This paper explores the set theoretic assumptions used in the current published proof of Fermat's Last Theorem, how these assumptions figure in the methods Wiles uses, and the currently known prospects for a proof using weaker assumptions.

Parsimony is a virtue of empirical theories. Is it also a virtue of philosophical theories? I review four contemporary accounts of the virtue of parsimony in empirical theorizing, and consider how each might apply to two prominent appeals to parsimony in the philosophical literature, those made on behalf of physicalism and on behalf of nominalism. None of the accounts of the virtue of parsimony extends naturally to either of these philosophical cases. This suggests that in typical philosophical contexts, ontological simplicity (...) has no evidential value. (shrink)

ABSTRACT Our aim in this article is to offer a new justification for preferring theories that are more quantitatively parsimonious than their rivals. We discuss cases where it seems clear that those involved opted for more quantitatively parsimonious theories. We extend previous work on quantitative parsimony by offering an independent probabilistic justification for preferring the more quantitatively parsimonious theories in particular episodes of theory choice. Our strategy allows us to avoid worries that other considerations, such as pragmatic factors of computational (...) tractability and so on, could be the driving ones in the historical cases under consideration. _1_ Introduction _2_ Three Desiderata _2.1_ Limiting _2.2_ Robustness _2.3_ Breadth _2.3.1_ A limited success for Baker _2.3.2_ Rejecting Baker’s analysis _2.4_ The proposal _3_ Probabilistically Additive Hypotheses and a Bayesian Account: The Limpid Rationale Relativized and Reconsidered _3.1_ Neutrinos and beta decay _3.2_ Avogadro’s hypothesis _3.3_ Postulation of Neptune _4_ Conclusion. (shrink)

This paper elaborates on relationalism about space and time as motivated by a minimalist ontology of the physical world: there are only matter points that are individuated by the distance relations among them, with these relations changing. We assess two strategies to combine this ontology with physics, using classical mechanics as example: the Humean strategy adopts the standard, non-relationalist physical theories as they stand and interprets their formal apparatus as the means of bookkeeping of the change of the distance relations (...) instead of committing us to additional elements of the ontology. The alternative theory strategy seeks to combine the relationalist ontology with a relationalist physical theory that reproduces the predictions of the standard theory in the domain where these are empirically tested. We show that, as things stand, this strategy cannot be accomplished without compromising a minimalist relationalist ontology. (shrink)

The desire to minimize the number of individual new entities postulated is often referred to as quantitative parsimony. Its influence on the default hypotheses formulated by scientists seems undeniable. I argue that there is a wide class of cases for which the preference for quantitatively parsimonious hypotheses is demonstrably rational. The justification, in a nutshell, is that such hypotheses have greater explanatory power than less parsimonious alternatives. My analysis is restricted to a class of cases I shall refer to as (...) additive. Such cases involve the postulation of a collection of qualitatively identical individual objects which collectively explain some particular observed phenomenon. Especially clear examples of this sort occur in particle physics. 1 Introduction 2 Particle physics: a case study 3 Three kinds of simplicity 4 Explanatory power 5 Explanation and non-observation 6 Parsimony and scientific methodology 7 Conclusions. (shrink)

Thomas Holden presents a fascinating study of theories of matter in the seventeenth and eighteenth centuries. These theories were plagued by a complex of interrelated problems concerning matter's divisibility, composition, and internal architecture. Is any material body infinitely divisible? Must we posit atoms or elemental minima from which bodies are ultimately composed? Are the parts of material bodies themselves material concreta? Or are they merely potentialities or possible existents? Questions such as these -- and the press of subtler questions hidden (...) in their amibiguities -- deeply unsettled philosophers of the early modern period. They seemed to expose serious paradoxes in the new world view pioneered by Galileo, Descartes, and Newton. The new science's account of a fundamentally geometrical Creation, mathematicizable and intelligible to the human inquirer, seemed to be under threat. This was a great scandal, and the philosophers of the period accordingly made various attempts to disarm the paradoxes. All the great figures address the issue: most famously Leibniz and Kant, but also Galileo, Hobbes, Newton, Hume, and Reid, in addition to a crowd of lesser figures. Thomas Holden offers a brilliant synthesis of these discussions and presents his own overarching interpretation of the controversy, locating the underlying problem in the tension between the early moderns' account of material parts on the one hand and the program of the geometrization of nature on the other. (shrink)

The question of what truths are necessary in the broadest possible sense is a difficult one to answer, as is the question of what the limits are to what is possible. (Most people would see these two questions as different sides of the same coin, of course, since many think the question of what is possible is just the question of what is not necessarily ruled out). We have three general sorts of strategies for determining whether something is necessary (or (...) possible). We can identify it in a class that we were previously sure was a class of things that are necessary – we might show it is a theorem of a logical system that we have confidence in, or that the sentence appears to be true simply in virtue of the meanings of the words, or that it is a true statement involving names or about natural kinds of the “necessary a posteriori” sort discussed by Kripke and Putnam, and there are perhaps other classes of claims which we are prepared to accept are necessary if true.1 Likewise, we might establish the possibility of something occurring by reference to a class of well-established or uncontroversial possibilities: e.g. we are inclined to think that it is possible (in the broadest sense) for an event to occur in the future if one of the same kind has occurred in the past. (shrink)

In this paper I present the Discrete Space-Time Thesis, in a way which enables me to defend it against various well-known objections, and which extends to the discrete versions of Special and General Relativity with only minor difficulties. The point of this presentation is not to convince readers that space-time really is discrete but rather to convince them that we do not yet know whether or not it is. Having argued that it is an open question whether or not space-time (...) is discrete, I then turn to some possible empirical evidence, which we do not yet have. This evidence is based on some slight differences between commonly occurring differential equations and their discrete analogs. (shrink)

Let us say that an extended object is “composed wholly of simples” just in case it is an aggregate of absolutely unextended parts spread throughout an extended region—that is, just in case there is a set S such that: every member is a point-sized part of the object, and for every x, x is part of the object if and only if it has a part in common with some member of S. Could a truly extended substance be composed entirely (...) of unextended parts? Reflection upon the fact that it must be at least possible for extended objects to touch one another suggests that the answer to this question is: No. (shrink)

In this paper, I motivate the view that quantitative parsimony is a theoretical virtue: that is, we should be concerned not only to minimize the number of kinds of entities postulated by our theories (i. e. maximize qualitative parsimony), but we should also minimize the number of entities postulated which fall under those kinds. In order to motivate this view, I consider two cases from the history of science: the postulation of the neutrino and the proposal of Avogadro's hypothesis. I (...) also consider two issues concerning how a principle of quantitative parsimony should be framed. (shrink)

Let us say that a thing is gunky just in case every part of that thing has proper parts. The idea that all physical objects are gunky seems sufficiently sweeping, interesting, and plausible that it is worth examining. However, there is a difficulty. The features of an extended object can surely vary continuously. If an object is gunky then it cannot have point-sized parts which have no further parts. But how can one conceive of a continuous variation in features other (...) than as the obtaining of different features at different point sized locations? (shrink)

In Infinity and the Mind, Rudy Rucker leads an excursion to that stretch of the universe he calls the "Mindscape," where he explores infinity in all its forms: potential and actual, mathematical and physical, theological and mundane. Here Rucker acquaints us with Gödel's rotating universe, in which it is theoretically possible to travel into the past, and explains an interpretation of quantum mechanics in which billions of parallel worlds are produced every microsecond. It is in the realm of infinity, he (...) maintains, that mathematics, science, and logic merge with the fantastic. By closely examining the paradoxes that arise from this merging, we can learn a great deal about the human mind, its powers, and its limitations. Using cartoons, puzzles, and quotations to enliven his text, Rucker guides us through such topics as the paradoxes of set theory, the possibilities of physical infinities, and the results of Gödel's incompleteness theorems. His personal encounters with Gödel the mathematician and philosopher provide a rare glimpse at genius and reveal what very few mathematicians have dared to admit: the transcendent implications of Platonic realism. (shrink)

A version of relationism that takes spatiotemporal structures—spatial geometry and a standard of inertia—to supervene on the history of relations between bodies is described and defended. The account is used to explain how the relationist should construe models of Newtonian mechanics in which absolute acceleration manifestly does not supervene on the relations; Ptolemaic and Copernican models for example. The account introduces a new way in which a Lewis-style ‘best system’ might capture regularities in a broadly Humean world; a defence is (...) given against a charge of indeterminism that applies to any such approach to laws. (shrink)

The desire to minimize the number of individual new entities postulated is often referred to as quantitative parsimony. Its influence on the default hypotheses formulated by scientists seems undeniable. I argue that there is a wide class of cases for which the preference for quantitatively parsimonious hypotheses is demonstrably rational. The justification, in a nutshell, is that such hypotheses have greater explanatory power than less parsimonious alternatives. My analysis is restricted to a class of cases I shall refer to as (...) additive. Such cases involve the postulation of a collection of qualitatively identical individual objects which collectively explain some particular observed phenomenon. Especially clear examples of this sort occur in particle physics.1Introduction2Particle physics: a case study3Three kinds of simplicity4Explanatory power5Explanation and non‐observation6Parsimony and scientific methodology7Conclusions. (shrink)

The surviving sources on the Stoic theory of division reveal that the Stoics, particularly Chrysippus, believed that bodies, places and times were such that all of their parts themselves had proper parts. That is, bodies, places and times were composed of gunk. This realisation helps solve some long-standing puzzles about the Stoic theory of mixture and the Stoic attitude to the present.

I argue for the possibility of hypergunk: that is, it is possible that there exists an x such that every part of x has a proper part and, for any set S of parts of x, there is a set S′ of parts of...

Quantum Mechanics, and apparently its successors, claim that there are minimum quantities by which objects can differ, at least in some situations: electrons can have various “energy levels” in an atom, but to move from one to another they must jump rather than move via continuous variation: and an electron in a hydrogen atom going from -13.6 eV of energy to -3.4 eV does not pass through states of -10eV or -5.1eV, let along -11.1111115637 eV or -4.89712384 eV.

Ockham's razor is popularly phrased as a prohibition against multiplying entities beyond necessity. This prohibition should extend to the receptacle for these entities. To state my thesis more positively and precisely, both qualitative and quantitative parsimony apply to space, time, and possibility. All other things equal, we ought to prefer a hypothesis that postulates less space. Smaller is better. Admittedly, scientists are ambivalent about economizing on the void. They praise simplicity. Yet astronomers have a history of helping themselves to as (...) much empty space as they wish—staggering common sense with the vastness of the universe. This largesse is abetted by an aesthetic bias for sublime hypotheses. Whereas abductions based on beauty converge with parsimony, abductions based on the sublime diverge from parsimony. Awe stifles our inner accountant. Both types of abduction are popular. Both are dubious because we lack independent assurance that the universe is beautiful or sublime. The analogy between space and time supports an extension of parsimony to time. Uniformitarian geologists regarded time as a free resource. However, geologists and cosmologists must justify their postulation of an immense past. Possibility follows suit. Contrary to David Lewis, possible worlds should be minimized. Parsimony about possibilities provides a rationale for parsimony about absences. Absences are possibilities that are not actual. So proliferation of absences entails proliferation of possibilities. We should admit only those absences which do explanatory work. (shrink)

This paper concerns the structure of any spatially extended things, including regions of space or spacetime. I shall use intuitions about the quantity of extended things to argue for a dichotomy: either a given finite extended thing is point-free gunk, that is, it has no points as parts, or it is made of grit, that is there are only finitely many points.

Let us say that an extended object is “composed wholly of simples” just in case it is an aggregate of absolutely unextended parts spread throughout an extended region—that is, just in case there is a set S such that: every member is a point-sized part of the object, and for every x, x is part of the object if and only if it has a part in common with some member of S. Could a truly extended substance be composed entirely (...) of unextended parts? Reflection upon the fact that it must be at least possible for extended objects to touch one another suggests that the answer to this question is: No. (shrink)

In this paper I argue that presentism —the view that only present objects exist—can be motivated, at least to some degree, by virtue of the fact that it is more quantitatively parsimonious than rival views.