necessary if it is central to our theoretical network. The third notion is the causal theorist's. A statement is necessary if it is a singular statement of identity between two rigid designators. And the fourth notion is the essentialist's. A statement is necessary if the predicate expresses the essence of the subject. But this essence must be a structural property that plays an explanatory role within our theoretical network. Of these four notions of necessity, only the first must be a priori. The other three are ultimately a posteriori. Statements - fall under the fourth notion. And thus, they are necessary and a posteriori.