Susanne Bobzien

This chapter offers a revenge-free solution to the liar paradox and presents a formal representation of truth in, or for, a natural language like English, which proposes to show both why (and how) truth is coherent and how it appears to be incoherent, while preserving classical logic and most principles that some philosophers have taken to be central to the concept of truth and our use of that notion. The chapter argues that, by using a truth operator rather than truth predicate, it is possible to provide a coherent, model-theoretic representation of truth with various desirable features. After investigating what features of liar sentences are responsible for their paradoxicality, the chapter identifies the logic as the normal modal logic KT4M. Drawing on the structure of KT4M, the author proposes that, pace _deflationism_, truth has content, that the content of truth is bivalence, and that the notions of both truth and bivalence are semideterminable.

This chapter is an exercise in the study of philosophical reception, and also serves as an introduction to the reception of the _Nicomachean Ethics_ from its beginnings to the present day. Rather than researching the reception of an author, book, chapter, section, or paragraph, the focus is on one sentence: Aristotle’s _Nicomachean Ethics_ III.5 1113b7-8. This sentence has markedly shaped scholarly and general opinion alike with regard to Aristotle’s theory of free will. In addition, it has taken on a curious life of its own. Part one of the chapter examines the text itself. Part two explores its reception from antiquity to the present day, including present-day popular culture, later ancient, Byzantine, Arabic, Latin Medieval, Renaissance, Victorian, and contemporary scholarship. There are some surprises on the way.

This chapter shows that contrary to the prevalent view, in his _De Interpretatione_ 8, Aristotle is concerned with homonymy; more precisely, with homonymy of linguistic expressions as it may occur in dialectical argument. The first part argues that in _Soph. el._ 175 b 39-176 a 5, Aristotle indubitably deals with homonymy in dialectical argument; that _De Interpretatione_ 8 is a parallel to _Soph. el._ 175 b 39-176 a 5; that _De Interpretatione_ 8 is concerned with dialectical argument; and that _De Interpretatione_ 8, too, deals with homonymy in dialectical argument. The second part of the chapter discusses objections that have been put forward against the view that _De Interpretatione_ 8 is about homonymy and shows that they do not succeed.

This volume assembles nine of the author’s essays on determinism, freedom, and moral responsibility in Western antiquity, ranging from Aristotle via the Epicureans and Stoics to the third century. It is representative of the author’s overall scholarship on the topic, much of which emphasizes that what commonly counts as ‘the problem of free will and determinism’ is noticeably distinct from the issues the ancients discussed. It is true that one main component of the ancient discourse concerned the question how moral accountability can be consistently combined with certain causal factors that impact human behaviour. However, it is not true that the ancient problems involved the questions of the compatibility of causal determinism with our ability to do otherwise or with free will. Instead, we encounter questions about human rational and autonomous agency and their compatibility with preceding causes, external or internal; with external impediments; with divine predetermination and theological questions; with physical theories like atomism and continuum theory, and with sciences more generally; with elements that determine character development from childhood, such as nature and nurture; with epistemic features such as ignorance of circumstances; with necessity and modal theories generally; with folk theories of fatalism; and also with questions of how human autonomous agency is related to moral development, to virtue and wisdom, to blame and praise. In Classical and Hellenistic philosophy, these questions were all debated without reference to freedom to do otherwise or free will—. This volume considers all of these questions to some extent.

Although Aristotle had no worked-out notion of a conditional, later Peripatetics did. Little has been said about Peripatetic conditionals so far. This paper examines the historical evidence and the philosophical and logical characteristics of these conditionals, thus providing some fresh insights. Specifically, it (i) explores the Peripatetic containment relations both between terms and between sentences; (ii) analyses how Peripatetic one-way and two-way conditionals relate to transitivity, symmetry and reflexivity; and (iii) reveals how Peripatetics deliberately anchored their concept of conditionals in passages from Aristotle’s Organon.

This paper reexamines Frege’s Lauben passage, a brief but influential segment in his 1918 essay Thought that has shaped contemporary theories of indexicals and elicited persistent interpretive challenges. Against the dominant tradition—which privileges Frege’s incommunicable I-thoughts and assumes their communicative intent—I argue that this approach misreads both the text and Frege’s philosophical priorities. Through close textual analysis, I identify mistranslations and structural misapprehensions that have skewed the passage’s reception. Building on these findings, I reconstruct a coherent account of Frege’s theory of indexical thought, clarifying the distinction between communicable and incommunicable I-thoughts and their respective roles in thinking and communication. This recalibration not only dissolves the need for alternative communication models but also invites a reclassification of essential indexicals and anaphoric indexicals within Frege’s framework. While no formalization is offered, the paper lays a more durable groundwork for the engagement with Frege’s late philosophy of language. Forthcoming in "The Oxford Studies in Philosophy of Language", Volume 4, 2025, Ernie Lepore & David Sosa (eds)

This paper offers a generic revenge-proof solution to the Sorites paradox that is compatible with several philosophical approaches to vagueness, including epistemicism, supervaluationism, psychological contextualism and intuitionism. The solution is traditional in that it rejects the Sorites conditional and proposes a modally expressed weakened conditional instead. The modalities are defined by the first-order logic QS4M+FIN. (This logic is a modal companion to the intermediate logic QH+KF, which places the solution between intuitionistic and classical logic.) Borderlineness is introduced modally as usual. The solution is innovative in that its modal system brings out the semi-determinability of vagueness. Whether something is borderline and whether a predicate is vague or precise is only semi-determinable: higher-order vagueness is columnar. Finally, the solution is based entirely on two assumptions. (1) It rejects the Sorites conditional. (2) It maintains that if one specifies borderlineness in terms of the ‒suitably interpreted‒ modal logic QS4M+FIN, then one can explain why the Sorites appears paradoxical. From (1)+(2) it results that one can tell neither where exactly in a Sorites series the borderline zone starts and ends nor what its extension is. Accordingly, the solution is also called agnostic.

This mainly historical paper provides a comprehensive discussion of the – heretofore neglected – evidence for Peripatetic syllogistic in Sextus Empiricus. The paper sets out to show that it is likely that in Sextus (and Apuleius) there is valuable evidence of a transitional period in later ancient logic that is marked out by a number of characteristics, which include the following: (i) A Peripatetic term ‘categorical syllogism’ is newly in use, but no term ‘hypothetical syllogism’ has been established yet. (ii) Stoic and Peripatetic logic are treated as complementing each other. (iii) The reversion of quantified propositions from predicate-subject to subject-predicate form is still fairly new. (iv) The so-called crocodile example is used to show that induction lacks the feature of concluding by necessity that is a defining mark of Aristotelian syllogisms. (v) The use of the expression katholikê protasis for categorical universal premise-propositions is distinctive of the period. (vi) The argument forms displayed by Sextus’ three examples appear to be indirectly related to the soon-to-appear Platonist hypothetical syllogistic. (vii) There are parallels that suggest that Sextus’ source belongs to the same historical period of logic as Apuleius’ source and as some probably recent source of Alexander of Aphrodisias’ Prior Analytics commentary (which is presented along with some later views and arguments, which may include Alexander’s own). Small differences between the three authors show that Sextus did not draw on the Greek handbook that was Apuleius’ source.

In their paper ‘Why Frege did not plagiarize the Stoics’ (Gabriel et al. 2024), G. Gabriel, K. Hülser and D. Rami provide an extended set of arguments to show that Frege didn’t, and couldn’t have, plagiarize(d) the Stoics via Prantl’s long chapter on Stoic logic (Prantl 1855) or at all, thus attempting to counter Bobzien’s 2021 ‘Frege plagiarized the Stoics’. The present short essay is Part II of a four-part refutation of Gabriel et al. 2024: The authors repeatedly ‒ and wrongly ‒ claim that there is a tradition of Stoic logic (and Stoic logical terminology) transmitted continuously from antiquity to the 19th century that was generally known in the 18th and 19th centuries. In this second part of the refutation, it is shown that, and why, the authors are entirely mistaken on every one of these points.

This paper is a discussion of Gabriel, Hülser and Schlotter’s 2009 article on a possible causal relation between Stoic logic and Frege. The paper provides detailed argument for why Rudolf Hirzel should not be taken as the qualified middleman in philosophical discussion with whom Frege learned what he ‘borrowed’ without acknowledgement from Stoic logic. Additionally, this paper offers some modest findings about some aspects of Frege's and Hirzel's lives and work habits, which may help us understand a little better Frege's connection to Hirzel and to Stoic logic as well as Frege’s failure to acknowledge the Stoics. This paper is a purely historical offshoot of my essay ‘Frege plagiarized the Stoics’. Zero direct insights into either Frege’s or Stoic philosophy are offered. OPEN ACCESS. Choose 'without proxy' below.

This paper offers a generic revenge-proof solution to the Sorites paradox that is compatible with several philosophical approaches to vagueness, including epistemicism, supervaluationism, psychological contextualism and intuitionism. The solution is traditional in that it rejects the Sorites conditional and proposes a modally expressed weakened conditional instead. The modalities are defined by the first-order logic QS4M+FIN. (This logic is a modal companion to the intermediate logic QH+KF, which places the solution between intuitionistic and classical logic.) Borderlineness is introduced modally as usual. The solution is innovative in that its modal system brings out the semi-determinability of vagueness. Whether something is borderline and whether a predicate is vague or precise is only semi-determinable: higher-order vagueness is columnar. Finally, the solution is based entirely on two assumptions. (1) It rejects the Sorites conditional. (2) It maintains that if one specifies borderlineness in terms of the ‒suitably interpreted‒ modal logic QS4M+FIN, then one can explain why the Sorites appears paradoxical. From (1)+(2) it results that one can tell neither where exactly in a Sorites series the borderline zone starts and ends nor what its extension is. Accordingly, the solution is also called agnostic.

ABSTRACT: In this paper I show that, contrary to the prevalent view, in his De Interpretatione chapter 8, Aristotle is concerned with a kind of ambiguity, i.e. with homonymy; more precisely, with homonymy of linguistic expressions as it may occur in dialectical argument. The paper has two parts. In the first part, I argue that in the Sophistici Elenchi 175b39-176a5 Aristotle indubitably deals with homonymy in dialectical argument; that De Interpretatione 8 is a parallel to Sophistici Elenchi 175b39-176a5; that De Interpretatione 8 is concerned with dialectical argument; that, hence, De Interpretatione 8, too, deals with homonymy in dialectical argument. In the second part I discuss objections that have been put forward against the view that De Interpretatione 8 is about homonymy and demonstrate that they do not succeed.

In this extended essay, I argue that Frege plagiarized the Stoics --and I mean exactly that-- on a large scale in his work on the philosophy of logic and language as written mainly between 1890 and his death in 1925 (much of which published posthumously) and possibly earlier. I use ‘plagiarize' (or 'plagiarise’) merely as a descriptive term. The essay is not concerned with finger pointing or casting moral judgement. The point is rather to demonstrate carefully by means of detailed evidence that there are numerous (over a hundred) and extensive parallels both in formulation and --more importantly-- in content between the Stoics and Frege, parallels so plentiful that one would be hard pressed to brush them off as coincidence. These parallels include several that appear to occur in no other modern works that were published before Frege’s own and were accessible to him. Additionally, a cluster of corroborating historical data is adduced to support the suggestion, showing how easy it would have to been for Frege to plagiarize the Stoics. This (first) part of the essay is easy to read and vaguely entertaining, or so I hope. (Corrigendum: At school, Frege likely had seven, not ten, years of intensive Latin and four years of intensive ancient Greek courses.)

We argue that the extant evidence for Stoic logic provides all the elements required for a variable-free theory of multiple generality, including a number of remarkably modern features that straddle logic and semantics, such as the understanding of one- and two-place predicates as functions, the canonical formulation of universals as quantified conditionals, a straightforward relation between elements of propositional and first-order logic, and the roles of anaphora and rigid order in the regimented sentences that express multiply general propositions. We consider and reinterpret some ancient texts that have been neglected in the context of Stoic universal and existential propositions and offer new explanations of some puzzling features in Stoic logic. Our results confirm that Stoic logic surpasses Aristotle’s with regard to multiple generality, and are a reminder that focusing on multiple generality through the lens of Frege-inspired variable-binding quantifier theory may hamper our understanding and appreciation of pre-Fregean theories of multiple generality.

This paper discusses ancient versions of paradoxes today classified as paradoxes of presupposition and how their ancient solutions compare with contemporary ones. Sections 1–4 air ancient evidence for the Fallacy of Complex Question and suggested solutions, introduce the Horn Paradox, consider its authorship and contemporary solutions. Section 5 reconstructs the Stoic solution, suggesting the Stoics produced a Russellian-type solution based on a hidden scope ambiguity of negation. The difference to Russell’s explanation of definite descriptions is that in the Horn Paradox the Stoics uncovered a hidden conjunction rather than existential sentence. Sections 6 and 7 investigate hidden ambiguities in “to have” and “to lose” and ambiguities of quantification based on substitution of indefinite plural expressions for indefinite or anaphoric pronouns, and Stoic awareness of these. Section 8 considers metaphorical readings and allusions that add further spice to the paradox.