Paradoxes, Misc

In [Is Classical Mathematics Appropriate for Theory of Computation?] we show there is a contradiction which in [“Fuzzy Time”, a solution of Unexpected Hanging Paradox (A Fuzzy interpretation of Quantum Mechanics), Philpapers 2019-04-13] we give a solution for that. This is the starting point for new Theories, Theory of Fuzzy Time Computation and Fuzzy Time –Particle interpretation of quantum Mechanics. A question is remained which was mentioned in [Two points and two questions, F.Didehvar, Philpapers, Researchgate, 2025]. Is this contradiction a (...) contradiction in Mathematics too? Here, we try to answer this question. The article belongs to a group of articles which presents the logical back bone of this line of research. (shrink)

The paper explores the alleged connection between indefinite extensibility and the classic paradoxes of Russell, Burali-Forti, and Cantor. It is argued that while indefinite extensibility is not per se a source of paradox, there is a degenerate subspecies—reflexive indefinite extensibility—which is. The result is a threefold distinction in the roles played by indefinite extensibility in generating paradoxes for the notions of ordinal number, cardinal number, and set respectively. Ordinal number, intuitively understood, is a reflexively indefinitely extensible concept. Cardinal number is (...) not. And Set becomes so only in the setting of impredicative higher-order logic—so that Frege’s Basic Law V is guilty at worst of partnership in crime, rather than the sole offender. (shrink)

This chapter is based on the idea that there is an important sense in which the things we say may involve a degree of specificity that goes beyond what we have in mind when we say them. In that sense, the things we say are interpretations of the sentences we use that are sufficiently specific for the purpose of ascribing truth or falsity to those sentences. This chapter explains how the relation between logic and natural language can be elucidated on (...) the basis of this idea, and shows how some fundamental issues concerning vagueness can be handled accordingly. (shrink)

This paper advances The Universal Principle of Collapse (UPC) as a diagnostic method for dissolving paradoxes at inception. By auditing quantum entanglement and nonlocality, it demonstrates that paradoxes do not originate in experiments or mathematics but in language, specifically, in the collapse of metaphor into ontology. Phrases such as “spooky action at a distance” or “instant communication,” even when used ironically, are shown to be linguistic artifacts rather than empirical realities. UPC does not propose new physics or alter quantum formalism. (...) Instead, it reframes paradox as a product of discourse, revealing that paradox ∉ Experiment, paradox ∉ Mathematics, paradox ∈ Language. This recognition dissolves confusion before it coheres, restoring clarity to both scientific and philosophical inquiry. The paper further situates UPC as a bridge between philosophy and quantum mechanics. Language creates coordinate maps of meaning, but when those maps are drawn imprecisely, error propagates across generations of teaching and interpretation. By auditing language against context and intention, UPC collapses error at inception, preventing paradox from becoming legacy. While demonstrated here in the quantum domain, UPC applies wherever metaphor collapses into ontology. In theology, it dissolves paradoxes of faith when metaphor is mistaken for doctrine; in art, it clarifies when symbolism is misread as literal representation; in everyday discourse, it prevents error when figurative speech is taken as fact. Across all domains, UPC functions as a diagnostic principle: paradox dissolves at inception because recognition binds collapse to coherence. (shrink)

This paper, The Quantum Measurement Problem Solved by the Universal Principle of Collapse (UPC), presents UPC as a lens that dissolves paradoxes by restoring the irreducible observer. The Quantum Measurement Problem, often treated as a metaphysical puzzle, is shown to be a linguistic error: mistaking models and equations for reality while excluding the observer they depend upon. Once the observer is restored, the paradox disappears. The structure is deliberate: beginning with transparency, defining UPC, applying it to the Quantum Measurement Problem, (...) extending it to the double‑slit experiment, consciousness, and wider applications. The reasoning is accessible, the principle observable in daily life, and its effect inescapable. UPC dissolves the Quantum Measurement Problem at the level of interpretation by exposing its linguistic collapse and demonstrating its universality across science, philosophy, and ideology. This paper is designed as a concise introduction to UPC. Fuller case studies are available in my published work, noted in the Further Reading section. Its scope is interpretive and philosophical rather than technical physics derivation, and within that frame it delivers exactly as claimed. (shrink)

This paper explores the paradoxical claim “This article is not written by helping AI.” On the one hand, if AI contributes to the drafting process, the claim appears false. On the other hand, if authorship requires semantic intention and responsibility, then the claim may be true even when AI generates text. Drawing on Searle’s Chinese Room, Tarski’s theory of truth, and debates on authorship in philosophy of language, I argue that authorship requires intentionality and responsibility, which AI systems lack. The (...) paradox is resolved by distinguishing between syntactic production and semantic authorship. AI can assist in generating words, but authorship remains a human act of responsibility. -/- (This article is distinctive in nature, and its central problem is: who is the author?) Farzad Didehvar provided an AI system with only a single phrase in Persian, which translates into English as: “This article is not written by Helping AI.” From that seed, the AI generated a complete article in English. The article itself argues—semantically—that it was not written by an AI tool. At the same time, it was not literally written by Farzad either, since he only supplied the initial phrase. This raises a paradoxical question: if the article is neither authored by the AI nor by the human, then who is the true writer? An answer will be provided in the next article, but the author is interested in hearing other opinions. (shrink)

This paper explores the intertwined nature of nothingness, zero, and existence — an inquiry that bridges cosmology, mathematics, and metaphysics. Beginning with the question of whether the universe can ever reach a state of net zero energy, it develops into the articulation of what may be called the Jestin Paradox: any attempt to define absolute nothingness inevitably transforms it into something, because representation itself constitutes information. The paradox reveals that true nothingness cannot exist, as every effort to express or conceive (...) it reintroduces being. Building on this idea, the reflection introduces the Zero Power Hypothesis — the notion that the equilibrium of all potential energies (the zero point) is inherently unstable, leading to spontaneous creation and the emergence of duality. Thus, creation is not the negation of nothingness but its inevitable expression. The essay concludes that the universe is a perpetual ripple of zero failing to remain zero — a dynamic nothingness that sustains all being. (shrink)

This book shows that the assumption that classical logic is essentially a bivalent (i.e., 2-valued) logic, a logic of truth and falsity, is an incorrect and harmful conception. Classical logic is certainly a Boolean logic, and the smallest (non-degenerate) Boolean algebra is the 2-element Boolean algebra; however, there are numerous Boolean algebras that have more than 2 elements, such as the 4-, 8-, 16-, ..., infinite-element Boolean algebra, and they all work equally well for the semantics of classical logic. Contrary (...) to the popular thought, there is such a thing as classical (or Boolean) many-valued logic. The book applies this logic to solve such philosophical problems as the Fission Problem for personal identity, the Sorites Paradox, and the Liar Paradox. All these problems concern situations that involve indeterminacy or vagueness, situations where there seems 'no fact of the matter' that makes the relevant sentences true or false, thus requiring truth value gaps between truth and falsity. Because of that, classical logic has been thought to be an inadequate tool to deal with the problems. This book, however, offers solutions to those problems by retaining classical logic but assigning intermediate Boolean values to the relevant sentences. The book is of great value to researchers and graduate students in philosophy, especially for those who are interested in the philosophical issues surrounding indeterminacy, vagueness, and truth. (shrink)

This work examines the structure of paradoxes, phenomena characterized by the apparent derivation of contradictions or counter-intuitive conclusions from acceptable premises using acceptable reasoning. Motivated by the recurrence of certain features across diverse paradoxes, a specific structural hypothesis regarding their generation is proposed and analyzed. The hypothesis posits that paradoxes frequently arise from the interaction of three components: (1) concepts that establish or interact with boundaries (such as those pertaining to scope, classification, truth, state, or definition); (2) the reflexive application (...) of these concepts or related rules (involving self-reference, self-inclusion, recursion, or causal/definitional circularity); and (3) the involvement of specific operational triggers – negation, limit (including infinity, extremes, or boundary values), or transformation (change of state, identity, position, or logical status) – within the reflexive structure. The study first provides a detailed conceptual analysis of these components – boundaries, reflexivity, and the triggers – outlining their definitions and potential roles based on discussions in logic, philosophy, and related fields. Subsequently, the hypothesis is examined against a wide range of paradoxes drawn from logic, set theory, semantics, physics, metaphysics, epistemology, and decision theory. This examination involves analyzing the structure of each paradox to identify the presence and interaction of the hypothesized components. The analysis indicated a recurrent correspondence between the structures of the examined paradoxes and the proposed pattern involving boundaries, reflexivity, and triggers. Further analysis explored the representation of this structural pattern using elements of logical and mathematical formalism, sketching how the interaction of boundary predicates/sets, reflexive constructions, and operators corresponding to negation, limits, or transformations can lead to derivations of inconsistency (e.g., P ↔ ¬P or P ∧ ¬P) within systems adhering to standard logical principles. The discussion also addressed the context and limitations surrounding the hypothesis, including the meaning of "often arise," the relationship between the identified structure and strategies for paradox resolution (which often involve modifying the system to restrict or manage components of the pattern), the distinction between the structure and its outcome in different systems, and the acknowledgment that the pattern may not be the sole source of all paradoxes and that its identification can involve interpretation. Finally, potential implications arising from the identification of this recurring structure were considered. These include the possibility of providing a unifying framework for paradox analysis across disciplines, offering insights relevant to the design of consistent conceptual and formal systems by highlighting potential points of instability, suggesting connections between the structure and characteristics of natural language or thought involving self-reference and boundary definition, and noting structural resonances with limitative results in mathematical logic, such as Gödel's incompleteness theorems. Potential directions for future work, including further categorization, analysis of non-paradoxical structures, cross-disciplinary applications, and exploration of cognitive aspects, were also outlined. (shrink)

Koons (2014) claims that Benardete’s Grim Reaper Scenario affords grounds for denying that there can be bounded non-well-founded sequences of time intervals. Pruss (2018) claims that Benardete’s Grim Reaper Scenario affords grounds for affirming causal finitism. I shall argue that what you take to be a minimal response to the Benardete scenario is not something that you can arrive at independently from making a determination about whether causal finitism is true and whether there can be bounded non-well-founded sequences of time (...) intervals. In particular, whether you think that the specification of the dispositions of the reapers in Benardete’s scenario is complete depends upon whether or not you think that causal finitism is true. (shrink)

Lewis’s [1968] counterpart theory (LCT for short), motivated by his modal realism, made its appearance within a year of Chisholm’s modal paradox [1967]. We are not modal realists, but we argue that a satisfactory resolution to the paradox calls for a counterpart-theoretic (CT-)semantics. We make our case by showing that the Chandler–Salmon strategy of denying the S4 axiom [◊◊ψ →◊ψ] is inadequate to resolve the paradox – we take on Salmon’s attempts to defend that strategy against objects from Lewis and (...) Williamson. We then consider three substantially different CT-approaches: Lewis’s LCT, Forbes’s (FCT), including his fuzzy version, and Ramachandran’s (RCT). We argue that the best approach is a mish-mash of FCT and RCT. (shrink)

The dogma that the propositional logic of metaphysical modality is S5 is rebutted in related installments (previously published and unpublished essays).

According to Aristotle if a universal proposition (for example: “All men are white”) is true, its contrary proposition (“All men are not white”) must be false; and, according to Aristotle, if a universal proposition (for example: “All men are white”) is true, its contradictory proposition (“Not all men are white”) must be false. I agree with what Aristotle wrote about universal propositions, but there are universal propositions which have no contrary proposition and have no contradictory proposition. The proposition X “All (...) the propositions that contradict this proposition are true” does not have the contrary proposition and does not have the contradictory proposition. In fact: FEX “All the propositions that contradict this proposition are not true” has a different subject: the subject of the proposition X is constituted by all the propositions that contradict the proposition X; by contrast, the subject of the proposition FEX is constituted by all the propositions that contradict the proposition FEX. And FOX “Not all the propositions that contradict this proposition are true” has a different subject: the subject of the proposition X is constituted by the propositions that contradict the proposition X; by contrast, the subject of the proposition FOX is constituted by the propositions that contradict the proposition FOX. According to Aristotle, a singular proposition (in his example: "Socrates is white") which is true must have its negative proposition ("Socrates is not white") which is false. I agree with Aristotle, but there are singular propositions which do not have the corresponding negative proposition. The proposition (or, rather, the pseudo-proposition) L “This same statement is not true” does not have the negative proposition because the proposition FNL “This same statement is true” has a different subject from the subject of the proposition L: the subject of the proposition L is the proposition L; by contrast, the subject of the proposition FNL is the proposition FNL. L and FNL cannot have the same subject. By contrast, the proposition M “This mount is entirely in Swiss territory” and the proposition NM “This mount is not entirely in Swiss territory” can have the same subject (for example, the Mount Eiger): in case the subject of the proposition M and the subject of the proposition NM is the same, M and NM are opposite propositions, NM is the negative proposition of M. By contrast, the proposition (or, rather, the pseudo-proposition) L "This same statement is not true" cannot have the corresponding negative proposition because FNL "This same statement is true" has a different subject: the subject of L is L ; by contrast, the subject of FNL is FNL. Then the paper continues by analyzing some variants of the liar’s paradox: L1 “The statement L1 is not true”; the so-called liar cycle; and the so-called Yablo’s paradox. (shrink)

This chapter addresses the historical influences on Russell’s views in logic and his particular style of symbolic logic. Some credit Gottlob Frege as the main source of Russell’s advocacy of symbolic logic in philosophy and endorsement of logicism, the theory that mathematics reduces to logic. In fact, Russell came to these positions independently, having first discovered modern symbolic logic in the writings of the Italian mathematician Giuseppe Peano and his school. Russell adopted his own notation by modifying theirs, and through (...) it, first became convinced of logicism. He discovered the (mostly earlier) works of Gottlob Frege only later, but Frege’s ideas thereafter became more influential, especially as Russell toiled at solving logical paradoxes and puzzles about meaning hampering his earlier work. Russell’s mature views about philosophical and mathematical logic, propositional functions, classes, logical types, and the theory of meaning, can be seen in many ways as a reaction to the flaws in Frege’s. (shrink)

Logicism is the view that mathematical truths are logical truths. But a logical truth is commonly thought to be one with a universally valid form. The form of “7 > 5” would appear to be the same as “4 > 6”. Yet one is a mathematical truth, and the other not a truth at all. To preserve logicism, we must maintain that the two either are different subforms of the same generic form, or that their forms are not at all (...) what they appear. The historical record shows that Russell pursued both these options, but that the struggle with the logical paradoxes pushed him away from the first kind of response and toward the second. An object cannot itself have a kind of inner logical complexity that makes a proposition have a different logical form merely in virtue of being about it, nor can their representatives in logical forms be single things different for different forms, at least not without postulating too many such objects and thereby creating Cantorian diagonal paradoxes. There are only apparent objects which are actually fragments of logical forms, different in different cases. (shrink)

It is a platitude that when we reason, we often take things for granted, sometimes even justifiably so. The chemist might reason from the fact that a substance turns litmus paper red to that substance being an acid. In so doing, they take for granted, reasonably enough, that this test for acidity is valid. We ordinarily reason from things looking a certain way to their being that way. We take for granted, reasonably enough, that things are as they look Although (...) it is a platitude that we often take things for granted when we reason—whether justifiably or not—one might think that we do not have to. In fact, it is a natural expectation that were we not pressed by time, lack of energy or focus, we could always in principle make explicit in the form of premises every single presupposition we make in the course of our reasoning. In other words, it is natural to expect it to be true that presuppositionless reasoning is possible. In this essay, I argue that it is false: presuppositionless reasoning is impossible. Indeed, I think this is one of the lessons of a long-standing paradox about inference and reasoning known as Lewis Carroll’s (1985) regress of the premises. Many philosophers agree that Carroll’s regress teaches us something foundational about reasoning. I part ways about what it is that it teaches us. What it teaches us is that the structure of reasoning is constitutively presuppositional. (shrink)

In this essay we introduce a new tool for studying the patterns of sentential reference within the framework introduced in [2] and known as the language of paradox $\mathcal {L}_{\mathsf {P}}$ : strong $\mathcal {L}_{\mathsf {P}}$ -homomorphisms. In particular, we show that (i) strong $\mathcal {L}_{\mathsf {P}}$ -homomorphisms between $\mathcal {L}_{\mathsf {P}}$ constructions preserve paradoxicality, (ii) many (but not all) earlier results regarding the paradoxicality of $\mathcal {L}_{\mathsf {P}}$ constructions can be recast as special cases of our central result regarding (...) strong $\mathcal {L}_{\mathsf {P}}$ -homomorphisms, and (iii) that we can use strong $\mathcal {L}_{\mathsf { P}}$ -homomorphisms to provide a simple demonstration of the paradoxical nature of a well-known paradox that has not received much attention in this context: the McGee paradox. In addition, along the way we will highlight how strong $\mathcal {L}_{\mathsf {P}}$ -homomorphisms highlight novel connections between the graph-theoretic analyses of paradoxes mobilized in the $\mathcal {L}_{\mathsf {P}}$ framework and the methods and tools of category theory. (shrink)

According to the revision theory of truth, the binary sequences generated by the paradoxical sentences in revision sequence are always unstable. In this paper, we work backwards, trying to reconstruct the paradoxical sentences from some of their binary sequences. We give a general procedure of constructing paradoxes with specific binary sequences through some typical examples. Particularly, we construct what Herzberger called “unstable statements with unpredictably complicated variations in truth value.” Besides, we also construct those paradoxes with infinitely many finite primary (...) periods but without any infinite primary period, those with an infinite critical point but without any finite primary period, and so on. This is the first formal appearance of these paradoxes. Our construction demonstrates that the binary sequences generated by a paradoxical sentence are something like genes from which we can even rebuild the original sentence itself. (shrink)

Although formal analysis provides us with interesting tools for treating Curry’s paradox, it certainly does not exhaust every possible reading of it. Thus, we suggest that this paradox should be analysed with non-formal tools coming from pragmatics. In this way, using Grice’s logic of conversation, we will see that Curry’s sentence can be reinterpreted as a peculiar conditional sentence implying its own consequent.

Morgenbesser's Coin is a thought experiment that exemplifies a widespread disposition to infer counterfactual independence from causal independence. I argue that this disposition is mistaken by analysing a closely related thought experiment.

در تکوین نظریه محاسبات از اوایل قرن بیستم پارادکسها و خود ارجاعی نقش ویژه ای را بازی کرده اند. هر چند نظریه محاسبات عام بر اساس تعریف ماشین تورینگ، فرض تورینگ_چرچ و کاربردهای آن بنا شده ،اما از همان ابتدا تا به امروز منطق و حوزه های مختلف این علم در ارتباط تنگاتنگ با این تیوری و در ابتدا نظریه محاسبات خاص بوده و این ارتباط روز به روز گسترده و گسترده تر گشته است. از تاثیر پارادوکس دروغگو و پارادکس (...) بری در تمایز میان مفهوم محاسبه پذیر و محاسبه پذیر شمارایانه، قضایای گودل و قضیه چیتین همه جا شاهد این تاثیر و تاثر متقابل هستیم. در این مقال می خواهیم بعد از معرفی اجمالی مطالب باال، تاثیر یک پارادوکس دیگر، پارادوکس اعدام غیر منتظره، را بر این نظریه بررسی نماییم. (shrink)

The Nothing from Infinity paradox arises when the combination of two infinitudes of point particles meet in a supertask and disappear. Corral-Villate claims that my arguments for disappearance fail and concedes that this failure also produces an extreme kind of indeterminism, which I have called plenitudinous. So my supertask at least poses a dilemma of extreme indeterminism within Newtonian point particle mechanics. Plenitudinous indeterminism might be trivial, although easy attempts to prove it so seem to fail in the face of (...) plausible continuity principles. However, the question of its triviality is here moot, since I show that, except in one case, Corral-Villate’s disproofs fail, and with a correction, the original arguments are unrefuted. Consequently, of the two contenders for the outcome of my supertask, the Nothing from Infinity paradox has won out. (shrink)

Richard Heck has recently drawn attention on a new version of the Liar Paradox, one which relies on logical resources that are so weak as to suggest that it may not admit of any ‘‘truly satisfying, consistent solution’’. I argue that this conclusion is too strong. Heck’s Liar reduces to absurdity principles that are already rejected by consistent paracomplete theories of truth, such as Kripke’s and Field’s. Moreover, the new Liar gives us no reasons to think that (versions of) these (...) principles cannot be consistently retained once the structural rule of contraction is restricted. I suggest that revisionary logicians have independent reasons for restricting such a rule. (shrink)

Several authors have investigated the question of whether canonical logic-based accounts of belief revision, and especially the theory of AGM revision operators, are compatible with the dynamics of Bayesian conditioning. Here we show that Leitgeb's stability rule for acceptance, which has been offered as a possible solution to the Lottery paradox, allows to bridge AGM revision and Bayesian update: using the stability rule, we prove that AGM revision operators emerge from Bayesian conditioning by an application of the principle of maximum (...) entropy. In situations of information loss, or whenever the agent relies on a qualitative description of her information state - such as a plausibility ranking over hypotheses, or a belief set - the dynamics of AGM belief revision are compatible with Bayesian conditioning; indeed, through the maximum entropy principle, conditioning naturally generated AGM revision operators. This mitigates an impossibility theorem of Lin and Kelly for tracking Bayesian conditioning with AGM revision, and suggests an approach to the compatibility problem that highlights the information loss incurred by acceptance rules in passing from probabilistic to qualitative representations of beliefs. (shrink)

Bertrand’s paradox ) can be considered as a cautionary memento, to practitioners and students of probability calculus alike, of the possible ambiguous meaning of the term ‘at random’ when the sample space of events is continuous. It deals with the existence of different possible answers to the following question: what is the probability that a chord, drawn at random in a circle of radius R, is longer than the side of an inscribed equilateral triangle? Physics can help to remove the (...) ambiguity by identifying an actual experiment, whose outcome is obviously unique and prescribes the physical variables to which the term ‘random’ can be correctly applied. In this paper, after briefly describing Bertrand’s paradox, we associate it with an experiment, which is basically a variation of the famous Buffon’s needle experiment for estimating the value of π. Its outcome is compared with the analytic predictions of probability calculus, that is with the probability distribution of variables whose uniform distribution can be considered a sound implementation of complete randomness. (shrink)

This paper introduces two new paradoxes for standard deontic logic (SDL). They are importantly related to, but distinct from Ross' paradox. These two new paradoxes for SDL are the simple weakening paradox and the complex weakening paradox. Both of these paradoxes arise in virtue of the underlaying logic of SDL and are consequences of the fact that SDL incorporates the principle known as weakening. These two paradoxes then show that SDL has counter-intuitive implications related to disjunctive obligations that arise in (...) virtue of deontic weakening and in virtue of decisions concerning how to discharge such disjunctive obligations. The main result here is then that theorem T1 is a problematic component of SDL that needs to be addressed. (shrink)

Thought experiments are common where infinitely many entities acting in concert give rise to strange results. A contemporary family of these thought experiments have been labeled “New Zeno” cases. These cases, however, can be generalized to ensure almost any outcome from systems with limited materials. Consider an infinite series of clowns, with iron wills and instantaneous balloon-placing powers. The chapter argues that, given New Zeno assumptions, as well as ensuring things like balloons appearing without any clown placing them, they can (...) ensure the existence of mountains of ice cream or even the movement of galaxies. Reflection on these cases helps bring out what is so troubling about New Zeno cases, and raise again the specter that there is something impossible about actual physical infinites of this sort. (shrink)

We present a revenge argument for non-reflexive theories of semantic notions – theories which restrict the rule of assumption, or initial sequents of the form φ ⊩ φ. Our strategy follows the general template articulated in Murzi and Rossi [21]: we proceed via the definition of a notion of paradoxicality for non-reflexive theories which in turn breeds paradoxes that standard non-reflexive theories are unable to block.

In the literature on self-referential paradoxes one of the hardest and most challenging problems is that of revenge. This problem can take many shapes, but, typically, it besets non-classical accounts of some semantic notion, such as truth, that depend on a set of classically defined meta-theoretic concepts, like validity, consistency, and so on. A particularly troubling form of revenge that has received a lot of attention lately involves the concept of validity. The difficulty lies in that the non-classical logician cannot (...) accept her own definition of validity because it is given in a classical meta-theory. It is often suggested that this mismatch between the consequence relation of the account being espoused and the consequence relation of the meta-theory is a serious embarrassment. The main goal of the paper is to explore whether certain substructural accounts of the paradoxes can avoid this sort of embarrassment. Typically, these accounts are expressively incomplete, since they cannot assert in the object language that certain invalid arguments are in fact invalid. To overcome this difficulty I develop a novel type of hybrid proof-procedure, one that takes invalidities to be just as fundamental as validities. I prove that this proof-procedure enjoys a number of interesting properties and I analyze the prospects of applying it to languages capable of expressing self-referential statements. (shrink)

The aim of this volume is to open up new perspectives and to raise new research questions about a unified approach to truth, modalities, and propositional attitudes. The volume's essays are grouped thematically around different research questions. The first theme concerns the tension between the theoretical role of the truth predicate in semantics and its expressive function in language. The second theme of the volume concerns the interaction of truth with modal and doxastic notions. The third theme covers higher-order solutions (...) to the semantic and modal paradoxes, providing an alternative to first-order solutions embraced in the first two themes. This book will be of interest to researchers working in epistemology, logic, philosophy of logic, philosophy of language, philosophy of mathematics, and semantics. (shrink)

The unwinding that Cook, 767–774 2004) proposed is a simple but powerful method of generating new paradoxes from known ones. This paper extends Cook’s unwinding to a larger class of paradoxes and studies further the basic properties of the unwinding. The unwinding we study is a procedure, by which when inputting a Boolean modal net together with a definable digraph, we get a set of sentences in which we have a ‘counterpart’ for each sentence of the Boolean modal net and (...) each point of the digraph. What is more, whenever a sentence of the Boolean modal net says another sentence is necessary, then the counterpart of the first sentence at a point correspondingly says the counterparts of the second one at all accessible points of that point are all true. The output of the procedure is called ‘the unwinding of a Boolean modal net on a definable digraph’. We prove that the unwinding procedure preserves paradoxicality: a Boolean modal net is paradoxical on a definable digraph, iff the unwinding of it on this digraph is also paradoxical. Besides, the dependence digraph for the unwinding of a Boolean modal net on a definable digraph is proved to be isomorphic to the unwinding of the dependence digraph for the Boolean modal net on the previous definable digraph. So the unwinding of a Boolean modal net on a digraph is self-referential, iff the Boolean modal net is self-referential and the digraph is cyclic. Thus, on the one hand, the unwinding of any Boolean modal net on an acyclic digraph is non-self-referential. In particular, the unwinding of any Boolean modal net on \ is non-self-referential. On the other hand, if a Boolean modal net is paradoxical on a locally finite digraph, the unwinding of it on that digraph must be self-referential. Hence, starting from a Boolean modal paradox, the unwinding can output a non-self-referential paradox only if the digraph is not locally finite. (shrink)

In this paper, I examine the deep theological faultline generated by divergent understandings of the divine attributes among two early antagonistic Muslim groups – the traditionalists (main...

A new computational methodology allowing one to work in a new way with infinities and infinitesimals is presented in this paper. The new approach, among other things, gives the possibility to calculate the number of elements of certain infinite sets, avoids indeterminate forms and various kinds of divergences. This methodology has been used by the author as a starting point in developing a new kind of computer – the Infinity Computer – able to execute computations and to store in its (...) memory not only finite numbers but also infinite and infinitesimal ones. (shrink)

A computational methodology called Grossone Infinity Computing introduced with the intention to allow one to work with infinities and infinitesimals numerically has been applied recently to a number of problems in numerical mathematics (optimization, numerical differentiation, numerical algorithms for solving ODEs, etc.). The possibility to use a specially developed computational device called the Infinity Computer (patented in USA and EU) for working with infinite and infinitesimal numbers numerically gives an additional advantage to this approach in comparison with traditional methodologies studying (...) infinities and infinitesimals only symbolically. The grossone methodology uses the Euclid’s Common Notion no. 5 ‘The whole is greater than the part’ and applies it to finite, infinite, and infinitesimal quantities and to finite and infinite sets and processes. It does not contradict Cantor’s and non-standard analysis views on infinity and can be considered as an applied development of their ideas. In this paper we consider infinite series and a particular attention is dedicated to divergent series with alternate signs. The Riemann series theorem states that conditionally convergent series can be rearranged in such a way that they either diverge or converge to an arbitrary real number. It is shown here that Riemann’s result is a consequence of the fact that symbol ∞ used traditionally does not allow us to express quantitatively the number of addends in the series, in other words, it just shows that the number of summands is infinite and does not allows us to count them. The usage of the grossone methodology allows us to see that (as it happens in the case where the number of addends is finite) rearrangements do not change the result for any sum with a fixed infinite number of summands. There are considered some traditional summation techniques such as Ramanujan summation producing results where to divergent series containing infinitely many positive integers negative results are assigned. It is shown that the careful counting of the number of addends in infinite series allows us to avoid this kind of results if grossone-based numerals are used. (shrink)

An important suggestion of objective Bayesians is that the maximum entropy principle can replace a principle which is known to get into paradoxical difficulties: the principle of indifference. No one has previously determined whether the maximum entropy principle is better able to solve Bertrand’s chord paradox than the principle of indifference. In this paper I show that it is not. Additionally, the course of the analysis brings to light a new paradox, a revenge paradox of the chords, that is unique (...) to the maximum entropy principle. (shrink)

Systems ofillative logicare logical calculi formulated in the untypedλ-calculus supplemented with certain logical constants.1In this short paper, I consider a paradox that arises in illative logic. I note two prima facie attractive ways of resolving the paradox. The first is well known to be consistent, and I briefly outline a now standard construction used by Scott and Aczel that establishes this. The second, however, has been thought to be inconsistent. I show that this isn’t so, by providing a nonempty class (...) of models that establishes its consistency. I then provide an illative logic which is sound and complete for this class of models. I close by briefly noting some attractive features of the second resolution of this paradox. (shrink)

In this paper, we axiomatize the deontic logic in Fusco (2015), which uses a Stalnaker-inspired account of diagonal acceptance and a two-dimensional account of disjunction to treat Ross’s Paradox and the Puzzle of Free Choice Permission. On this account, disjunction-involving validities are a priori rather than necessary. We show how to axiomatize two-dimensional disjunction so that the introduction/elimination rules for boolean disjunction can be viewed as one-dimensional projections of more general two-dimensional rules. These completeness results help make explicit the restrictions (...) Fusco’s account must place on free-choice inferences. They are also of independent interest, as they raise difficult questions about how to “lift” a Kripke frame for a one-dimensional modal logic into two dimensions. (shrink)

It seems that the most common strategy to solve the liar paradox is to argue that liar sentences are meaningless and, consequently, truth-valueless. The other main option that has grown in recent years is the dialetheist view that treats liar sentences as meaningful, truth-apt and true. In this paper I will offer a new approach that does not belong in either camp. I hope to show that liar sentences can be interpreted as meaningful, truth-apt and false, but without engendering any (...) contradiction. This seemingly impossible task can be accomplished once the semantic structure of the liar sentence is unpacked by a quantified analysis. The paper will be divided into two sections. In the first section, I present the independent reasons that motivate the quantificational strategy and how it works in the liar sentence. In the second section, I explain how this quantificational analysis allows us to explain the truth teller sentence and a counter-example advanced against truthmaker maximalism, and deal with some potential objections. (shrink)

This paper explores the relationship borne by the traditional paradoxes of set theory and semantics to formal incompleteness phenomena. A central tool is the application of the Arithmetized Completeness Theorem to systems of second-order arithmetic and set theory in which various “paradoxical notions” for first-order languages can be formalized. I will first discuss the setting in which this result was originally presented by Hilbert & Bernays (1939) and also how it was later adapted by Kreisel (1950) and Wang (1955) in (...) order to obtain formal undecidability results. A generalization of this method will then be presented whereby Russell’s paradox, a variant of Mirimanoff’s paradox, the Liar, and the Grelling–Nelson paradox may be uniformly transformed into incompleteness theorems. Some additional observations are then framed relating these results to the unification of the set theoretic and semantic paradoxes, the intensionality of arithmetization (in the sense of Feferman, 1960), and axiomatic theories of truth. (shrink)

I was invited to contribute this short piece to a book published in Russia, consisting of brief statements on the nature of morality written by approximately 90 scholars. Each essay is published in both English and Russian. My essay offers my considered answer to the question posed in the title, though in the end all contributions were published without titles.

An eternal society with the abilities of ordinary humans in each year of its existence would have had the ability to actualize a logical contradiction. This fact casts doubt on the metaphysical possibility of an infinite past. In addition to using this paradox in an argument against an infinite past, one can also use the paradox mutatis mutandis as a decisive argument against the sempiternality of God.

The strict-tolerant approach to paradox promises to erect theories of naïve truth and tolerant vagueness on the firm bedrock of classical logic. We assess the extent to which this claim is founded. Building on some results by Girard we show that the usual proof-theoretic formulation of propositional ST in terms of the classical sequent calculus without primitive Cut is incomplete with respect to ST-valid metainferences, and exhibit a complete calculus for the same class of metainferences. We also argue that the (...) latter calculus, far from coinciding with classical logic, is a close kin of Priest’s LP. (shrink)

This anthology contains revised versions of selected papers presented at the fourth bi-annual international deontic logic conference, DEON’98. This volume includes our substantial introduction, and an article from me as a contributor. The volume includes papers from all four distinguished invited speakers, David Makinson, Donald Nute, Claudio Pizzi, and the founder of deontic logic, Georg Von Wright. Other notables among the authors are Dov Gabbay (co-editor of the Handbook on Philosophical Logic vols.1-4, and editor of a number of logic book (...) series); Lars Lindahl (author of Position and Change: A Study in Law and Logic); Andrew Jones (past editor of the Norwegian Journal of Philosophical Logic, and the co-author of the entry “Deontic Logic and Contrary-to-Duties” in the 2nd edition of Handbook on Philosophical Logic); and Marek Sergot (a leading researcher at the interface of deontic logic and computer science.). (shrink)