CEFISES Seminar: Peter Verdée, « On indirect verification »

Note the time change: we will start at 14h30 instead of the usual 14h00.

Livestream https://youtube.com/live/NBf4DgacoA8

Series: Work-in-Progress

Speaker: Peter Verdée (UCLouvain)

Title: « On indirect verification »

Abstract:

In this explorative talk, I will discuss a remarkable non-Boolean phenomenon that very diverse aspects of human belief systems have in common: the fact that the truth of or the belief in certain disjunctive properties P-or-Q is not reducible to the truth of or the belief in either of the disjuncts P and Q. We will discuss three important cases from very different parts of our belief systems. The first is the case of measurable properties in quantum mechanics (in the sense of the property of a system being in an eigenstate of a Hermitian operator with a specific eigenvalue – e.g., an isolated electron being positioned in a specific region of 3d space). The second case is the supervaluationist interpretation of vagueness where a disjunction can be supertrue without either of the disjuncts being supertrue. The final case concerns what S. Yablo calls reductive truthmakers, i.e., the most parsimonious parts of the domain of discourse that manage to make a sentence true.  I will explore whether there is a common formal structure for all these phenomena and will suggest that the double-orthogonal-complement (DOC) closure of sets of verifiers may provide such a structure. In such a structure, one can distinguish between direct verifiers (those that correspond to the disjuncts) and indirect verifiers (those that belong to the DOC closure of the union of the verifiers of the disjuncts). We will explore the philosophical meaning of this distinction.