### Programme - Talk

Grounding in and after Bolzano

(Affiliated Workshop, English)

he aim of this workshop is to discuss Bolzano's theory of grounding (*Abfolge*) against the background of the recent debate on metaphysical grounding. Early on in the 19th century, Bernard Bolzano developed a very rich account of grounding that resembles modern approaches to metaphysical grounding in several respects. According to Bolzano, grounding is an objective ground-consequence relation among true propositions that can be adequately expressed by the connective 'because'. As is common in modern theories of grounding, Bolzano holds that grounding is irreflexive and asymmetric. Moreover, he systematically distinguishes between complete and partial grounds on the one hand and immediate and mediate grounds on the other. What is most remarkable is his attempt to characterize grounding in terms of entailment by means of certain structural constraints that concern the compositional complexity of grounds and consequences. This workshop brings together researchers with an interest in Bolzano and grounding in order to discuss Bolzano's ideas and shed light on Bolzano as a predecessor of the modern debate on metaphysical grounding. Given the close parallels between Bolzano's theory of grounding and modern accounts, a thorough understanding of Bolzano's ideas seems not only interesting in its own right but also promises to reveal important insights in the context of the current debate.

**Abstracts.**

**Edgar Morscher (Salzburg): The Axiomatization of Bolzano's Theory of ***Abfolge*: an Exercise in ''Rational Reconstruction''

Bolzano presented his informal theory of *Abfolge* in admirable clarity in his *Wissenschaftslehre*, §§ 198--222. A theory is hereby understood as a deductively closed set of sentences. In order to rationally reconstruct an informal theory, we have to make three substantial decisions: *first*, we have to fix the formal language within which we are going to reconstruct the theory in question; *second*, we must decide about the primitive term(s) which we take as the basis of the vocabulary in our reconstruction language; and *third*, we have to choose the primitive theses, i.e. axioms or postulates, on which we base the theory in its reconstructed form. As far as a rational reconstruction of Bolzano's theory of *Abfolge* is concerned, I propose to answer the three questions in the following way:
(1) As my language of reconstructions I take the language of modern quantification logic, augmented with a consistent segment of modern set theory (and not, as some would like to have it, the language of Bolzano's theory of collections or *Inbegriffe*).
(2) The primitive term on which I base the vocabulary of my language of reconstruction will be the 2-place predicate '*M* is the complete ground of *N*', where *M* and *N* are sets of (true) propositions (*Sätze an sich*) and *N* is a partial or the complete consequence of *M* (and not, as some would like to have it, the 2-place predicate '*M* is the complete ground of *P*' where *P* is a single true proposition).
(3) For my reconstruction I choose six postulates which determine the formal properties of the grounding relation (among them are not, as some would like to have it, special instances of the *Abfolge* relation such as 'For every proposition P: P is the complete ground of [P has truth]').
In my contribution I will explain why I make these decisions. In doing so, the focus of my interest turns from Bolzano's theory of *Abfolge* to the method of rational reconstruction for which Bolzano's theory serves as an illustrative example.

**Stefan Roski (Hamburg): Fundamental Truths and the PSR in Bolzano's Theory of Grounding (joint work with Benjamin Schnieder)**

Bernard Bolzano is often credited with developing the first rigorous theory of grounding in his main work *Theory of Science* (1837). One of the motivations to develop this theory was his concern with the Principle of Sufficient Reason (PSR) that, due to the influence of rationalism, was widely endorsed in his time. Against the background of his theory of grounding, Bolzano was in the position to point out that a number of arguments for this principle were wanting. In addition to that, he also developed original arguments to show that the PSR is false. In our talk we will investigate those arguments and show that one of them is of considerable systematic interest for the contemporary debate on grounding and fundamentality.

**Organisation**: Jan Claas (Hamburg) & Antje Rumberg (Constance). In cooperation with Benjamin Schnieder (Hamburg), with kind support of the SNF.

Chair: Jan Claas & Antje Rumberg

Time: 09:00-13:00, 13 September 2017 (Wednesday)

Location: SR 1.006

Arianna Betti

(University of Amsterdam, Netherlands)

Edgar Morscher

(University of Salzburg, Austria)

Stefan Roski

(University of Hamburg, Germany)