-
204894.515088
Two problems are investigated. Why is it that in his solutions to logical problems, Boole’s logical/numerical operations can be difficult to pin down, and why did his late manuscript attempt to get rid of division by zero fall short of that goal? It is suggested that the former is due to different readings that he gives to the operations according to the stage of the solution routine, and the latter is due to a strict confinement to equational reasoning.
-
204914.515172
Ancient formulations of the distinction between continuous and separative hypotheticals, made by Peripatetics working under Stoic influence, can be vague and confusing. Perhaps the clearest expositor of the matter was Galen. We review his account, provide two formal articulations of it, verify their equivalence, and show that for what we call ‘simple’ hypotheticals, the formal line of demarcation is independent of whether or not modality is taken into account.
-
379111.51519
We furnish a core-logical development of the Gödel numbering framework that allows metamathematicians to attain limitative results about arithmetical truth without incorporating a genuine truth predicate into the language in a way that would lead to semantic closure. We show how Tarski’s celebrated theorem on the arithmetical undefinability of arithmetical truth can be established using only core logic in both the object language and the metalanguage. We do so at a high level of abstraction, by augmenting the usual first-order language of arithmetic with a primitive predicate Tr and then showing how it cannot be a truth predicate for the augmented language. McGee established an important result about consistent theories that are in the language of arithmetic augmented by such a “truth predicate” Tr and that use Gödel numbering to refer to expressions of the augmented language. Given the nature of his sought result, he was forced to use classical reasoning at the meta level. He did so, however, on the additional and tacit presupposition that the arithmetical theories in question (in the object language) would be closed under classical logic. That left open the dialectical possibility that a constructivist (or intuitionist) could claim not to be discomfited by the results, even if they were to “give a pass” on the unavoidably classical reasoning at the meta level. In this study we “constructivize” McGee’s result, by presuming only core logic for the object language. This shows that the perplexity induced by McGee’s result will confront the constructivist (or intuitionist) as well.
-
379132.515201
Berry’s Paradox, like Russell’s Paradox, is a ‘paradox’ in name only. It differs from genuine logico-semantic paradoxes such as the Liar Paradox, Grelling’s Paradox, the Postcard Paradox, Yablo’s Paradox, the Knower Paradox, Prior’s Intensional Paradoxes, and their ilk. These latter arise from semantic closure. Their genuine paradoxicality manifests itself as the non-normalizability of the formal proofs or disproofs associated with them. The Russell, the Berry, and the Burali-Forti ‘paradoxes’, by contrast, simply reveal the straightforward inconsistency of their respective existential claims—that the Russell set exists; that the Berry number exists; and that the ordinal of the well-ordering of all ordinals exists. The disproofs of these existential claims are in free logic and are in normal form. They show that certain complex singular terms do not—indeed, cannot—denote. All this counsels reconsideration of Ramsey’s famous division of paradoxes and contradictions into his Group A and Group B. The proof-theoretic criterion of genuine paradoxicality formally explicates an informal and occasionally confused notion. The criterion should be allowed to reform our intuitions about what makes for genuine paradoxicality, as opposed to straightforward (albeit surprising) inconsistency.
-
559018.515211
A critique is given of the attempt by Hettema and Kuipers to formalize the periodic table. In particular I dispute their notions of identifying a naïve periodic table with tables having a constant periodicity of eight elements and their views on the different conceptions of the atom by chemists and physicists. The views of Hettema and Kuipers on the reduction of the periodic system to atomic physics are also considered critically.
-
1350962.515223
In this short note, which is the final chapter of the volume 60 Years of Connexive Logic, we list ten open problems. Some of these problems are technical and precisely stated, while others are less technical and even speculative. We hope that the list inspires some readers to contribute to the field by tackling one or many of the problems.
-
1350984.515234
The present article aims at generalizing the approach to connexive logic that was initiated in [27], by following the work by Paul Egré and Guy Politzer. To this end, a variant of the connexive modal logic CK is introduced and some basic results including soundness and completeness results are established. A tableau calculus is also presented in an appendix.
-
1410836.515244
This paper investigates two forms of the Routley star operation, one in Routley & Routley 1972 and the other in Leitgeb 2019. We use object theory (OT) to define both forms and show that in OT’s hyperintensional logic, (a) the two forms aren’t equivalent, but (b) become equivalent under certain conditions. We verify our definitions by showing that the principles governing both forms become derivable and need not be stipulated. Since no mathematics is assumed in OT, the existence of the Routley star image s of a situation s is therefore guaranteed not by set theory but by a theory of abstract objects. The work in the paper integrates Routley star into a more general theory of (partial) situations that has previously been used to develop the theory of possible worlds and impossible worlds.
-
1424383.515254
In this paper, we provide an axiom system for the relevant logic of equivalence relation frames and prove completeness for it. This provides a partial answer to the longstanding open problem of axiomatizing frames for relevant modal logics where the modal accessibility relation is symmetric. Following this, we show that the logic enjoys Hallden completeness and that a related logic enjoys the disjunction property.
-
1748925.515264
It is shown that one common formulation of Stalnaker’s semantics for conditionals is incomplete: it has no sound and (strongly) complete proof system. At first, this seems to conflict with well-known completeness results for this semantics (e.g., Stalnaker and Thomason 1967, Stalnaker 1970 and Lewis 1973, ch. 6). As it turns out, it does not: these completeness results rely on another closely-related formulation of the semantics that is provably complete. Specifically, the difference comes down to how the Limit Assumption is stated. I close with some remarks about what this means for the logic of conditionals.
-
2107905.515274
1. Strong and weak notions of erasure are distinguished according to whether the single erasure procedure does or does not leave the environment in the same state independently of the pre-erasure state. 2. Purely thermodynamic considerations show that strong erasure cannot be dissipationless. 3. The main source of entropy creation in erasure processes at molecular scales is the entropy that must be created to suppress thermal fluctuations (“noise”). 4. A phase space analysis recovers no minimum entropy cost for weak erasure and a positive minimum entropy cost for strong erasure. 5. An information entropy term has been attributed mistakenly to pre-erasure states in the Gibbs formalism through the neglect of an additive constant in the “–k sum p log p” Gibbs entropy formula.
-
2157591.515283
The inference pattern known as disjunctive syllogism (DS) appears as a derived rule in Gentzen’s natural deduction calculi NI and NK. This is a paradoxical feature of Gentzen’s calculi in so far as DS is sometimes thought of as appearing intuitively more elementary than the rules ∨E, ¬E, and EFQ that figure in its derivation. For this reason, many contemporary presentations of natural deduction depart from Gentzen and include DS as a primitive rule. However, such departures violate the spirit of natural deduction, according to which primitive rules are meant to relationally define logical connectives via universal properties (§2). This situation raises the question: Can disjunction be relationally defined with DS instead of with Gentzen’s ∨I and ∨E rules? We answer this question in the affirmative and explore the duality between Gentzen’s definition and our own (§3). We argue further that the two universal characterizations, rather than provide competing relational definitions of a single disjunction operator, disambiguate natural language’s “or” (§4). Finally, this disambiguation is shown to correspond exactly with the additive and multiplicative disjunctions of linear logic (§5). The hope is that this analysis sheds new light on the latter connective, so often deemed mysterious in writing about linear logic.
-
2174223.515293
If the philosophy of mathematics wants to be rigorous, the concept of infinity must stop being equivocal (both potential and actual) as it currently is. The conception of infinity as actual is responsible for all the paradoxes that compromise the very foundation of mathematics and is also the basis on which Cantor's argument is based on the non-countability of R, and the existence of infinite cardinals of different magnitude. Here we present proof that all infinite sets (in a potential sense) are countable and that there are no infinite cardinals.
-
2231892.515304
The philosophical literature on mathematical structuralism and its history has focused on the emergence of structuralism in the 19th century. Yet modern abstractionist accounts cannot provide an historical account for the abstraction process. This paper will examine the role of relations in the history of mathematics, focusing on three main epochs where relational abstraction is most prominent: ancient Greek, 17th and 19th centuries, to provide a philosophical account for the abstraction of structures. Though these structures emerged in the 19th century with definitional axioms, the need for such axioms in the abstraction process comes about, as this paper will show, after a series of relational abstractions without a suitable basis.
-
2347380.515315
This article concerns various foundational aspects of the periodic system of the elements. These issues include the dual nature of the concept of an “element” to include element as a “basic substance” and as a “simple substance.” We will discuss the question of whether there is an optimal form of the periodic table, including whether the left-step table fulfils this role. We will also discuss the derivation or explanation of the [n ⫹ ᐉ , n] or Madelung rule for electron-shell filling and whether indeed it is important to attempt to derive this rule from first principles. In particular, we examine the views of two chemists, Henry Bent and Eugen Schwarz, who have independently addressed many of these issues.
-
2924389.515326
This paper is about a problem which arose in mathematics but is now widely considered by mathematicians to be a matter “merely” for philosophy. I want to show what philosophy can contribute to solving the problem by returning it to mathematics, and I will do that by elucidating what it is to be a solution to a mathematical problem at all.
-
3036597.515334
Angelic visitations in our world are at best rare, and at worst they never occur at all. Not so in Neil Fisk’s world. There, angelic visitations are common – and often deadly. Neil lost his wife to such a visitation, and he’s hated God ever since. The problem with this hatred is that Neil is quite sure his wife is in heaven, as he saw her soul ascending and has never seen her walking around in hell during the frequent glimpses the living are given of the underworld. Since Neil thinks he cannot willingly become devout, he must rely on a divine glitch; those who are caught in heaven’s light during an angelic visitation involuntarily become devout, and thus go to heaven. Luckily for Neil, he drives into a beam of heaven’s light, loses his sight, and becomes devout. Unluckily for Neil, God sends him to hell anyway.
-
3039703.515345
The article summarizes the present state of research into the conceptual foundations of the periodic table. We give a brief historical account of the development of the periodic table and periodic system, including the impact of modern physics due to the discoveries of Moseley, Bohr, modern quantum mechanics etc. The role of the periodic table in the debate over the reduction of chemistry is discussed, including the attempts to derive the Madelung rule from first principles. Other current debates concern the concept of an “element” and its dual role as simple substance and elementary substance and the question of whether elements and groups of elements constitute natural kinds. The second of these issues bears on the question of further debates concerning the placement of certain elements like H, He, La and Ac in the periodic table.
-
3041186.515356
Discussions on the compositionality of inferential roles concentrate on extralogical vocabulary. However, there are nontrivial problems concerning the compositionality of sentences formed by the standard constants of propositional logic. For example, is the inferential role of AB uniquely determined by those of A and B? And how is it determined? This paper investigates such questions. We also show that these issues raise matters of more significance than may prima facie appear.
-
3359824.515364
laying down a program for this study. It is written for everyone who is curious about the world of symbols that surrounds us, in particular researchers and students in philosophy, history, cognitive science, and mathematics education. The main characteristics of mathematical notations are introduced and discussed in relation to the intended subject matter, the language in which the notations are verbalized, the cognitive resources needed for learning and understanding them, the tasks that they are used for, their material basis, and the historical context in which they are situated. Specific criteria for the design and assessment of notations are discussed, as well as ontological, epistemological, and methodological questions that arise from the study of mathematical notations and of their use in mathematical practice.
-
3442567.515376
While the traditional conception of inductive logic is Carnapian, I develop a Peircean alternative and use it to unify formal learning theory, statistics, and a significant part of machine learning: supervised learning. Some crucial standards for evaluating non-deductive inferences have been assumed separately in those areas, but can actually be justified by a unifying principle.
-
3496765.515385
Incurvati and Schlöder (Journal of Philosophical Logic, 51(6), 1549–1582, 2022) have recently proposed to define supervaluationist logic in a multilateral framework, and claimed that this defuses well-known objections concerning supervaluationism’s apparent departures from classical logic. However, we note that the unconventional multilateral syntax prevents a straightforward comparison of inference rules of different levels, across multi- and unilateral languages. This leaves it unclear how the supervaluationist multilateral logics actually relate to classical logic, and raises questions about Incurvati and Schlöder’s response to the objections. We overcome the obstacle, by developing a general method for comparisons of strength between multi-and unilateral logics. We apply it to establish precisely on which inferential levels the supervaluationist multilateral logics defined by Incurvati and Schlöder are classical. Furthermore, we prove general limits on how classical a multilateral logic can be while remaining supervaluationistically acceptable. Multilateral supervaluationism leads to sentential logic being classical on the levels of theorems and regular inferences, but necessarily strictly weaker on meta- and higher-levels, while in a first-order language with identity, even some classical theorems and inferences must be forfeited. Moreover, the results allow us to fill in the gaps of Incurvati and Schlöder’s strategy for defusing the relevant objections.
-
3558894.515396
I would like to begin this review by stating that this is an absolutely wonderful book that is full of gems about the elements and the periodic table. In my own 2007 book on the periodic table I concluded that we should perhaps think of the variety of tables that have appeared as spanning a spectrum running from the most abstract and ‘perfect’ tables such as Janet’s left-step table representation, to the unruly tables that emphasize the uniqueness of elements. To illustrate the latter category, I featured an image of Rayner-Canham’s table that is also the table shown on the front cover of his new book now under review. Rayner Canham’s book is all about the individuality of elements and how so many of the commonly held trends in the periodic table are far more complicated than we normally acknowledge.
-
3558914.515406
In this paper, we introduce a concept of non-dependence of variables in formulas. A formula in first-order logic is non-dependent of a variable if the truth value of this formula does not depend on the value of that variable. This variable non-dependence can be subject to constraints on the value of some variables which appear in the formula, these constraints are expressed by another first-order formula. After investigating its basic properties, we apply this concept to simplify convoluted formulas by bringing out and discarding redundant nested quantifiers. Such convoluted formulas typically appear when one uses a translation function interpreting a theory into another.
-
3789670.515417
This paper introduces a digital method for analyzing propositional logical equivalences. It transforms the theorem-proof method from the complex statement-derivation method to a simple number-comparison method. By applying the digital calculation method and the expression-number lookup table, we can quickly and directly discover and prove logical equivalences based on the identical numbers, no additional operations are needed. This approach demonstrates significant advantages over the conventional methods in terms of simplicity and efficiency.
-
3898740.515428
It has been a long day and you are making your way through a paper related to your work. You suddenly come across the following remark: “. . . since ? and ? are eigenvectors of ? with distinct eigenvalues, they are linearly independent.” Wait—how does the proof go? You should really know this. Here ? and ? are nonzero elements of a vector space ? and ? ∶ ? → ? is a linear map. You force yourself to pick up a pen and write down the following argument: Let ?(?) = ?? and ?(?) = ?? with ? ≠ ?. Suppose ?? + ?? = 0. Applying ? and using linearity, we have ??? + ??? = 0. Multiplying the original equation by ?, we have ??? + ??? = 0. Subtracting the two yields (? − ?)?? = 0 and since ? − ? and ? are nonzero, we have ? = 0. The corresponding argument with ? and ? swapped yields ? = 0, so the only linear combination of ? and ? that yields is the trivial one.
-
3960928.515438
This paper develops the model theory of normal modal logics based on partial “possibilities” instead of total “worlds,” following Humber-stone [1981] instead of Kripke [1963]. Possibility semantics can be seen as extending to modal logic the semantics for classical logic used in weak forcing in set theory, or as semanticizing a negative translation of classical modal logic into intuitionistic modal logic. Thus, possibility frames are based on posets with accessibility relations, like intuitionistic modal frames, but with the constraint that the interpretation of every formula is a regular open set in the Alexandrov topology on the poset. The standard world frames for modal logic are the special case of possibility frames wherein the poset is discrete. The analogues of classical Kripke frames, i.e., full world frames, are full possibility frames, in which propositional variables may be interpreted as any regular open sets. We develop the beginnings of duality theory, definability and correspondence theory, and completeness theory for possibility frames. The duality theory, relating possibility frames to Boolean algebras with operators (BAOs), shows the way in which full possibility frames are a generalization of Kripke frames. Whereas Thomason [1975a] Previous versions of this article circulated online as the working papers Holliday 2015, Holliday 2016, and Holliday 2018. The present version updates Holliday 2018 based on the review process for The Australasian Journal of Logic.
-
3964232.515448
We consider the following question: how close to the ancestral root of a phylogenetic tree is the most recent common ancestor of k species randomly sampled from the tips of the tree? For trees having shapes predicted by the Yule–Harding model, it is known that the most recent common ancestor is likely to be close to (or equal to) the root of the full tree, even as n becomes large (for k fixed). However, this result does not extend to models of tree shape that more closely describe phylogenies encountered in evolutionary biology. We investigate the impact of tree shape (via the Aldous β−splitting model) to predict the number of edges that separate the most recent common ancestor of a random sample of k tip species and the root of the parent tree they are sampled from. Both exact and asymptotic results are presented. We also briefly consider a variation of the process in which a random number of tip species are sampled.
-
4078092.515468
We rigorously describe the relation in which a credence function should stand to a set of chance functions in order for these to be compatible in the way mandated by the Principal Principle. This resolves an apparent contradiction in the literature, by means of providing a formal way of combining credences with modest chance functions so that the latter indeed serve as guides for the former. Along the way we note some problematic consequences of taking admissibility to imply requirements involving probabilistic independence. We also argue, contra [12], that the Principal Principle does not imply the Principal of Indifference.
-
4121288.515478
We study Doob’s Consistency Theorem and Freedman’s Inconsistency Theorem from the vantage point of computable probability and algorithmic randomness. We show that the Schnorr random elements of the parameter space are computably consistent, when there is a map from the sample space to the parameter space satisfying many of the same properties as limiting relative frequencies. We show that the generic inconsistency in Freedman’s Theorem is effectively generic, which implies the existence of computable parameters which are not computably consistent. Taken together, this work provides a computability-theoretic solution to Diaconis and Freedman’s problem of “know[ing] for which [parameters] θ the rule [Bayes’ rule] is consistent” ([DF86, 4]), and it strengthens recent similar results of Takahashi [Tak23] on Martin-Lof randomness in Cantor space.