Mathematical investigation, when done well, can confer understanding. This bare observation shouldn’t be controversial; where obstacles appear is rather in the effort to engage this observation with epistemology. The complexity of the issue of course precludes addressing it tout court in one paper, and I’ll just be laying some early foundations here. To this end I’ll narrow the field in two ways. First, I’ll address a specific account of explanation and understanding that applies naturally to mathematical reasoning: the view proposed (...) by Philip Kitcher and Michael Friedman of explanation or understanding as involving the unification of theories that had antecedently appeared heterogeneous. For the second narrowing, I’ll take up one specific feature (among many) of theories and their basic concepts that is sometimes taken to make the theories and concepts preferred: in some fields, for some problems, what is counted as understanding a problem may involve finding a way to represent the problem so that it (or some aspect of it) can be visualized. The final section develops a case study which exemplifies the way that this consideration – the potential for visualizability – can rationally inform decisions as to what the proper framework and axioms should be. The discussion of unification (in sections 3 and 4) leads to a mathematical analogue of Goodman’s problem of identifying a principled basis for distinguishing grue and green. Just as there is a philosophical issue about how we arrive at the predicates we should use when making empirical predictions, so too there is an issue about what properties best support many kinds of mathematical reasoning that are especially valuable to us. The issue becomes pressing via an examination of some physical and mathematical cases that make it seem unlikely that treatments of unification can be as straightforward as the philosophical literature has hoped. Though unification accounts have a grain of truth (since a phenomenon (or cluster of phenomena) called “unification” is in fact important in many cases) we are far from an analysis of what “unification” is.. (shrink)

There was a methodological revolution in the mathematics of the nineteenth century, and philosophers have, for the most part, failed to notice.2 My objective in this chapter is to convince you of this, and further to convince you of the following points. The philosophy of mathematics has been informed by an inaccurately narrow picture of the emergence of rigour and logical foundations in the nineteenth century. This blinkered vision encourages a picture of philosophical and logical foundations as essentially disengaged from (...) ongoing mathematical practice. Frege is a telling example: we have misunderstood much of what Frege was trying to do, and missed the intended significance of much of what he wrote, because our received stories underestimate the complexity of nineteenth-century mathematics and mislocate Frege’s work within that context. Given Frege’s perceived status as a paradigmatic analytic philosopher, this mislocation translates into an unduly narrow vision of the relation between mathematics and philosophy. This chapter surveys one part of a larger project that takes Frege as a benchmark to fix some of the broader interest and philosophical significance of nineteenth-century developments. To keep this contribution to a manageable.. (shrink)

A cluster of recent papers on Frege have urged variations on the theme that Frege’s conception of logic is in some crucial way incompatible with ‘metatheoretic’ investigation. From this observation, significant consequences for our interpretation of Frege’s understanding of his enterprise are taken to follow. This chapter aims to critically examine this view, and to isolate what I take to be the core of truth in it. However, I will also argue that once we have isolated the defensible kernel, the (...) sense in which Frege was committed to rejecting ‘metatheory’ is too narrow and uninteresting to support the con-. (shrink)

This paper uses the strengthened liar paradox as a springboard to illuminate two more general topics: i) the negation operator and the speech act of denial among speakers of English and ii) some ways the potential for acceptable language change is constrained by linguistic meaning. The general and special problems interact in reciprocally illuminating ways. The ultimate objective of the paper is, however, less to solve certain problems than to create others, by illustrating how the issues that form the topic (...) of this paper are more intricate than previously realised, and that they are related in delicate and somewhat surprising ways. (shrink)

This paper develops some respects in which the philosophy of mathematics can fruitfully be informed by mathematical practice, through examining Frege's Grundlagen in its historical setting. The first sections of the paper are devoted to elaborating some aspects of nineteenth century mathematics which informed Frege's early work. (These events are of considerable philosophical significance even apart from the connection with Frege.) In the middle sections, some minor themes of Grundlagen are developed: the relationship Frege envisions between arithmetic and geometry and (...) the way in which the study of reasoning is to illuminate this. In the final section, it is argued that the sorts of issues Frege attempted to address concerning the character of mathematical reasoning are still in need of a satisfying answer. (shrink)

It is widely believed that some puzzling and provocative remarks that Frege makes in his late writings indicate he rejected independence arguments in geometry, particularly arguments for the independence of the parallels axiom. I show that this is mistaken: Frege distinguished two approaches to independence arguments and his puzzling remarks apply only to one of them. Not only did Frege not reject independence arguments across the board, but also he had an interesting positive proposal about the logical structure of correct (...) independence arguments, deriving from the geometrical principle of duality and the associated idea of substitution invariance. The discussion also serves as a useful focal point for independently interesting details of Frege's mathematical environment. This feeds into a currently active scholarly debate because Frege's supposed attitude to independence arguments has been taken to support a widely accepted thesis (proposed by Ricketts among others) concerning Frege's attitude toward metatheory in general. I show that this thesis gains no support from Frege's puzzling remarks about independence arguments. (shrink)

The issues surrounding the Caesar problem are assumed to be inert as far as ongoing mathematics is concerned. This paper aims to correct this impression by spelling out the ways that, in their historical context, Frege's remarks would have had considerable resonance with work that other mathematicians such as Riemann and Dedekind were doing. The search for presentation‐independent characterizations of objects and global definitions was seen as bound up with fundamental methodological questions in complex analysis and number theory.

Setting out to understand Frege, the scholar confronts a roadblock at the outset: We just have little to go on. Much of the unpublished work and correspondence is lost, probably forever. Even the most basic task of imagining Frege's intellectual life is a challenge. The people he studied with and those he spent daily time with are little known to historians of philosophy and logic. To be sure, this makes it hard to answer broad questions like: 'Who influenced Frege?' But (...) the information vacuum also creates local problems of textual interpretation. Say we encounter a sentence that may be read as alluding to a scientific dispute. Should it be read that way? To answer, we'd need to address prior questions. Is it .. (shrink)

The issues surrounding the Caesar problem are assumed to be inert as far as ongoing mathematics is concerned. This paper aims to correct this impression by spelling out the ways that, in their historical context, Frege's remarks would have had considerable resonance with work that other mathematicians such as Riemann and Dedekind were doing. The search for presentation‐independent characterizations of objects and global definitions was seen as bound up with fundamental methodological questions in complex analysis and number theory.

Le choix de définitions « naturelles » ou « correctes » est un aspect fondamental de la recherche mathématique qui a été négligé dans l’étude de la connaissance mathématique. L’une des raisons qui expliquent cet abandon tient au sentiment qu’ont eu de nombreux auteurs que la préférence pour une définition au détriment d’une autre ne pouvait être que « simplement psychologique » ou « subjective » en sorte que de tels jugements ne pouvaient pas être philosophiquement intéressants. Je discute ici (...) d’un sens minimal du terme « objectif » selon lequel on pourrait de manière défendable argumenter que de tels choix de définitions préférées sont objectivement corrects, en dépit des raisons apparemment « esthétiques » qui soutiennent un tel jugement.Choosing « natural » or « correct » definitions is a fundamental aspect of mathematical research that has been neglected in studies of mathematical knowledge. One reason for this neglect may be a sense that many writers seem to have that a preference for one definition over another can only be « merely psychological » and « subjective » in a way that prevents such judgments from being philosophically interesting. I discuss a minimal sense of « objective » according to which such choices of preferred definitions can be defensibly argued to be objectively correct, despite the seemingly « aesthetic » grounds for the judgement. (shrink)

I’ll use an extension of the “smidget” example Soames sets out on pages 165-172 to bring out the point. Groups A and B are disjoint and satisfy certain regularity conditions. Recall that the extension and anti-extension are specified by a pair of sufficient conditions. We specify: every member of group A is a smidget and every member of group B is not a smidget. No decision is made about persons that are outside groups A and B. It is, of course, (...) crucial that the smidgethood of the indeterminate cases is genuinely left open. What is the cash value of the difference between leaving a case unsettled and settling a case as indeterminate? Here is one difference: when a case is left unsettled, speakers of the language can resolve it later, if there is some reason to do so. This provides a simple model of key features of legal stipulations, at least in circumstances like U.S. constitutional law, where a single body can introduce an expression and stipulate how it is to be interpreted. (shrink)

Mathematical investigation, when done well, can confer understanding. This bare observation shouldn’t be controversial; where obstacles appear is rather in the effort to engage this observation with epistemology. The complexity of the issue of course precludes addressing it tout court in one paper, and I’ll just be laying some early foundations here. To this end I’ll narrow the field in two ways. First, I’ll address a specific account of explanation and understanding that applies naturally to mathematical reasoning: the view proposed (...) by Philip Kitcher and Michael Friedman of explanation or understanding as involving the unification of theories that had antecedently appeared heterogeneous. For the second narrowing, I’ll take up one specific feature (among many) of theories and their basic concepts that is sometimes taken to make the theories and concepts preferred: in some fields, for some problems, what is counted as understanding a problem may involve finding a way to represent the problem so that it (or some aspect of it) can be visualized. The final section develops a case study which exemplifies the way that this consideration – the potential for visualizability – can rationally inform decisions as to what the proper framework and axioms should be. The discussion of unification (in sections 3 and 4) leads to a mathematical analogue of Goodman’s problem of identifying a principled basis for distinguishing grue and green. Just as there is a philosophical issue about how we arrive at the predicates we should use when making empirical predictions, so too there is an issue about what properties best support many kinds of mathematical reasoning that are especially valuable to us. The issue becomes pressing via an examination of some physical and mathematical cases that make it seem unlikely that treatments of unification can be as straightforward as the philosophical literature has hoped. Though unification accounts have a grain of truth (since a phenomenon (or cluster of phenomena) called “unification” is in fact important in many cases) we are far from an analysis of what “unification” is.. (shrink)

A cluster of recent papers on Frege have urged variations on the themethat Frege’s conception of logic is in some crucial way incompatible with‘metatheoretic’ investigation. From this observation, significant consequencesfor our interpretation of Frege’s understanding of his enterprise are taken tofollow. This chapter aims to critically examine this view, and to isolate whatI take to be the core of truth in it. However, I will also argue that once wehave isolated the defensible kernel, the sense in which Frege was committedto (...) rejecting ‘metatheory’ is too narrow and uninteresting to support the con-clusions drawn from the thesis by its proponents. (shrink)

I’ll use an extension of the “smidget” example Soames sets out on pages 165-172 to bring out the point. Groups A and B are disjoint and satisfy certain regularity conditions. Recall that the extension and anti-extension are specified by a pair of sufficient conditions. We specify: every member of group A is a smidget and every member of group B is not a smidget. No decision is made about persons that are outside groups A and B. It is, of course, (...) crucial that the smidgethood of the indeterminate cases is genuinely left open. What is the cash value of the difference between leaving a case unsettled and settling a case as indeterminate? Here is one difference: when a case is left unsettled, speakers of the language can resolve it later, if there is some reason to do so. This provides a simple model of key features of legal stipulations, at least in circumstances like U.S. constitutional law, where a single body can introduce an expression and stipulate how it is to be interpreted. (shrink)

I’ll use an extension of the “smidget” example Soames sets out on pages 165-172 to bring out the point. Groups A and B are disjoint and satisfy certain regularity conditions. Recall that the extension and anti-extension are specified by a pair of sufficient conditions. We specify: every member of group A is a smidget and every member of group B is not a smidget. No decision is made about persons that are outside groups A and B. It is, of course, (...) crucial that the smidgethood of the indeterminate cases is genuinely left open. What is the cash value of the difference between leaving a case unsettled and settling a case as indeterminate? Here is one difference: when a case is left unsettled, speakers of the language can resolve it later, if there is some reason to do so. This provides a simple model of key features of legal stipulations, at least in circumstances like U.S. constitutional law, where a single body can introduce an expression and stipulate how it is to be interpreted. (shrink)

A selection of essays dedicated to Hans Herzberger with affection and gratitude for both his profound work and his lasting example. Contributors: I. Levi (on whether and how a rational agent should be seen as a maximizer of some cognitive value), C. Normore (on medieval accounts of logical validity), J. P. Tappenden (on the local influences on Frege's doctrines), A. Urquhart (on the inexpressible), A. C. Varzi (on dimensionality and the sense of possibility), and S. Yablo (on content and carvings, (...) and from there to mathematical realism). (shrink)