Hanoch Ben-Yami

I explain why model theory is unsatisfactory as a semantic theory and has drawbacks as a tool for proofs on logic systems. I then motivate and develop an alternative, the truth-valuational substitutional approach (TVS), and prove with it the soundness and completeness of the first order Predicate Calculus with identity and of Modal Propositional Calculus. Modal logic is developed without recourse to possible worlds. Along the way I answer a variety of difficulties that have been raised against TVS and show that, as applied to several central questions, model-theoretic semantics can be considered TVS in disguise. The conclusion is that the truth-valuational substitutional approach is an adequate tool for many of our logic inquiries, conceptually preferable over model-theoretic semantics. Another conclusion is that formal logic is independent of semantics, apart from its use of the notion of truth, but that even with respect to it its assumptions are minimal.

Descartes was the first to hold that, when we perceive, the representation need not resemble what it represents but should correspond to it. Descartes developed this ground-breaking, influential conception in his work on analytic geometry and then transferred it to his theory of perception. I trace the development of the idea in Descartes’ early mathematical works; his articulation of it in Rules for the Direction of the Mind; his first suggestions there to apply this kind of representation-by-correspondence in the scientific inquiry of colours; and, finally, the transfer of the idea to the theory of perception in The World.

The Quantified Argument Calculus (Quarc) is a formal logic system, first developed by Hanoch Ben-Yami in (Ben-Yami 2014), and since then extended and applied by several authors. The aim of this paper is to further these contributions by, first, providing a philosophical motivation for the truth-valuational, substitutional approach of (Ben-Yami 2014) and defending it against a common objection, a topic also of interest beyond its specific application to Quarc. Second, we fill the formal lacunae left in the original presentation, which did not incorporate identity systematically into Quarc, and although it proved the soundness of the system did not prove its completeness.

I try to identify elements of our mental capacities that separate us from animals. I focus on our command of logical concepts, demonstrable already in children in the second or third year of their life, which to date no animal has been shown to master. I draw various conclusions about the behavioural, intellectual, emotional, and moral capacities that depend on this mastery, and discuss recent empirical research that either supports or apparently disagrees with the claim that animals, even those we consider intelligent, are limited in these respects. My discussion is built around observations extracted from Wittgenstein.

We introduce a two-valued and a three-valued truth-valuational substitutional semantics for the Quantified Argument Calculus (Quarc). We then prove that the 2-valid arguments are identical to the 3-valid ones with strict-to-tolerant validity. Next, we introduce a Lemmon-style Natural Deduction system and prove the completeness of Quarc on both two- and three-valued versions, adapting Lindenbaum’s Lemma to truth-valuational semantics. We proceed to investigate the relations of three-valued Quarc and the Predicate Calculus (PC). Adding a logical predicate T to Quarc, true of all singular arguments, allows us to represent PC quantification in Quarc and translate PC into Quarc, preserving validity. Introducing a weak existential quantifier into PC allows us to translate Quarc into PC, also preserving validity. However, unlike the translated systems, neither extended system can have a sound and complete proof system with Cut, supporting the claim that these are basically different calculi.

Fictional characters do not really exist. Names of fictional characters refer, to fictional characters. We should divorce the idea of reference from that of existence (the picture of the name as a tag has limited applications; the Predicate Calculus, with its existential quantifier, does not adequately reflect the relevant concepts in natural language; and model theory, with its domains, might also have been misleading). Many puzzle-cases are resolved this way (among other things, there is no problem assigning negative existential statements the appropriate truth values). And fictional characters, although not existing, have real powers through their representations, which are real.

In the first chapter of his The World, Descartes compares light to words and discusses signs and ideas. This made scholars read into that passage our views of language as a representational medium and consider it Descartes’ model for representation in perception. I show, by contrast, that Descartes does not ascribe there any representational role to language; that to be a sign is for him to have a kind of causal role; and that he is concerned there only with the cause’s lack of resemblance to its effect, not with the representation’s lack of resemblance to what it represents. I support this interpretation by comparisons with other places in Descartes’ corpus and with earlier authors, Descartes’ likely sources. This interpretation may shed light both on Descartes’ understanding of the functioning of language and on the development of his theory of representation in perception.

The formalisation of Natural Language arguments in a formal language close to it in syntax has been a central aim of Moss’s Natural Logic. I examine how the Quantified Argument Calculus (Quarc) can handle the inferences Moss has considered. I show that they can be incorporated in existing versions of Quarc or in straightforward extensions of it, all within sound and complete systems. Moreover, Quarc is closer in some respects to Natural Language than are Moss’s systems – for instance, is does not use negative nouns. The process also sheds light on formal properties and presuppositions of some inferences it formalises. Directions for future work are outlined.

The Modal Predicate Calculus gives rise to issues surrounding the Barcan formulas, their converses, and necessary existence. I examine these issues by means of the Quantified Argument Calculus, a recently developed, powerful formal logic system. Quarc is closer in syntax and logical properties to Natural Language than is the Predicate Calculus, a fact that lends additional interest to this examination, as Quarc might offer a better representation of our modal concepts. The validity of the Barcan formulas and their converses is shown by Quarc to be a result of the specific incorporation of quantification in the Predicate Calculus, and not as reflecting a feature of the interaction of quantification and modality more generally. Necessary existence is shown to follow from the identification, in the Predicate Calculus on its canonical interpretation, of particular quantification, ascription of existence and the ‘there is’ construction, three constructions which are distinguished in both Quarc and Natural Language. The issues surrounding the Barcan formulas, their converses and necessary existence are thus shown to be an artefact of a specific logic system, not an essential feature of our relevant modal concepts or of formal logic.

I explain in what sense the structure of space and time is probably vague or indefinite, a notion I define. This leads to the mathematical representation of location in space and time by a vague interval. From this, a principle of complementary inaccuracy between spatial location and velocity is derived, and its relation to the Uncertainty Principle discussed. In addition, even if the laws of nature are deterministic, the behaviour of systems will be random to some degree. These and other considerations draw classical physics closer to Quantum Mechanics. An arrow of entropy is also derived, given an arrow of time. Lastly, chaos is given an additional, objective meaning.

There is currently a theoretical tension between young children’s failure in False Belief Tasks (FBTs) and their success in a variety of other tasks that also seem to require the ability to ascribe false beliefs to agents. We try to explain this tension by the hypothesis that in the FBT, children think they are asked what the agent should do in the circumstances and not what the agent will do. We explain why this hypothesis is plausible. We examined the hypothesis in two experiments, each involving a new task. In the first task, the hypothesised misunderstanding of the question leads to failure without the need to ascribe a false belief, and we show that failure in this new task is correlated with failure in the FBT. In the second task, passing which requires ascribing a false belief to an agent, and for which we have partial yet encouraging results, the children are asked a question which is unlikely to be misunderstood. Children pass this task much more often than they do a standard FBT. The mentioned tension is thus resolved. We conclude that the so-called False Belief Task probably does not check the ability to ascribe false beliefs but rather linguistic development.

Ben-Yami presents Wittgenstein’s explicit criticism of the Platonic identification of an explanation with a definition and the alternative forms of explanation he employed. He then discusses a few predecessors of Wittgenstein’s criticisms and the Fregean background against which he wrote. Next, the idea of family resemblance is introduced, and objections answered. Wittgenstein’s endorsement of vagueness and the indeterminacy of sense are presented, as well as the open texture of concepts. Common misunderstandings are addressed along the way. Wittgenstein’s ideas, as is then shown, have far-reaching implications for knowledge of meaning and the nature of logic, and with them to the nature of the philosophical project and its possible achievements.

I first show that most authors who developed Plural Quantification Logic (PQL) argued it could capture various features of natural language better than can other logic systems. I then show that it fails to do so: it radically departs from natural language in two of its essential features; namely, in distinguishing plural from singular quantification and in its use of an relation. Next, I sketch a different approach that is more adequate than PQL for capturing plural aspects of natural language semantics and logic. I conclude with a criticism of the claim that PQL should replace natural language for specific philosophical or scientific purposes

I reconstruct from Rietdijk and Putnam’s well-known papers an argument against the applicability of the concept of becoming in Special Relativity, which I think is unaffected by some of the objections found in the literature. I then consider a line of thought found in the discussion of the possible conventionality of simultaneity in Special Relativity, beginning with Reichenbach, and apply it to the debate over becoming. We see that it immediately renders Rietdijk and Putnam’s argument unsound. I end by comparing my approach to others found in the literature, primarily Stein’s

  Searle's Chinese Room was supposed to prove that computers can't understand: the man in the room, following, like a computer, syntactical rules alone, though indistinguishable from a genuine Chinese speaker, doesn't understand a word. But such a room is impossible: the man won't be able to respond correctly to questions like What is the time?, even though such an ability is indispensable for a genuine Chinese speaker. Several ways to provide the room with the required ability are considered, and it is concluded that for each of these the room will have understanding. Hence, Searle's argument is invalid

In recent literature on plurals the claim has often been made that the move from singular to plural expressions can be iterated, generating what are occasionally called higher-level plurals or superplurals, often correlated with superplural predicates. I argue that the idea that the singular-to-plural move can be iterated is questionable. I then show that the examples and arguments intended to establish that some expressions of natural language are in some sense higher-level plurals fail. Next, I argue that these and some other expressions should instead be classified as plurals whose reference is articulated, an idea explained and elaborated in the paper. I also show that the related categories of plural and superplural predicates collapse to that of ordinary predicates. In the process we also see that the law of substitutivity salva veritate should be elaborated for cases involving expressions more complex than singular ones

The reason for characterizing mental states as propositional attitudes is sentence form: ‘S Vs that p’. However, many mental states are not ascribed by means of such sentences, and the sentences that ascribe them cannot be appropriately paraphrased. Moreover, even if a paraphrase were always available, that in itself would not establish the characterization. And the mental states that are ascribable by appropriate senses do not form any natural subset of mental states. A reason for the characterization relying on beliefs, etc., about non‐existing things is also rejected. Last, some sentences ascribing abilities and dispositions have the same grammatical form as some senses that ascribe mental states, so that the attempt to paraphrase the latter would obscure the conceptual relations between the two sorts. It follows that mental states are not relations to propositions

Dummett and others have failed to show that an effect can precede its cause. Dummett claimed that 'backwards causation' is unproblematic in agentless worlds, and tried to show under what conditions it is rational to believe that even backwards agent-causation occurs. Relying on considerations originating in discussions of special relativity, I show that the latter conditions actually support the view that backwards agent-causation is impossible. I next show that in Dummett's agentless worlds explanation does not necessitate backwards causation. I then show why even relative backwards causation is impossible in his and Tooley's scenarios of parallel processes in which causes apparently act in opposite temporal directions. We thus have good reasons for thinking that backwards causation is impossible

I develop Special Relativity with backward-light-cone simultaneity, which I call, for reasons made clear in the paper, ‘Apparent Simultaneity’. In the first section I show some advantages of this approach. I then develop the kinematics in the second section. In the third section I apply the approach to the Twins Paradox: I show how it removes the paradox, and I explain why the paradox was a result of an artificial symmetry introduced to the description of the process by Einstein’s simultaneity definition. In the fourth section I discuss some aspects of dynamics. I conclude, in a fifth section, with a discussion of the nature of light, according to which transmission of light energy is a form of action at a distance. deposited in Pittsburgh PhilSci-Archive, March 2007.

In Naming and Necessity Kripke argues 'intuitively' that names are rigid. Unlike Kripke, Ben-Yami first introduces and justifies the Principle of the Independence of Reference (PIR), according to which the reference of a name is independent of what is said in the rest of the sentence containing it. Ben-Yami then derives rigidity, or something close to it, from the PIR. Additional aspects of the use of names and other expressions in modal contexts, explained by the PIR but not by the rigidity claim, are then discussed. Ben-Yami next examines a difficulty in accepted definitions of rigidity, stemming from the fact that the same name can be used to name different particulars. This difficulty might force us to adopt a revised form of the rigidity claim.

I explain why I think that considerations regarding the opposing rights involved in the practice of circumcision—rights of the individual to bodily integrity and rights of the community to practice its religion—would not help us decide on the desirable policy towards this controversial practice. I then suggest a few measures that are not in conflict with either religious or community rights but that can both reduce the harm that circumcision as currently practiced involves and bring about a change in attitude towards the practice, thus further reducing its frequency. These measures are the compulsory administration of anaesthetics; the banning of the metzitzah b’peh; and having an upper age limit of a few months on nontherapeutic circumcision of minors. I conclude with general considerations on why the steps taken towards the reform of circumcision should be moderate.