"A Problem for Two-Dimensionalism? Comments to P. Mackie"

ORLANDO, ELEONORA

Instituto de Filosofía, Facultad de Filosofía y Letras, Buenos Aires

Workshop; Workshop on Modality and Identity; 2007

Grupo de Acción Filosófica (GAF)

  In her paper “How is necessary a posteriori  truth possible?”, Penelope Mackie focuses on the phenomenon of the necessary a posteriori, namely, the existence of truths that are both necessary –they hold in all possible worlds- and a posteriori  –they can only be known through experience. As is known, the combination of metaphysical necessity with epistemic aposterioricity or dependence on experience has been considered puzzling by many philosophers, including Kripke himself: how come that a sentence that is true in all possible worlds may depend on the experience of the actual world for its truth? As also known, Kripke has suggested an account of this puzzle generated by necessary a posteriori truth -the so-called “illusion of contingency”-, which has been in turn taken up by two-dimensionalist semanticists. In her paper, Mackie strongly criticizes two-dimensionalism, under the specific version of whatshe calls “a simple semantic two-dimensional account”. Mackie’s main thesis is that applying the genuine contingency explanation characteristic of the model of the simple semantic two-dimensional account trivializes the phenomenon of the necessary a posteriori: it makes it look as a rather uninteresting one, it does not do justice to the de re nature of modality –characterized by principles such as the Necessity of Identity (if two individuals are identical, they are necessarily identical), the Necessity of Origin (if a certain individual has a certain origin, it has it necessarily) and the Necessity of Humanity (if an individual is human, it is necessarily human), all of which are substantial de re essentialist principles.In my paper, I criticize Mackie´s position in three main respects:(i) it is not clear to me in what sense Penelope takes the necessary a posteriori to be a puzzling phenomenon; more specifically, why she seems to be thinking that its puzzling aspect is something other from the so-called ‘illusion of contingency’; (ii) assuming the proposed interpretation of two-dimensionalism, it is not clear to me why Penelope thinks that the two-dimensionalist account renders the notion of necessity involved in the necessary a posteriori  trivial;(iii) in my view, there are no clear reasons to interpret the association, characteristic of two-dimensionalist theories, of any statement containing a name with a statement containing a definite description in terms of the proposal of a semantic equivalence between the name and the rigidified version of the description at stake.