War and Paradise, An Interview with Marcus Rossberg

Marcus Rossberg has been in St Andrews since 2001, finished his PhD in March 2006, and is now a postdoctoral research fellow here. His interests lie in philosophy of mathematics, philosophical logic and metaphysics. Thanks to this, he had some illuminating advice on career prospects, as well as sharing his insight on the differences between continental and analytical philosophy and other battlefronts

War and Paradise, An Interview with Marcus Rossberg

Marcus Rossberg has been in St Andrews since 2001, finished his PhD in March 2006, and is now a postdoctoral research fellow here. His interests lie in philosophy of mathematics, philosophical logic and metaphysics. Thanks to this, he had some illuminating advice on career prospects, as well as sharing his insight on the differences between continental and analytical philosophy and other battlefront

The Convenience of the Typesetter; Notation and Typography in Frege’s Grundgesetze der Arithmetik

We discuss the typography of the notation used by Gottlob Frege in his Grundgesetze der Arithmetik

Cantor on Frege's Foundations of Arithmetic: Cantor's 1885 Review of Frege's Die Grundlagen der Arithmetik

In 1885, Georg Cantor published his review of Gottlob Frege's Grundlagen der Arithmetik. In this essay, we provide its first English translation together with an introductory note. We also provide a translation of a note by Ernst Zermelo on Cantor's review, and a new translation of Frege's brief response to Cantor. In recent years, it has become philosophical folklore that Cantor's 1885 review of Frege's Grundlagen already contained a warning to Frege. This warning is said to concern the defectiveness of Frege's notion of extension. The exact scope of such speculations varies and sometimes extends as far as crediting Cantor with an early hunch of the paradoxical nature of Frege's notion of extension. William Tait goes even further and deems Frege 'reckless' for having missed Cantor's explicit warning regarding the notion of extension. As such, Cantor's purported inkling would have predated the discovery of the Russell-Zermelo paradox by almost two decades. In our introductory essay, we discuss this alleged implicit (or even explicit) warning, separating two issues: first, whether the most natural reading of Cantor's criticism provides an indication that the notion of extension is defective; second, whether there are other ways of understanding Cantor that support such an interpretation and can serve as a precisification of Cantor's presumed warning

Logical consequence for nominalists

It is often claimed that nominalistic programmes to reconstruct mathematics fail, since they will at some point involve the notion of logical consequence which is unavailable to the nominalist. In this paper we use an idea of Goodman and Quine to develop a nominalistically acceptable explication of logical consequence

Introduction to Abstractionism

First paragraph: Abstractionism in philosophy of mathematics has its origins in Gottlob Frege’s logicism—a position Frege developed in the late nineteenth and early twentieth century. Frege’s main aim was to reduce arithmetic and analysis to logic in order to provide a secure foundation for mathematical knowledge. As is well known, Frege’s development of logicism failed. The infamous Basic Law V— one of the six basic laws of logic Frege proposed in his magnum opus Grundgesetze der Arithmetik—is subject to Russell’s Paradox. The striking feature of Frege’s Basic Law V is that it takes the form of an abstraction principle

Demythologizing the Third Realm: Frege on Grasping Thoughts

In this paper, I address some puzzles about Frege’s conception of how we “grasp ” thoughts. I focus on an enigmatic passage that appears near the end of Frege’s great essay “The Thought. ” In this passage Frege refers to a “non-sensible something ” without which “everyone would remain shut up in his inner world. ” I consider and criticize Wolfgang Malzkorn’s interpretation of the passage. According to Malzkorn, Frege’s view is that ideas [Vorstellungen] are the means by which we grasp thoughts. My counter-proposal is that language enables us to grasp thoughts (ideas are merely their baggage or “trappings, ” as Frege puts it). One significant consequence of my interpretation is that it helps challenge the standard reading of Frege according to which he is a metaphysical platonist about thoughts. My interpretation thus provides support for the deflationary, anti-ontological reading spelled out by read-ers like Thomas Ricketts and Wolfgang Carl. As Ricketts puts it, Frege’s distinction between the objective and the subjective, rather than being an ontological doctrine, “lodges in the contrast be-tween asserting something and giving vent to a feeling.

A Grassmann integral equation

The present study introduces and investigates a new type of equation which is called Grassmann integral equation in analogy to integral equations studied in real analysis. A Grassmann integral equation is an equation which involves Grassmann integrations and which is to be obeyed by an unknown function over a (finite-dimensional) Grassmann algebra G_m. A particular type of Grassmann integral equations is explicitly studied for certain low-dimensional Grassmann algebras. The choice of the equation under investigation is motivated by the effective action formalism of (lattice) quantum field theory. In a very general setting, for the Grassmann algebras G_2n, n = 2,3,4, the finite-dimensional analogues of the generating functionals of the Green functions are worked out explicitly by solving a coupled system of nonlinear matrix equations. Finally, by imposing the condition G[{\bar\Psi},{\Psi}] = G_0[{\lambda\bar\Psi}, {\lambda\Psi}] + const., 0<\lambda\in R (\bar\Psi_k, \Psi_k, k=1,...,n, are the generators of the Grassmann algebra G_2n), between the finite-dimensional analogues G_0 and G of the (``classical'') action and effective action functionals, respectively, a special Grassmann integral equation is being established and solved which also is equivalent to a coupled system of nonlinear matrix equations. If \lambda \not= 1, solutions to this Grassmann integral equation exist for n=2 (and consequently, also for any even value of n, specifically, for n=4) but not for n=3. If \lambda=1, the considered Grassmann integral equation has always a solution which corresponds to a Gaussian integral, but remarkably in the case n=4 a further solution is found which corresponds to a non-Gaussian integral. The investigation sheds light on the structures to be met for Grassmann algebras G_2n with arbitrarily chosen n.Comment: 58 pages LaTeX (v2: mainly, minor updates and corrections to the reference section; v3: references [4], [17]-[21], [39], [46], [49]-[54], [61], [64], [139] added