Ragna Talea Oeynhausen
LMU Munich
The aim of this paper is to evaluate whether Carnap’s pluralism falls victim to the collapse argument against logical pluralism. I first want to illustrate two correspondences between logical pluralism and Carnap’s pluralism that raise hope that the collapse argument is tansferable to the latter. For now, I will restrict myself to the upward collapse argument for ascending chains of entailing logics.
First, we need a chain of ascending linguistic frameworks, in particular, a basis that they all agree on. This is provided by the existential quantifier which will be interpreted as a formal univocal expression. While all linguistic frameworks share the same existential quantifier, they may—following Thomasson (2015)—differ in what entities they ascribe existence to. This way, we get an ascending chain of linguistics frameworks (where some entities might be accepted in higher but not in lower frameworks).
Secondly, lower linguistic frameworks ought not contradict the existence of entities that are accepted in higher ones. If an entity of a higher framework belongs to all lower frameworks, then the entity’s existence is accepted throughout all languages (by construction). The interesting case is when an entity does not belong to lower frameworks but is accepted in higher ones. Lower frameworks cannot contradict the existence of the entity in question as they lack the expressive power to talk about this entity. Indeed, Carnap claims that whenever we raise the general existence question “Are there X?” we do not seriously consider a negative reply to this question. Thus, we should either grant the existence of the entity in question or withhold judgment.
After having modified the two premises of the collapse argument as above we can directly apply the collapse argument to Carnap’s pluralism. In a last step, I will discuss the implications of this result.
Chair: Marvin Thinschmidt
Time: September 13th, 11:20 – 11:50
Location: SR 1.005
SOPhiA 2026 