Edward Zalta

The authors evaluate the soundness of the ontological argument they developed in their 1991 paper. They focus on Anselm’s first premise, which asserts that there is a conceivable thing than which nothing greater can be conceived. After casting doubt on the argument Anselm uses in support of this premise, the authors show that there is a formal reading on which it is true. Such a reading can be used in a sound reconstruction of the argument. After this reconstruction is developed in precise detail, the authors show that the conclusion, a reading of the claim “God exists”, does not quite achieve the end Anselm desired.

In this paper, the author analyzes critically some of the ideas found in Karel Lambert's recent book, Meinong and the Principle of Independence (Cambridge: Cambridge University Press, 1983). Lambert attempts to forge a link between the ideas of Meinong and the free logicians. The link comes in the form of a principle which, Lambert says, these philosophers adopt, namely, Mally's Principle of Independence, which Mally himself later abandoned. Instead of following Mally and attempting to formulate the principle in the material mode as the claim that an object can have properties without having any sort of being, Lambert formulates the principle in the formal mode, as (something equivalent to) the rejection of the traditional constraint on the principle of predication. The principle of predication is that a formula of the form Fa' is true iff the general term F' is true of the object denoted by the object term a'. The traditional constraint on this predication principle is that for the sentence Fa' to be true, not only must the object term have a denotation, but it must also denote an object that has being. According to Lambert, the free logicians violate this constraint by suggesting that Fa' can be true even if the object term has no denotation, whereas Meinong violates this constraint by proposing Fa' can be true even when the object term denotes an object that has no being. Lambert then tries to `vindicate' the Principle of Independence, thereby justifying both the work of the free logicians and Meinong.

Three different notions of concepts are outlined: one derives from Leibniz, while the other two derive from Frege. The Leibnizian notion is the subject of his "calculus of concepts" (which is really an algebra). One notion of concept from Frege is what we would call a "property", so that when Frege says "x falls under the concept F", we would say "x instantiates F" or "x exemplifies F". The other notion of concept from Frege is that of the notion of sense, which played various roles within Frege's theory. This notion of concept can be generalized and, as such, accounts for our intuitive talk of "x's concept of ...", where the ellipsis can be filled in with a name for individual, a property, or a relation, etc. After outlining these three notions, I then discuss how (axiomatic) object theory offers a distinct, precise regimentation of each of the three notions.

The principal goal of this entry is to present Frege's Theorem (i.e., the proof that the Dedekind-Peano axioms for number theory can be derived in second-order logic supplemented only by Hume's Principle) in the most logically perspicuous manner. We strive to present Frege's Theorem by representing the ideas and claims involved in the proof in clear and well-established modern logical notation. This prepares one to better prepared to understand Frege's own notation and derivations, and read Frege's original work (whether in German or in translation). Moreover, this should prepare the reader to understand a number of scholarly books and articles in the secondary literature on Frege's work.

In this paper I propose a fundamental modification of standard type theory, produce a new kind of type theoretic language, and couch in this language a comprehensive theory of abstract individuals and abstract properties and relations of every type. I then suggest how to employ the theory to solve the four following philosophical problems: the identification and ontological status of Frege's Senses; the deviant behavior of terms in propositional attitude contexts; the non-identity of necessarily equivalent propositions, and the paradox of analysis. We can roughly describe these solutions as follows: the senses of English names and descriptions which denote individuals will be modelled as abstract individuals; the senses of English relation denoting expressions of a given type will be modelled as abstract relations of that type. Inside de dicto attitude contexts, these English expressions denote their senses. Relations and propositions will not be identified with their extensions, nor with functions or sets of any kind. They will be taken as primitive, and precise being and identity conditions will be proposed consistent with the view that necessarily equivalent relations and propositions may be distinct. With the modelling described in, the expressions being a brother and being a male sibling may both denote the same property, though their senses may differ. Just as Frege predicts, being a brother just is being a male sibling is an informative identity statement because the terms flanking the identity sign have the same denotation, though distinct senses

Mathematical pluralism can take one of three forms: (1) every consistent mathematical theory consists of truths about its own domain of individuals and relations; (2) every mathematical theory, consistent or inconsistent, consists of truths about its own (possibly uninteresting) domain of individuals and relations; and (3) the principal philosophies of mathematics are each based upon an insight or truth about the nature of mathematics that can be validated. (1) includes the multiverse approach to set theory. (2) helps us to understand the significance of the distinguished non‐logical individual and relation terms of even inconsistent theories. (3) is a metaphilosophical form of mathematical pluralism and hasn't been discussed in the literature. In what follows, I show how the analysis of theoretical mathematics in object theory exhibits all three forms of mathematical pluralism.

In this paper, the author compares passages from two philosophically important texts and concludes that they have fundamental ideas in common. What makes this comparison and conclusion interesting is that the texts come from two different traditions in philosophy, the analytic and the phenomenological. In 1912, Ernst Mally published *Gegenstandstheoretische Grundlagen der Logik und Logistik*, an analytic work containing a combination of formal logic and metaphysics. In 1913, Edmund Husserl published *Ideen zu einer reinen Phänomenologie und phänomenologischen Philosophie*, a seminal work in phenomenology in which noemata are defined and given a crucial role in directing our mental states. In the passages from these two texts reproduced below, the author shows that the abstract `determinates' postulated by Mally in 1912 are assigned much the same role that Husserl assigned to noemata in 1913. Though Mally's determinates are not as highly structured as Husserl's noemata, they have a feature that explains how they manage to play the role assigned to them. The corresponding feature is missing, or at least, not emphasized in Husserl's account of noemata. Therefore, insights from both philosophers, and thus from both the analytic and phenomenological traditions, are needed to give a more complete account of directed mental states.

In this paper, the author responds to D. Jacquette's paper, "Mally's Heresy and the Logic of Meinong's Object Theory'' (History and Philosophy of Logic, 10, 1989, 1-14), in which it is claimed that Ernst Mally's distinction between two modes of predication, as it is employed in the theory of abstract objects, is reducible to, and analyzable in terms of, a single mode of predication plus the distinction between nuclear and extranuclear properties. The argument against Jacquette's claims consists of counterexamples to his reductions and analyses. Reasons are offered for thinking that no such reduction/analysis of the kind Jacquette proposes could be successful.

In this paper, the author replies to a question raised about theories of nonexistent objects. The question concerns the way names of fictional characters, when analyzed as names which denote nonexistent objects, acquire their denotations. Since nonexistent objects cannot causally interact with existent objects, it is thought that we cannot appeal to a‘dubbing’or a‘baptism’. The question is, therefore, what is the starting point of the chain? The answer is that storytellings are to be thought of as extended baptisms, and the details of this response receive attention in the paper. Once the storytelling is complete, and the characters have been baptized, a priori metaphysical principles linking the storytelling with the realm of nonexistent objects provide the referential, non‐causal connection between the names used in the storytelling and the objects denoted by such names.

Principia Logico-Metaphysica contains a foundational logical theory for metaphysics, mathematics, and the sciences. It includes a canonical development of Abstract Object Theory [AOT], a metaphysical theory that distinguishes between ordinary and abstract objects. This article reports on recent work in which AOT has been successfully represented and partly automated in the proof assistant system Isabelle/HOL. Initial experiments within this framework reveal a crucial but overlooked fact: a deeply-rooted and known paradox is reintroduced in AOT when the logic of complex terms is simply adjoined to AOT’s specially formulated comprehension principle for relations. This result constitutes a new and important paradox, given how much expressive and analytic power is contributed by having the two kinds of complex terms in the system. Its discovery is the highlight of our joint project and provides strong evidence for a new kind of scientific practice in philosophy, namely, computational metaphysics. Our results were made technically possible by a suitable adaptation of Benzmüller’s metalogical approach to universal reasoning by semantically embedding theories in classical higher-order logic. This approach enables one to reuse state-of-the-art higher-order proof assistants, such as Isabelle/HOL, for mechanizing and experimentally exploring challenging logics and theories such as AOT. Our results also provide a fresh perspective on the question of whether relational type theory or functional type theory better serves as a foundation for logic and metaphysics.

Formulations of Anselm’s ontological argument have been the subject of a number of recent studies. We examine these studies in light of Anselm’s text and (a) respond to criticisms that have surfaced in reaction to our earlier representations of the argument, (b) identify and defend a more refined representation of Anselm’s argument on the basis of new research, and (c) compare our representation of the argument, which analyzes that than which none greater can be conceived as a definite description, to a representation that analyzes it as an arbitrary name.

In this book, Dennett determines just how far we can push the idea that mental states are distinguished by intentionality, that is, by the fact that they have content in virtue of being about, or directed towards, the world at large. Intentionality is characteristic of such states as belief and desire, since all belief is belief of something or that something be the case. In contrast to the physical stance and the design stance, the intentional stance is the predictive attitude or strategy philosophers or cognitive scientists adopt when, in order to explain the behavior of a sufficiently complex system, they treat it as if it had beliefs and desires and acted rationally on its beliefs to satisfy its desires. Dennett insists that this stance is essentially a heuristic that informs the formation of scientific theories which are void of mental state terms. For Dennett, the interesting question, whether we are considering mechanical systems, computer systems, enzymes, microorganisms, vervet monkeys, humans, or martians, is just how far should we go in employing the intentional strategy? At what point must we abandon a strict realism about beliefs, desires, and the other concepts of folk psychology?

The authors evaluate the soundness of the ontological argument they developed in their 1991 paper. They focus on Anselm’s first premise, which asserts that there is a conceivable thing than which nothing greater can be conceived. After casting doubt on the argument Anselm uses in support of this premise, the authors show that there is a formal reading on which it is true. Such a reading can be used in a sound reconstruction of the argument. After this reconstruction is developed in precise detail, the authors show that the conclusion, a reading of the claim “God exists”, does not quite achieve the end Anselm desired.

An axiomatic theory of abstract objects is developed and used to construct models of Plato's Forms, Leibniz's Monads, Possible Worlds, Frege's Senses, stories, and fictional characters. The theory takes six primitive metaphysical notions: object ; n-place relations ,G,...); x,...x exemplify F x...x); x exists ; it is necessary that "); and x encodes F "). Properties and propositions are one place and zero place relations, respectively.objects are objects which necessarily fail to exist E!x"). The two most important proper axioms are that no possibly existing object encodes any properties E!x F)xF)), and for every expressible condition on properties, there is an abstract object which encodes just the properties satisfying the condition x) )), where has no free x's). Semantically, an abstract object encodes a property iff the property is an element of the set of properties correlated with the object. Two abstract objects will be identical just in case they encode the same properties. Abstract objects may exemplify properties as well--being non-red, not having spatial location, etc. ;The models of Forms, Monads, and Possible Worlds consist in: identifying these philosophical entities as different species of abstract objects through definitions of the object language, and either showing that there are consequences of the theory which are reasonable facsimiles of assertions made by important philosophers or showing that there are many interesting theorems which capture our own intuitions about these entities . The model for Frege's Senses consists in: developing a language in which the abstract objects generated by the theory serve as the senses of names and descriptions, and showing that the data may be consistently translated into the language preserving truth. Finally, the model for fictional characters consists in: assigning abstract objects to serve as the denotations of names of stories and characters, and showing that such an assignment allows us to understand how the intuitively true sentences about stories and characters have the truth value that they do. ;The material is structured as follows. In Chapters I, III, and V, the elementary, modal, and typed theories of abstract objects are developed, respectively. In Chapters II, IV, and VI, these theories are applied, respectively. Each of the theoretical chapters is subdivided as follows: 1--The Language; 2--The Semantics; 3--The Logic; and 4--The Proper Axioms. Thus, the proper axioms of the theory are couched in a precisely defined and interpreted language, and the logic allow us to prove the consequences of the theory

In a recent book, K. Lambert argues that philosophers should adopt Mally's Principle of Independence (the principle that an object can have properties even though it lacks being of any kind) by abandoning a constraint on true predications, namely, that all of the singular terms in a true predication denote objects which have being. The constraint may be abandoned either by supposing there is a true predication in which one of the terms denotes a beingless object (Meinong) or by supposing there is a true predication in which one of the terms denotes nothing at all (free logic). However, Lambert's conclusions can be undermined by showing that the data he produces in support of his position can be explained by either of two recent theories of abstract and nonexistent objects, both of which are couched in languages which conform to the traditional constraint.

The formulation of propositional modal logic is revised by interposing a domain of structured propositions between the modal language and the models. Interpretations of the language (i.e., ways of mapping the language into the domain of propositions) are distinguished from models of the domain of propositions (i.e., ways of assigning truth values to propositions at each world), and this contrasts with the traditional formulation. Truth and logical consequence are defined, in the first instance, as properties of, and relations among, propositions. These definitions have certain interesting consequences. One is that they resolve a question that cannot be answered by the traditional analysis, in which Kripke models directly interpret modal language. The question is, is the reason a modal sentence has a different truth value at other possible worlds due to the fact that the sentence has a different meaning at that world or due to a change in the world? The philosophical conception elaborates the second answer. Another interesting consequence is that modal language, properly speaking, is not intensional, at least according to the classic tests for, and definitions of, intensionality.

In a recent book, K. Lambert argues that philosophers should adopt Mally's Principle of Independence (the principle that an object can have properties even though it lacks being of any kind) by abandoning a constraint on true predications, namely, that all of the singular terms in a true predication denote objects which have being. The constraint may be abandoned either by supposing there is a true predication in which one of the terms denotes a beingless object (Meinong) or by supposing there is a true predication in which one of the terms denotes nothing at all (free logic). However, Lambert's conclusions can be undermined by showing that the data he produces in support of his position can be explained by either of two recent theories of abstract and nonexistent objects, both of which are couched in languages which conform to the traditional constraint.