Sorites Agnosticism

The final departmental Colloquium of this year will be on Wednesday at the usual time (4.30pm) and place (A/009), and we are delighted to say that we have Professor Susanne Bobzien from All Souls College, Oxford, who will give a talk titled 'Sorites Agnosticism'.

Abstract:

‘When an object a is situated in the borderline area of a vague predicate F, then even for qualified individuals and with the context fixed there will be a viewpoint from which a looks like things that are F and another from which a looks like things that are not F.’ This observation forms the basis of the agnostic solution to theSorites paradox. In my talk I present the philosophical elements of this solution and briefly touch upon the logic that forms its backbone.  

The agnostic solution has as characteristic features: (1) It employs the distinction between contexts of evaluation and viewpoints of assessment. (2) It distinguishes two notions of borderlineness. (3) It defines the structure of vagueness using the quantified normal modal system QS4M+FINAX. (4) It interprets the modal operators factive-cognitively, so that if something is non-borderline F one can tell that it is F, whereas if it is borderline F one cannot tell whether it is F. (5) Consequently, if something is borderline, one cannot tell that it is borderline.

With (1) to (5) in place, the Sorites paradox can be solved using two straightforward assumptions: (i) that the universal conditional premise of the Sorites is untrue and (ii) that for any pair of adjacent objects in a Soritesseries with F one can’t rule out that if one is F so is the other, where ‘can’t rule out’ is structurally defined by the modal system QS4M+FINAX.

Some of the main strengths of the agnostic solution are that it can retain classical logic and bivalence without the shortcomings of epistemicism; that its formal apparatus is simple (quantified normal modal logic); and that it is immune to higher-order vagueness paradoxes.